stopover site ecology of montagu´s harrier (circus pygargus) in
TRANSCRIPT
That strange and mysterious phenomenon in the life of birds, their migratory journeys, repeated at fixed
intervals, and with unerring exactness, has for thousands of years
called forth the astonishment and admiration of mankind.
(H. Gätke 1895.)
Stopover site ecology
of Montagu´s Harrier (Circus pygargus)
in East-Morocco
Almut Schlaich
@ Rob Buiter
Carl von Ossietzky Universität Oldenburg Master of Science in Biology
MASTER´S THESIS
Stopover site ecology of Montagu´s Harrier ( Circus pygargus) in
East-Morocco Submitted by: Almut E. Schlaich Conducted at: Institute of Avian Research „Vogelwarte Helgoland“, Wilhelmshaven
and Dutch Montagu´s Harrier Foundation, The Netherlands 1st Examiner: Dr. Klaus-Michael Exo 2nd Examiner: Prof. Dr. Franz Bairlein Supervisors: Dr. Christiane Trierweiler, Ben J. Koks Oldenburg, 28 March 2011
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Table of Contents
1. Introduction ............................................................................................................... 3
1.1 Bird migration ....................................................................................................... 3
1.2 Stopovers during bird migrations .......................................................................... 4
1.3 Study species: Montagu´s Harrier (Circus pygargus) ........................................... 6
1.4 Study area: stopover site East-Morocco ............................................................. 11
1.5 Research goals .................................................................................................. 12
2. Materials and Methods ............................................................................................ 13
2.1 Satellite telemetry data ...................................................................................... 13
2.2 Location of the study area East-Morocco ........................................................... 14
2.3 Habitat characteristics of the study area East-Morocco ...................................... 15
2.4 Loose observations and localization of roosts .................................................... 17
2.5 Road transect counts ......................................................................................... 17
2.6 Habitat selection ................................................................................................ 18
2.7 Prey transect counts .......................................................................................... 19
2.8 Pellet analysis .................................................................................................... 23
2.9 Spatial and statistical analyses .......................................................................... 25
3. Results .................................................................................................................... 26
3.1 Montagu´s Harriers´ stopover sites in East-Morocco and their use as revealed
by satellite telemetry ................................................................................................ 26
3.2 Distribution and abundance of Montagu´s Harriers in East-Morocco: field data .. 35
3.3 Habitat selection during stopover ....................................................................... 40
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3.4 Prey abundance and prey choice ....................................................................... 47
4. Discussion ............................................................................................................... 57
5. Summary ................................................................................................................. 64
6. Zusammenfassung .................................................................................................. 66
7. Samenvatting .......................................................................................................... 68
8. Acknowledgements ................................................................................................. 71
9. Literature ................................................................................................................. 72
10. Appendix ............................................................................................................... 77
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1. Introduction
1.1 Bird migration
An estimated 50 billion birds worldwide migrate twice a year between their breeding
and non-breeding grounds (Berthold 1993). The phenomenon of seasonal use of
different areas, often on two continents, is the result of changing food availability at
higher latitudes. Whereas food is abundant on the breeding grounds in summer,
seasonal environments suffer from scarcity in winter. By migrating to areas closer to
the equator, often on the other hemisphere, birds avoid periods with low food
supplies in their breeding range. In the Palaearctic-Afrotropical migration system,
millions of birds are travelling every year between their breeding grounds in Europe
and the wintering areas in Africa, often south of the Sahara (Newton 2008; Zwarts et
al. 2009).
Migration to and from places visited in subsequent years by the same
individual bird requires great navigational skills. Birds covering thousands of
kilometers on their migratory routes use compass information as well as landscape
characteristics and other environmental cues for orientation (Alerstam 1990; Able
2001). Migration patterns are partly under genetic control, allowing juveniles to
perform the journey on their own, controlling the timing of migration and leading the
birds on the right routes (Helbig 1996). Nevertheless, migration systems can be
modified even within relatively short time intervals, as shown e.g. by migration
patterns in Blackcaps (Sylvia atricapilla) changing within 30 years to wintering in
Britain instead of the Mediterranean (Berthold & Querner 1995).
There are different strategies in birds to cover large distances. Birds can
either migrate as fast as possible to minimize the time spent on migration (‘time
minimization model’), which requires large fuel stores, or save energy due to lower
fat load if they have the possibility to stop and feed at multiple places on the route
(‘energy minimization model’; Alerstam & Lindström 1990). Observed strategies are
mostly a mixture of these models, depending on the species considered, on
conditions that vary e.g. between years, or on individual performance.
Migration is one of the most important stages of the yearly life cycle of
migratory birds, involving many hazards. Beside the direct costs of migratory flight,
journeying through various, often unknown landscapes can lead to additional costs.
Weather conditions, confrontation with diseases, competition and predation pressure
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en route and at wintering sites can have effects on individuals and their survival and
eventually on population dynamics.
Most raptor species are soaring birds, making use of thermals to gain height
and of gliding flight to cover inter-thermal distances (Alerstam 1990; Newton 2008).
Since the effectiveness of soaring flight is related to wing surface, species with
narrower and tipped wings use more flapping flight than species with broader wings.
Soaring flight requires the least energy of all forms of flight, hence some migratory
raptor species accept much longer routes than the direct connection between
breeding and wintering areas, avoiding barriers like open water (Newton 2008).
1.2 Stopovers during bird migrations
Regardless of the migration strategy followed by a species or an individual, often the
whole distance cannot be covered in a single flight. Birds may have to stop during
migration to refuel their energy stores. This is especially the case before and after
crossing large ecological barriers like deserts and oceans.
A recent review on the terminology of stopover vs. staging (Warnock 2010)
concluded that the term stopover relates to sites used for several days and by few
individuals of a population at any one time, whereas staging sites are used by
thousands of individuals for a longer period (for details see Table 1 in Warnock
2010). In this thesis, I investigate the stopover site ecology of the study species,
Montagu´s Harrier (Circus pygargus), in an area in East-Morocco that is used during
several days and not in high numbers at the same time (see results). Therefore, the
term stopover is used throughout the text.
Conditions at stopover sites can have an impact on migration speeds,
reproduction and survival rates of individual migrants through food availability,
competition, predation and disturbance, sometimes also affecting population size
(Newton 2008). Timing and success of migration may be strongly influenced by food
supply at stopover sites, where birds have to refuel in limited time (Newton 2008).
Food availability at stopover sites can influence the condition of individuals, which in
turn determines the frequency and duration of stopovers, and finally migration speed.
Interference and depletion competition might limit weight gain rates of birds at
stopover sites. Competitive interactions with conspecifics and inter-specific
competition can lead to differences in refueling rates, stopover duration and survival,
5
especially in species holding short-time territories (Newton 2008). Nevertheless, the
quality of a stopover site is not only influenced by food availability and competition,
but also by predation risk and other hazards (Newton 2008). For instance,
disturbances and parasites may influence the migratory performance of individual
birds by weakening the organism and lowering food intake rates (Newton 2008). Also
other factors like illegal persecution may play a role. All the factors mentioned above
can have impacts on the survival of an individual and on performance and success
during following breeding seasons, so called carry-over effects.
Kerlinger (2009) stated that “long-term survival of many species is linked to success
during migration, and thus to the preservation of stopover sites”. One factor that
potentially limits populations of migrants is the availability of stopover sites (Newton
2008). This holds especially true for waders, which have to stop over at adequate
coastal sites that are often far from each other. In contrast, land bird species may
have the possibility to stop over at various sites on their route, which also reduces
competition. Conditions at stopover sites and during migration may also have effects
on the population level due to additional mortality, as well as on the individual
through carry-over effects (Newton 2008; Bauchinger et al. 2009). This was shown
for White Storks (Ciconia ciconia) and Barn Swallows (Hirundo rustica), where
population changes correlated with conditions during stopover (Robinson et al. 2003;
Schaub et al. 2005). It was shown for several bird species that body condition at
migration sites corresponds to re-sighting rates and thus survival (Newton 2008,
Table 27.1), indicating the importance of favorable ecological conditions at stopover
sites.
Although a lot of information is available on migrations and stopovers in birds, most
studies refer to songbird species. Raptors differ in their migration ecology in many
points, because they are mostly heavier, often use soaring flight and, as predators,
depend on adequate prey. However, they face similar challenges and limitations at
stopover sites as other taxonomic groups of birds.
For many raptor species not much is known about the precise routes they
travel or the sites they use for stopover. At some migration bottlenecks, e.g.
Gibraltar, where amazing numbers of raptors pass by at the same time, regular
migration counts are carried out (Bensusan et al. 2007). In more remote places
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however, little is known about the whereabouts of these birds. Recently, new insights
were gained by satellite tracking of larger raptor species. This revealed for example
that most of the satellite-tagged Swedish Ospreys (Pandion haliaetus) made one
longer stopover of 3-4 weeks on autumn migration (Hake et al. 2001). Ospreys spent
more time on migration in autumn than in spring due to more stopover days
(Alerstam et al. 2006). Nevertheless, Ospreys seemed to minimize time spent on
autumn migration to arrive early at wintering sites for gaining a good territory (Kjellen
et al. 1997). This is possible because Ospreys are fly-and-forage migrants
(Strandberg & Alerstam 2007), which have the possibility to feed on the go.
However, the specialization in feeding only on fish limits appropriate stopover sites.
Ospreys therefore often continue migration when flying above non-optimal habitats,
because stopping over in e.g. arid areas brings no benefits (Thorup et al. 2006).
Another species employing the fly-and-forage strategy is the Marsh Harrier
(Circus aeruginosus; Klaassen et al. 2010). In a study on 17 satellite-tagged
Swedish Marsh Harriers, low migration speeds indicated stopover behavior on
autumn migration throughout Europe, but only one individual made a stopover in N-
Africa (Klaassen et al. 2010). During spring migration, however, the Marsh Harriers
made some stopovers at the northwestern coast of Africa and in Europe (Klaassen
et al. 2010).
A third example of raptor stopover behavior is shown by Bald Eagles
(Haliaeetus leucocephalus). These North American eagles are partial migrants, with
birds from populations breeding in Saskatchewan, Alberta, and the Northwest
Territories of Canada using traditional stopover sites on their migration southward
along the Rocky Mountains, where they feed on carcasses of salmon for several
weeks (Bildstein 2006).
1.3 Study species: Montagu´s Harrier ( Circus pygargus)
Of 193 bird species migrating from the West Palaearctic to sub-Saharan Africa, 24
are raptors (Newton 2008). Harriers (Circus) are raptors showing some distinct life
history traits and characteristic behaviors (Simmons 2000). All species share
morphological characteristics such as slender wings and long tails resulting in their
buoyant flight and exceptionally low wing loading (Simmons 2000). Some species of
the genus Circus are regularly polygynous, and it is possibly for this reason that
sexes are markedly dimorphic in plumage. The fact that all species are ground
breeders contributes to the separation of the genus from other raptors, as well as
their enormous acoustical abilities.
pass’ in the air between pairs of harriers.
Hen Harrier (Circus cyaneus
(C. macrourus; Simmons 2000).
or residential, the harrier species are
Montagu´s Harriers are sexually dimorphic (Fig. 1.1) with females weighing
about 345 g and males about 265 g (Table 2.2 in
distribution, their breeding range is centered in Europe, extending northward towards
Scandinavia and south to the Mediterranean and the coast of northwest Africa
(Clarke 1996). The breeding range also covers parts of Asi
Kazakhstan and the upper Yenisey
Fig. 1.1: Montagu´s Harrier (
Dutch Montagu´s Harrier Foundation.
Montagu´s Harriers are not endangered gl
countries as decreasing or endangered
sexes are markedly dimorphic in plumage. The fact that all species are ground
breeders contributes to the separation of the genus from other raptors, as well as
their enormous acoustical abilities. A special and spectacular behavior is the ‘food
pass’ in the air between pairs of harriers. Four species of harriers breed
Circus cyaneus), Marsh Harrier, Montagu´s Harrier, and Pallid Harrier
; Simmons 2000). Except for Hen Harriers, which are partial migrants
or residential, the harrier species are migrants wintering south of the Sahara.
Montagu´s Harriers are sexually dimorphic (Fig. 1.1) with females weighing
about 345 g and males about 265 g (Table 2.2 in Simmons 2000). With a Palaearctic
distribution, their breeding range is centered in Europe, extending northward towards
Scandinavia and south to the Mediterranean and the coast of northwest Africa
The breeding range also covers parts of Asia, extending eastwards to
Kazakhstan and the upper Yenisey (Del Hoyo et al. 1992).
Fig. 1.1: Montagu´s Harrier (Circus pygargus). A, C: Adult male, B, D: Adult female. Photos:
Dutch Montagu´s Harrier Foundation.
Montagu´s Harriers are not endangered globally but red-listed in some European
countries as decreasing or endangered (Burfield & Van Bommel 2004; Sudfeldt
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sexes are markedly dimorphic in plumage. The fact that all species are ground-
breeders contributes to the separation of the genus from other raptors, as well as
A special and spectacular behavior is the ‘food-
cies of harriers breed in Europe:
), Marsh Harrier, Montagu´s Harrier, and Pallid Harrier
Except for Hen Harriers, which are partial migrants
migrants wintering south of the Sahara.
Montagu´s Harriers are sexually dimorphic (Fig. 1.1) with females weighing
Simmons 2000). With a Palaearctic
distribution, their breeding range is centered in Europe, extending northward towards
Scandinavia and south to the Mediterranean and the coast of northwest Africa
a, extending eastwards to
). A, C: Adult male, B, D: Adult female. Photos:
listed in some European
(Burfield & Van Bommel 2004; Sudfeldt et al.
8
2008; Trierweiler & Koks 2009). Over half of the world population of Montagu´s
Harriers breeds in Europe (Arroyo et al. 2004; Burfield & Van Bommel 2004), but
substantial population declines have been observed in many well monitored
breeding areas (Zijlstra & Hustings 1992; Millon et al. 2004; Illner 2007; Trierweiler &
Koks 2009). With about 400 breeding pairs, Germany has the biggest Montagu´s
Harrier breeding population in NW-Europe (Mebs & Schmidt 2006).
Natural breeding habitats as moor and heath lands decreased in availability
for breeding. Therefore, at the end of the last century, Montagu´s Harriers started to
breed in agricultural land e.g. wheat, barley and alfalfa fields (Arroyo et al. 2004;
Koks et al. 2007). Habitat loss due to intensification of agricultural land use and
human persecution are the main causes of population declines of Montagu´s
Harriers since the 1940s (Clarke 1996). However, conditions in the wintering areas
may also have contributed to the observed population decrease (Thiollay 2006;
Zwarts et al. 2009).
Today, ground-breeding birds of agricultural landscapes face several threats
due to agricultural activities (Sudfeldt et al. 2008). Clutches, nestlings and incubating
females are in danger to be killed by mowing or harvesting. The population in The
Netherlands nearly went extinct in 1987. Therefore, conservation issues such as
nest protection and habitat improvements have been employed since the 1990s.
Thanks to a large scale set aside of farmland in 1988, the population started
increasing again (Koks et al. 2007). This positive trend continued due to intensive
conservation efforts of the Dutch Montagu´s Harrier Foundation and led to a
successful increase of the breeding pairs with about 50 pairs breeding in 2010
(Dutch Montagu´s Harrier Foundation, pers. comm.).
Montagu´s Harrier breeding biology
By the end of April, Montagu´s Harriers start arriving in their breeding areas in
northwestern Europe. In the first phase, pair formation takes place induced by
courtship behavior of males, e.g. courtship feedings and spectacular flight
maneuvers called ‘skydancing’. Pairs defend only small territories around their
nesting site during the breeding season. Nests are built on the ground by the female
and contain mostly 3-4 eggs. After 28-29 days of incubation by the female, the
nestlings hatch. During this time and when the chicks are young, the male provides
food for the female and the young. In the second half of the nestling phase, the
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female may start hunting again and may help feeding the nestlings. The nestling
period is normally 31-33 days, after fledging the young are still fed for several weeks.
Because females start incubating the clutch after laying the first egg, nestlings differ
in age and size (Clarke 1996). In autumn, females tend to leave the breeding area
about a week earlier than males and fledglings (Clarke 1996).
Montagu´s Harriers´ migrations
Because Montagu´s Harriers are long-distance migrants, they spend only four to five
months of the year in their breeding areas (see Fig. 1.2 in Trierweiler 2010). The
larger part of their life cycle is spent on migration and at wintering sites. Keeping in
mind that population dynamics are significantly influenced by ecological conditions
during migration and at wintering sites, including investigations of the whole life cycle
of a bird is of great importance (1) to deepen biological understanding and (2) to
maximize effects of conservation strategies (Bairlein 2003).
Ringing birds and analyzing ring recoveries is the oldest way of studying
migration and, along with providing large sample sizes, for many small species the
only possibility to gain insight in migration routes, stopover areas and wintering
grounds (Bairlein 2001). Up to 2008, only 47 ring recoveries of Montagu´s Harriers
were reported from Africa, thereof 15 south of the Sahara (see Fig. 180 in Trierweiler
& Koks 2009) illustrating roughly the wintering areas but not showing migration
routes.
Telemetry methods involving devices like radio tags, satellite transmitters or
GPS loggers deliver more extensive data than ringing, which do not depend on the
distribution of birdwatchers and different ring recovery probabilities. Furthermore,
these techniques deliver not one data point per bird like ringing, but up to several
thousand per individual. This also allows for studies on individual birds over years,
resulting in information on life cycle and lifetime reproductive success. Telemetry
also offers the opportunity to locate stopover sites precisely, whereas direct
observation methods can only use minimum values between first and last sighting
(Newton 2008). Nevertheless, the use of telemetry techniques is limited to species
large and heavy enough to carry the necessary transmitters or loggers.
Recently, the assumption of northwest European Montagu´s Harriers making
a loop migration via Gibraltar in autumn and returning via Italy in spring (García &
Arroyo 1998) was disproved by using telemetry data. In 2005, light enough satellite
10
transmitters were available to fit Montagu´s Harriers for the first time. Trierweiler et
al. (2007b) described for the first time the exact migration routes of Montagu´s
Harriers from the Netherlands to West Africa. They showed that about ¾ of the NW-
European population take a western route via France and Spain to winter in
Senegal, Mauretania and Mali and ¼ of the birds takes a central route via Italy to
Niger and Nigeria on spring as well as on autumn migration (Trierweiler 2010). The
satellite telemetry data revealed that for west European breeding birds the route via
Spain is of greatest overall importance (Trierweiler et al. 2007b; Exo et al. 2010;
Trierweiler 2010). On migration, Montagu´s Harriers encounter diverse hazards: they
have to cover ca. five thousand kilometers, stand sometimes unpredictable weather
conditions, cross barriers, and may be victims of illegal persecution, e.g. on Malta
(Raine 2007).
Montagu´s Harriers wintering ecology
Montagu´s Harriers from eastern breeding populations winter in India and eastern,
up to southern Africa, whereas birds from European populations migrate to the Sahel
in West Africa (Trierweiler & Koks 2009). Satellite telemetry revealed that individuals
use several traditional winter home ranges, which they revisit in consecutive years
(Trierweiler 2010). Investigations of the wintering sites in West Africa have been
conducted since 2006 by the Dutch Montagu´s Harrier Foundation (Trierweiler et al.
2006; Trierweiler et al. 2007a). In the wintering areas, Montagu´s Harriers feed
mainly on resident grasshoppers and therefore follow the green vegetation south
during winter. This was named the ‘green belt hypothesis’ (Trierweiler & Koks 2009;
Trierweiler 2010). Raptor counts in the Sahel showed an alarming decline in raptor
numbers between 1969 -73 and the beginning of the 21st century (Thiollay 2006).
Threats causing declines in resident as well as wintering raptor species are habitat
loss due to desertification and degradation, shortage of carcasses, poisoning for
predator control or persecution for trade of meat and body parts (Thiollay 2006). One
satellite tracked Montagu´s Harrier was trapped by a farmer, who believed that the
harriers endangered his chicken (Trierweiler et al. 2007b; Trierweiler & Exo 2009).
Summarizing, the Montagu´s Harrier is an appropriate study species to gain deeper
insight in the stopover ecology of raptors, because it is a long-distance migrant
wintering south of the Sahara, it is classified as threatened in some European
11
breeding areas where it is already the object of conservation practice, and it can be
fitted with satellite transmitters.
1.4 Study area: stopover site East-Morocco
Beside the detailed insights about migration routes and wintering areas mentioned
above (see 1.3., Montagu’s Harriers´ migrations and wintering ecology), satellite
tracking data yielded information on stopover sites and stopover behavior of
northwestern European individuals. Half way (ca. 2500 km) between Europe and
West Africa, the stopover area in East-Morocco is the only stopover site outside
breeding and wintering grounds (Trierweiler & Exo 2009). Other areas which are
used by Montagu´s Harriers during stopover lay in the breeding areas in Germany,
France and Spain. This can also be interpreted as prospecting (Trierweiler & Exo
2009).
During spring as well as autumn migration, noticeable concentrations of
tracked Montagu´s Harriers were found in East-Morocco and West-Algeria
(Trierweiler & Exo 2009; Trierweiler 2010; Fig. 3.2). The high plateaus of East-
Morocco were previously not known to lie on the migration route of Montagu´s
Harriers or to be an important stopover area (Clarke 1996; García & Arroyo 1998).
Thevenot et al. (2003) reported no observations of the species in this part of
Morocco, most probably due to a lack of observers. Regarding its position, the area
may be suitable for harriers that prepare themselves for the crossing of the Sahara
desert in autumn, as has been shown for trans-Sahara migrating passerines (e.g.
Bairlein 1991). An alternative function of the area may be awaiting favorable weather
conditions for the desert crossing. Supporting the latter is the observation that
Montagu´s Harriers on autumn migration returned to the stopover area after trying to
cross the Sahara and started again some days later (Trierweiler 2010), which has
also been shown for passerines (Deutschlander & Muheim 2009).
In spring, the area may act as refueling site after the crossing of the desert
and before the crossing of the Mediterranean, the migration through Europe and the
oncoming breeding season. This means that carry-over effects of ecological
conditions at this stopover site could influence the breeding success.
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Knowing not only which areas are valuable to preserve but also why they are
important is required to give management and conservation advice. To study the
ecological function and importance of the stopover site in East-Morocco for
Montagu´s Harriers, expeditions to this site were conducted during the spring and
autumn migration periods in 2010. This is the first time that stopover ecology of a
raptor species is specifically investigated on-site. In this thesis, results from these
field data will be combined with results from satellite tracking data of Montagu’s
Harriers to investigate Montagu’s Harrier stopover ecology in Northwest-Africa.
1.5 Research goals
To understand stopover ecology of migrating birds, three processes must be
examined: habitat selection, stopover duration, and weight change (Kerlinger 2009).
The first two aspects are studied for Montagu´s Harriers in this thesis.
The following questions were to be answered by doing fieldwork (FW) in East-
Morocco and combining the results with analyses of satellite telemetry data (STD):
• Position and importance of stopover areas in Northwest-Africa (FW, STD).
• How long do Montagu´s Harriers stay in Northwest-Africa during stopover
during spring and autumn migration (STD)?
• Are they site faithful to the stopover area in Northwest-Africa (STD)?
• What is the spatial distribution of Montagu´s Harrier in East-Morocco (FW,
STD)?
• Which habitats are used by Montagu´s Harriers in East-Morocco (FW, STD)?
• What are the main food sources of Montagu´s Harriers in East-Morocco
(FW)?
• What is the spatial distribution of potential Montagu´s Harrier prey species in
East-Morocco (FW)?
• Are there differences between spring and autumn stopovers?
• Which hazards may Montagu´s Harriers encounter in East-Morocco (FW)?
• What do the present findings imply with respect to conservation strategies?
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2. Materials and Methods
2.1 Satellite telemetry data
Since 2005 Montagu´s Harriers have been fitted with 9.5 g or 12 g solar satellite
transmitters (PTT-100, Microwave Telemetry Inc., Columbia, MD, USA) in an
international collaboration project (Trierweiler 2010). Data for analyses in this thesis
were obtained from 20 individuals using the western flyway via Spain (Appendix 1).
The data contained 50 migration tracks from 20 birds crossing Morocco between
2006 and 2010. Transmitters were programmed to either a 10:48 h on:off cycle or a
6:16 h cycle (Trierweiler et al. 2007b). The transmitters were attached using teflon-
ribbon backpacks and their weight did not exceed 5 % of total body mass of harriers
(Trierweiler et al. 2007b). Data were obtained from the Argos system via CLS
(Collecte Localisation Satellites, Toulouse, France).
For the present analyses, only fixes lying in Morocco (area see 2.2) were
selected. Bias can arise because of multiple fixes of one transmitter per day, or due
to regional differences in the frequency of satellite contact. To avoid this bias, per
individual only the best fix per day, indicated by Argos Location Class (LC; CLS
2008), was included in the analyses (Trierweiler & Klaassen in prep.). The fixes lying
in Morocco were categorized as stopover or travel days using the distance between
fixes on consecutive days as criterion. The threshold to distinguish between stopover
and travel fixes was set to a distance of 50 km between consecutive days
(Trierweiler & Klaassen in prep.; Trierweiler 2010). The resulting dataset was
checked graphically for outliers and consistency by plotting all location fixes in a
geographical information system (GIS).
The average sample size per stopover in Morocco was 6.62 ± 3.12 (SD) daily
fixes per bird for spring (n = 13 tracks) and 6.42 ± 3.73 daily fixes per bird for autumn
(n = 12). Therefore, calculation of individual home ranges - requiring a minimum of
20 fixes (Trierweiler in prep.; Trierweiler 2010) - was not possible. Instead, kernel
densities over stopover fixes of all individuals were calculated for spring and autumn,
respectively, revealing stopover areas used by multiple birds. From the kernel
volume contours the approximate size of the stopover areas was calculated. The
timing and duration of stopovers was analyzed considering the first stopover fix in
Morocco as arrival date and the last stopover fix as departure date. Site fidelity of
individual Montagu´s Harriers was determined visually.
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2.2 Location of the study area East-Morocco
Fieldwork was conducted during spring (9 - 22 April) and autumn migration (9 - 21
September) 2010 in East-Morocco (Fig. 2.1). In the following, the term ‘Morocco’ is
used to denote the Kingdom of Morocco including the southern provinces that form
the Western Sahara (Fig. 2.1B), an area of 884,905 km² in total. Our study area (Fig.
2.1C) was approximately 46,657 km² in spring and 80,510 km² in autumn. The area
covered was situated mainly between Oujda (34°40´N, 1°55´W) in the north and
Bouarfa (32°31´N, 1°57´W) in the south. In Septembe r 2010, we also proceeded in a
southwestern direction up to Errachidia (34°55´N, 4 °26´W).
The high plateaus of East-Morocco have an elevation between 1100 and 1400 m
above sea level and are dominated by steppe vegetation (Fig. 2.1D, for details see
2.3). This rather remote area of Morocco is, apart from few villages and towns,
inhabited by farmers and herdsmen living in tents and solitary farms.
Fig. 2.1: Study area East-Morocco. A: position of Morocco (yellow) in northwestern Africa. B:
position of covered area (shaded in red) in Morocco. C: detailed view of study area East-
Morocco (shaded in black). D: Halfa steppe, a typical landscape of the high plateaus of the
Moroccan East. Source: ESRI basemaps: World Physical Map (A, B), World Street Map (C).
15
2.3 Habitat characteristics of the study area East- Morocco
North Morocco has mainly a Mediterranean climate with hot and dry summers and
winter rains (Thevenot et al. 2003). Annual rain-fall is approximately 300 mm in the
east (Thevenot et al. 2003). Climax steppe vegetation is covering East-Morocco
(Thevenot et al. 2003; García et al. 2008). The high plateaus are sparsely covered
by this steppe dominated by Halfa grass (Stipa tennacissima) which grows in
tussocks reaching heights of up to ca. 1.5 m (here referred to as Halfa steppe). We
also visited areas where the steppe vegetation was dominated by Artemisia spp.,
hereafter called Artemisia steppe (see García et al. 2008). Artemisia plants are
obviously avoided by grazing livestock due to their content of repellent chemicals
(pers. comm. of a local forester). Other parts of steppe were dominated by Fredolia
aretioides, Anabasis articulata, Hammada scoparia, Noaea mucronata or were
covered by mixed vegetation. The steppes of East-Morocco were in some parts
interspersed with small patches of farmland. These were mainly cereal fields in the
eastern steppe regions and some pastures in the region close to Oujda (for regions
see 2.7, Fig. 2.3). On cereal fields, stems were sparse, mixed with other vegetation
and containing open spots.
Due to intensive grazing by sheep and goats, great parts of the area were
degraded, suffering first from shortened vegetation and in later stages from erosion.
To counteract erosion, the government of Morocco (through Eaux et Forêts)
manages the soil structure and plants shrubs (e.g. Atriplex spec.) in some restricted
areas. We categorized these areas as ‘anti-erosion’ areas during transect counts.
To record habitat characteristics quantitatively, we noted the percentage surface
area covered by grass/herbs, crop, stones and sand, the number of trees/ha and the
number of shrubs/ha. This was done during road transect counts (see 2.5, Fig. 2.2)
to gain reference data on habitat types. During prey transect counts (see 2.7, Fig.
2.3), additionally the height of grass/herbs and crop was estimated.
16
The following habitat types were classified during transect counts:
• F – farmland (cereal fields in spring, plowed fields in autumn)
• V – villages and towns
• AE- anti-erosion (plantation of shrubs e.g. Atriplex spec., trees e.g. eucalyptus
or conifers, or working the soil for reducing erosion)
• N – natural steppe with different vegetation communities e.g. Fredolia
aretioides, Anabasis articulata
• NH – natural steppe dominated by Halfa grass Stipa tennacissima
• NA – natural steppe dominated by Artemisia spec.
• T – trees (coniferous woods in mountainous regions e.g. Juniperus spec.)
• R – rocks (stony hillsides or desert)
• S – sand
• O – oasis (only categorized as such during the autumn expedition)
• W – wadi (along or in a wadi)
• D – depression (depressed area with green vegetation, often salt tolerant
plants or farmland; called ‘ex-lac’, because they are flooded irregularly)
• Combinations of two of the habitat types in transition zones.
Whenever we noted habitat type and other habitat characteristics, we also
determined the degree of degradation according to the following broad categories:
• 0 – intact landscape, no signs of overgrazing or erosion
• 1 – little degradation, signs of overgrazing and erosion
• 2 – much degradation, strong overgrazing and erosion
• 3 – total degradation, bare soil due to overgrazing, strong erosion.
17
2.4 Loose observations and localization of roosts
All observations of Montagu´s Harriers and other raptor species, also outside
transect counts, were noted during the trips with exact geographical position and
habitat information. If possible sex and age of Montagu´s Harries were determined
and noted. Only observations where sex and age could be determined exactly were
used for sex ratio calculations and age classes.
The roost encountered in spring close to Ain Benimathar could be located by
tracking a satellite tagged Montagu´s Harrier sleeping at this roost close to real time.
An additional roost of two individuals was found northeast of Ain Benimathar on the
high plateau, also using satellite tracking information. In autumn, we observed a
roost containing about six Montagu´s and 15 Marsh Harriers located south of
Taourirt. The roost observed in autumn was found during systematic (road transect)
scans of large areas of East-Morocco. To show the distribution and abundance of
migrating Montagu´s Harriers throughout Morocco, I plotted all our observations in a
map (see 3.2, Fig. 3.5). Additionally, I plotted all observations mentioned with clear
location descriptions in Thevenot et al. (2003) in the same map.
2.5 Road transect counts
For estimating distribution and abundance, all raptor species were counted along
roads and paths while driving with a maximum speed of 80 km/h (Thiollay 2006;
Trierweiler et al. 2007a). The mean speed was considerably lower due to the quality
of roads. Additionally, the habitat type and the degradation state of the landscape
were noted every 5 km as described above (see 2.3). Habitat characteristics were
also noted when a raptor was spotted, together with noting the exact geographic
position by making a GPS waypoint. We drove 2043 and 2250 km of road transects
in spring and autumn, respectively (Fig. 2.2). We also estimated the distance of
observed birds to the road at the point they were first seen. For our standardized
forms see Appendix 2.
18
Fig. 2.2: Road transects in East-Morocco covered in spring and autumn 2010, respectively,
and Montagu´s Harriers observed during road transect counts (red symbols). Size of symbols
refers to number of harriers observed at a location. Source: ESRI basemap: World Street
Map.
2.6 Habitat selection
Satellite telemetry data and Globcover digital land cover map
To estimate habitat availability in stopover areas in comparison to a larger reference
area, a digital global land cover map was used. Globcover (Globcover Source Data:
© ESA / ESA Globcover Project, led by MEDIAS-France/Postel) is a global land
cover map with a spatial resolution of 300 m. It contains 22 global land cover classes
which are defined within the UN Land Cover Classification System (LCCS).
Globcover was derived from classification of a time series of satellite images
covering the period December 2004 - June 2006 and has an accuracy level of 67.10
% (Bicheron et al. 2008).
The digital map was intersected with home range contours from stopover
sites instead of with individual location fixes to minimize bias due to location fix
errors (Trierweiler 2010, Box D). First, Morocco was used as reference area
19
(excluding the Western Sahara or southern provinces, but including a part of Algeria
to cover the whole stopover area; see blue polygon Fig. 3.10). To test on a smaller
scale if the habitat composition at the stopover sites differs from that of a reference
area, the home range contours were intersected with two smaller reference areas:
one in western Morocco and one in eastern Morocco (see black polygons Fig. 3.10).
To estimate the goodness of inferences on habitat availability and use, ground
truthing was conducted. Therefore the habitat types noted at 1316 prey transect start
and end points from our spring and autumn trips were compared to Globcover raster
cell values.
Own observations and reference habitat classifications: Field data
To analyze habitat selection of Montagu´s Harriers during stopover in East-Morocco,
I used all observations of individuals during road and prey transect counts (see 2.7),
at roosts and loose observations. The habitats used by Montagu´s Harriers were
compared to the total amount of available habitat of each category obtained through
reference habitat classifications noted every 5 km during road transect counts. The
analysis was conducted over six habitat types for which enough references were
available (contributing >4 % to available habitat of all road transect references,
except for Artemisia steppe in autumn with only 1.8 %). The separate calculation for
roosting individuals contained only four habitat types (farmland, natural steppe,
Artemisia steppe, Halfa steppe) due to the small sample size.
2.7 Prey transect counts
To estimate the abundance of potential prey for Montagu´s Harriers in the stopover
area and in different habitat types, we conducted standard prey transect counts by
foot (Trierweiler 2006; Trierweiler et al. 2007a). This method was used in the
wintering areas by Altenburg & Wymega during transect counts in Mali, Senegal and
Guinea Bissau (Trierweiler et al. 2007a; Zwarts et al. 2009) and by now is used by B.
Arroyo in India and by V. Bretagnolle in Senegal. While walking through a
homogenous area of one habitat type, all birds 30 m left and right of the transect line
were recorded and, if possible, determined to species level. All mammals, reptiles
and amphibians were also noted in that transect. Two meters to both sides of the
imaginary transect line, all large insects (locusts < 3 cm, 3-7 cm, > 7 cm; beetles < 1
20
cm, 1-2 cm, > 2 cm) and active holes of mammals (Ø ≤ 3 cm, Ø = 4-10 cm, Ø > 10
cm) and reptile holes (only in autumn) were noted. Reptile holes could be
distinguished by their flat, squared appearance. Birds passing by over the transect
were noted separately. All songbirds and birds smaller in size than doves were
categorized as potential prey for Montagu´s Harriers, thereby excluding e.g. raptor-,
wader-, and shrike species. For each prey transect, GPS waypoints were taken at
the beginning and end of the line. Furthermore, information on the habitat type of the
transect was collected (see 2.3 for details). For our standardized forms see Appendix
3.
During the two excursions in 2010, we counted 658 prey transects with a total
length of 294.85 km (Fig. 2.3). In spring, 267 prey transects were counted with a total
length of 120.56 km. The average length was 0.45 km ± 0.28 (min: 0.06 km, max:
1.77 km). In autumn 2010, 391 prey transects were counted with a total length of
174.29 km. The average length was 0.45 ± 0.31 km (min: 0.04 km, max: 2.6 km). To
look for regional differences in prey abundance, I divided the study area in 11
regions, based on the dominant vegetation and landscape types in these areas (Fig.
2.3).
The Shannon-Weaver diversity index is a concept of diversity, i.e. of the distribution
of observations among categories (Zar 1996):
�´ = − � �� ln ���
� �
Where k is the number of species and pi is the proportion of individuals found in
species i.
Here it is used to calculate the distribution of individual potential prey birds among
species. If the individuals are evenly distributed over the species the diversity is high,
if nearly all individuals belong to the same species it is low. Normally values lie
between 1.5 and 3.5. The Shannon-Weaver diversity index was calculated for
potential prey bird species in spring and autumn to compare seasons and for the 11
regions to find spatial differences.
21
Since not only the distribution of individuals among species influences H’ but also the
number of species, the evenness was also calculated (Zar 1996):
�´ = �´ln (�)
The evenness expresses the observed diversity as a proportion of the maximum
possible diversity and may be referred to as homogeneity or relative diversity (Zar
1996). It takes a value between 0 and 1, with higher values indicating a more even
distribution of individuals among species.
The dominance structure of potential prey species is the relative abundance of a
species in comparison to other species (Townsend et al. 2002):
��������� = �� ∗ 100�
Where ni is the number of individuals of species i and N the total number of
individuals. A species is considered subrezedent if the dominance <1 %, rezedent if
it is 1 - 2 %, subdominant if it is 2 - 5 % or dominant if it is 5 - 10 %.
Shannon-Weaver diversity index, evenness and dominance were calculated
considering only individuals determined to species level inside transects, i.e. birds
flying over the transect were left out.
22
Fig. 2.3: Position of prey transects (dots) in East-Morocco in spring and autumn 2010
distributed over eleven regions (red: region number, black: region name). Regions are
separated according to common landscape characteristics. Source: ESRI basemaps: World
Physical Map.
23
2.8 Pellet analysis
To gain insight in food choice during stopovers, pellets (undigested, regurgitated
prey remains, including bones, fur, feathers, etc.) were collected at roosts. Each
pellet was stored separately in an envelope, dried and stored at room temperature
for 7 months. Each pellet was weighed to the nearest 0.01 g and length and width of
the largest fragment were measured with calipers to the nearest 0.1 mm. The
difference between pellets of Montagu´s and Marsh Harriers is mainly in size, with
Montagu´s Harriers producing smaller pellets. In the field the difference could be
clearly seen from the size of the open spot where the bird was sleeping and the
distance between pellets and droppings at the sleeping place of the bird. The mean
mass of pellets of Montagu´s Harriers (n = 21) was 1.59 g and mean length and
width were 30.9 and 15.6 mm, respectively.
For determination of contents, pellets were dissected and prey items
identified. The determination of prey to species level was not possible, but items
were sorted into higher taxon categories (mammals: hair, bones; reptiles: scales,
bones; birds: eggs, feathers, bones; beetles; plant material). We estimated the
volume percentages of each prey category of a pellet and weighed the different
fractions separately. The number of individuals of each category was determined
using countable fragments: jaws of mammals, bills of birds, heads of beetles (Arroyo
1997; Trierweiler 2010, Box A). If only uncountable remains of prey items were
present, the minimum number of individuals per pellet was set to one.
We multiplied the number of individuals of each category with a fresh (wet) weight
value of an individual for calculating the proportion of biomass each category
contributed to the diet represented in the pellets. Weight values were derived by the
following calculations and considerations.
The pellets contained many egg shell fragments. Because the most abundant
breeding birds were several lark species and we also found several lark nests,
measurements of lark eggs were used for calculations. The weight of lark eggs could
not be determined in the field.
24
Therefore, using the length and width measurements of eggs given in Harrison &
Castell (2004) for 12 lark species (Appendix 4), the weight of eggs was estimated
according to (Hoyt 1979):
� = � ∗ !"#,
where W = weight, Kw = constant, L = length and B = breadth.
Kw is a species-specific weight coefficient that must be determined empirically or
can be derived from literature values of W, L, and B (Hoyt 1979).
� = �$�%/!$�%"$�%²
For this calculation, we used mean values of four lark species from literature: Short-
toed Lark (Calandrella brachydactyla), Lesser Short-toed Lark (Calandrella
rufescens), Crested Lark (Galerida cristata) and Calandra Lark (Melanocorypha
calandra). Mean values for these were: Wlit = 2.9 g, Llit = 21.5 mm, Blit = 16.0 mm
(Glutz von Blotzheim & Bauer 1985).
According to these formulas, the mean weight of a lark egg was estimated as
3.4 g. Since the egg shell accounts for 6 % of the total weight of an egg (BTO Bird
Facts, Shore Lark: http://blx1.bto.org/birdfacts/results/bob9780.htm, 11.11.2010), the
estimated weight of the shell of one egg was considered 0.2 g. This value can also
be found for lark eggs of several individual species (Glutz von Blotzheim & Bauer
1985). Therefore, the number of eggs present in a pellet was estimated by dividing
the total weight of shell fragments by 0.2 g.
For birds, the weight was derived from the mean value of adult birds of four
lark species which were common in the area (see Fig. 3.17; Short-toed Lark, Lesser
Short-toed Lark, Crested Lark and Calandra Lark, mean = 39 g) and nestlings of two
species (Crested and Short-toed Lark, mean over whole nestling period = 11.4 g).
During the spring expedition we observed nestlings and adults with prey regularly.
Making the assumption that half of the prey birds were adults and half nestlings, the
estimated weight of a bird was 25 g.
Estimating the weight of small mammals is constrained, because we could
not confirm during fieldwork which species occur in the study area. The assumed
25
weight of small mammals was set to 23 g, the body mass of a Small Egyptian Gerbil
(Gerbillus gerbillus; http://www.gerbil.info/html/othergerbillus.htm, 03.03.2011).
Since the observed reptiles during prey transects were mainly lizards with a
length of about 7 cm, the weight of reptiles was assumed to be 3.2 g (Meiri 2010).
To define a rough estimate of beetle weights, 1 g, the weight of Calosoma
sycophanta (Coleoptera, Carabidae) from Turkey was used as a representative of
ground beetles (length of freshly emerged adult 2 cm; Kanat & Özbolat 2006).
2.9 Spatial and statistical analyses
All maps in this thesis were produced using ArcMap 9.3 (ESRI 2008) and were
projected in UTM 32N. Encounter probabilities were calculated using the Kernel
density tool of the Spatial Analyst extension in ArcMap. The h-value was estimated
using R 2.12.0 (R Development Core Team 2010).
Stopover durations in spring and autumn and between years were compared using
ANOVA. To test if the sex ratio differed from 1:1 a Chi-square Test was conducted.
Day time dependent variation in raptor observations was tested using ANOVA. The
comparisons of habitat availability in stopover areas and reference areas were
conducted using Chi-square Tests. Habitat preferences of observed Montagu´s
Harriers were calculated using the function compana in R (Callenge 2006). To test
the influence of different parameters on the number of potential prey birds a General
Linear Model (GLM) was calculated. The model contained the parameters season,
time, habitat, degradation, length, observer, the interactions of habitat and
degradation, time and length, season and habitat, and season and degradation. The
best model was fitted by removing first non-significant interactions, then non-
significant parameters. Another GLM with the parameters season, region, and length
was calculated to test for spatial variation in potential prey bird abundance. In both
cases length was kept as variable to correct for the influence of transect length. The
proportions of prey items according to estimated volume and weighed proportions in
pellets were compared using Fisher´s Exact Test. The average proportion based on
number of prey items counted in pellets and estimated biomass of the same
category was also compared using Fisher´s Exact Test.
All statistical tests were conducted in R. All tests were two-tailed. The significance
level was set to α = 0.05.
26
3. Results
3.1 Montagu´s Harriers´ stopover sites in East-Moro cco and their use as
revealed by satellite telemetry
Locations of stopovers
Analyzing satellite data of 20 tagged Montagu´s Harriers crossing Morocco between
2006 and 2010 revealed that there were several important regions for stopover
during spring and autumn migration (Fig. 3.1 and 3.2A). Satellite tracks (shortest
connections between consecutive daily satellite fixes of tracked birds) through
Morocco showed that harriers mainly travel on a northeast-southwest axis through
the country. In East-Morocco, several tracks showed high turning rates, which
indicate the use of the area as a stopover site, because birds stayed several days in
the area. This is confirmed by low travel rates (stopover days, <50 km/day covered)
in this area. On average, half of the harriers stopped over in Morocco while migrating
on a western route via Spain between the European breeding and Sahelian wintering
areas in autumn and spring (Table 1). During autumn migration, 41 % of migrating
individuals used stopover sites in Morocco. During spring migration, Morocco was
even of greater importance with 76 % of tracked Montagu´s Harriers stopping over.
Analyzing stopover fixes in detail revealed two main stopover areas of
Montagu´s Harriers in Morocco. While the western region was only important during
spring migration, East-Morocco showed high encounter probabilities in both seasons
(Fig. 3.2A). The same was true for the year 2010 analyzed separately, when the two
field trips were conducted (Fig. 3.2B). In spring 2010, three satellite tagged
Montagu´s Harriers stopped over in Morocco: Danish adult female Mathilde and
Danish adult male Michael used the western stopover region (length of stay: 14 and
5 days, respectively), whereas Dutch adult male Franz stopped over in East-
Morocco, where we also managed to observe him in the field (length of stay: 12
days). In autumn 2010, Mathilde made a 2-day stop on a plateau (altitude about
1500 m) with agricultural fields about 130 km southeast of Marrakesh and about 10
km west-southwest of Tazenakht. This stop was not in one of the major stopover
areas. Klaus-Dieter in contrast, used the region in East-Morocco, where we
observed him during his 11-day stopover.
27
Table 1: N: Number of satellite tagged northwest European Montagu´s Harriers migrating on a western migration route via Spain in
spring (season S) and autumn (season A). N stopover: number of individuals stopping over in Morocco. % stopover: percentage of all
birds (N) making stopovers in Morocco.
year 2006 2007 2007 2008 2008 2009 2009 2010 2010 2007-2010 2006-2010 all
season A S A S A S A S A S A
N 5 4 8 6 4 3 5 4 7 17 29 46
N stopover 3 3 2 4 2 3 3 3 2 13 12 25
% stopover 60 75 25 67 50 100 60 75 29 76 41 54
27
28
Fig. 3.1: Fifty tracks of 20 satellite tagged northwest European Montagu´s Harriers crossing
Morocco during spring and autumn migration between 2006 and 2010. Lines connect best
fixes per day of each track within Morocco (see methods). Different colors represent different
tracks. Inset map shows close up view of East-Morocco.
29
Fig. 3.2: Satellite fixes of tracked Montagu´s Harriers stopping over in Morocco in spring and
autumn, respectively. Included is only the best fix per day. Green and red points equal fixes. Blue
areas show encounter probabilities >0.00003 as kernel densities. Stopover areas are encircled in
green for spring and in red for autumn. A: Spring 2007 - 2010 (n = 99 fixes, N = 9 birds, n = 14
tracks) and autumn 2006 - 2010 (n = 121, N = 10, n = 13). B: Spring 2010 (n = 29 fixes, N = 3 birds)
and autumn 2010 (n = 13, N = 2).
30
Timing and duration of stopovers
Montagu´s Harriers arrived in Morocco on average on 12 April and departed on 19
April in spring (Table 2). In autumn, they arrived on average on 17 September and
departed on 23 September (Table 2). The duration of 25 stopovers during spring and
autumn migration in Morocco ranged from 2 to 20 days (data: 2006 - 2010, Table 3).
On average it was 9.2 ± 4.56 (SD) days. The stopover duration did not differ
significantly between spring (n = 13) and autumn (n = 12; 9.69 ± 3.71 (SD) days vs.
8.67 ± 5.45 (SD) days, ANOVA, F = 0.011, p = 0.891). The duration of stopovers
was not significantly different between years (2006 - 2010, F = 0.101, p = 0.754).
Examining the timing of individual Montagu´s Harriers stopping over in Morocco in
consecutive years indicated individual differences. Tracked adult male Franz for
example made stopovers in Morocco during spring migration 2007, 2009 and 2010
(Table 3). Twice, he arrived on 6 April and once on 10 April, always before the
average arrival date. On average, he stopped for ca. 11 days. In spring 2008, he
crossed Morocco but did not stop at all. This was also the case for all his 5 autumn
migrations between 2006 and 2010. In contrast, tracked adult female Merel, tagged
in 2006, made stopovers in Morocco on each of her migration trips from autumn
2006 to spring 2009 (Table 3). The duration of her stops varied between 2 and 11
days.
31
Table 2: Mean arrival date and standard deviation (number of days) of arrival and departure dates
of 20 satellite tagged northwest European Montagu´s Harriers´ stopovers in Morocco during spring
and autumn migration, 2006 - 2010 (n = number of individuals).
arrival departure arrival departure
spring mean sd mean sd n autumn mean sd mean sd n
2006 20-Sep 10 28-Sep 19 3
2007 11-Apr 13 18-Apr 8 3 2007 9-Sep 1 19-Sep 1 2
2008 12-Apr 8 21-Apr 5 4 2008 24-Sep 6 3-Oct 15 2
2009 14-Apr 15 16-Apr 3 4 2009 15-Sep 15 18-Sep 14 4
2010 12-Apr 6 21-Apr 4 3 2010 17-Sep 8 22-Sep 1 2
all 12-Apr 10 19-Apr 5 14 all 17-Sep 9 23-Sep 13 13 aSatellite tagged juvenile male Jurek arrived in spring 2009 but stayed the whole summer in East-Morocco. Therefore, the sample size for departure spring 2009 and arrival autumn 2009 was only 3. Because he arrived in spring 2009 and departed in autumn 2009, his dates are included and there the sample size is 4.
Table 3: Arrival and departure date and duration of stopover in days for 13 satellite tagged
northwest European Montagu´s Harriers stopping over in Morocco. No duration of stopover is given
for Jurek, because he stayed the whole summer 2009 in Morocco and Algeria. For details about
individual harriers see Appendix 1.
spring autumn bird arrival departure duration bird arrival departure duration
2007 2006 Franz 6-Apr 14-Apr 9 Freyr 30-Sep 19-Oct 20 Merel 16-Apr 17-Apr 2 Merel 17-Sep 22-Sep 6 Tania 2-Apr 14-Apr 13 Tania 12-Sep 13-Sep 2 2008 2007 Doris 8-Apr 17-Apr 10 Jinthe 10-Sep 20-Sep 11 Edzard 3-Apr 16-Apr 14 Merel 8-Sep 18-Sep 11 Margret 22-Apr 27-Apr 6 2008 Merel 11-Apr 21-Apr 11 Jochen 27-Sep 12-Oct 16 2009 Merel 18-Sep 21-Sep 4 Cathryn 1-Apr 13-Apr 13 2009 Franz 10-Apr 18-Apr 9 Iben 1-Oct 7-Oct 7 Jurek 5-May Jurek 8-Sep 37 Merel 8-Apr 15-Apr 8 Mathilde 2-Sep 7-Sep 6 2010 Remt 11-Sep 18-Sep 8 Franz 6-Apr 17-Apr 12 2010 Mathilde 12-Apr 25-Apr 14 Klaus-Dieter 11-Sep 21-Sep 11 Michael 17-Apr 21-Apr 5 Mathilde 22-Sep 23-Sep 2
32
Size of stopover areas
The size of the stopover area in East-Morocco calculated from kernel density volume
contours of stopover fixes was 21,400 km² (50 % volume contour) and 32,800 km²
(90 % volume contour) in spring and 17,400 km² (50 %) and 26,500 km² (90 %) in
autumn (Fig. 3.3). The area used in the west during spring migration had a size of
36,800 km² (50 %) and 51,400 km² (90 %).
Fig. 3.3: Main stopover areas of 20 satellite tracked Montagu´s Harriers in Morocco (2006 –
2010; see also Fig. 3.2). Red lines indicate 50 % (inner) and 90 % (outer) volume contours of
kernel densities. Because Montagu´s Harriers only use land for stopover, the oceanic part of
the western stopover area was cut off, resulting in an irregular shape of the 90 % kernel
density volume contour. Spring west n = 28 fixes, N = 4 birds, n = 4 tracks; spring east n =
47, N = 5, n = 7; autumn east n = 75, N = 6, n = 8.
33
Site fidelity
Ten satellite tagged Montagu´s Harriers stopped in Morocco both during spring and
autumn migration (2006 – 2010). From three of those birds, data on multiple
stopovers in different years are available (Fig. 3.4).
Dutch adult male Franz stopped over in the eastern spring stopover area in
2007, 2009 and 2010 (Fig. 3.4 left). Within this area, he used a site close to Ain
Benimathar in spring 2009 and 2010. In 2007 and 2010, he also stopped over at a
site on the Maatarka plateau. In spring 2007, he visited additionally the border area
with Algeria east of Tendrara.
Danish adult female Mathilde, on the other hand, did not use the same
stopover site in two subsequent years (Fig. 3.4 centre). She also stopped on the high
plateaus north of Maatarka in autumn 2009. In spring 2010, she stayed several days
in the western spring stopover site around Youssoufia and visited a second site near
Settat. In autumn 2010, she only made a brief stop about 10 km west-southwest of
Tazenakht.
Like Franz, Dutch adult female Merel showed great site fidelity to East-
Morocco (Fig. 3.4 right). In spring 2007, she stayed close to Ain Benimathar. In
spring 2008 as well as autumn 2006 – 2008, Merel used a stopover site west of
Tendrara. In autumn 2006, she additionally visited a site near Boudnib. In autumn
2007, she also made a second stop in western East-Morocco, 120 km north of
Errachidia and 50 km east of Midelt. Only in spring 2009, she stopped somewhere
very different, in the south of Morocco just north of the Sahara desert near Tan-Tan.
34
Fig. 3.4: Stopover areas of three satellite tagged northwest European Montagu´s Harriers stopping over during migration in Morocco.
Shown are daily best satellite fixes during stopover. Stopover areas used by several satellite tagged Montagu´s Harriers (see Fig. 3.3)
are illustrated by 50 % (inner) and 90 % (outer) volume contours of kernel densities. Green lines refer to spring and red lines to
autumn stopover areas. Note the different scales.
34
35
3.2 Distribution and abundance of Montagu´s Harrier s in East-Morocco: field
data
Knowledge of distribution and abundance of Montagu´s Harriers in Morocco has
been scarce and fragmentary with a bias to the west of Morocco (Thevenot et al.
2003; Fig. 3.5). The only scientific expedition which conducted systematic counts
investigating larks in eastern Morocco also observed Montagu´s Harriers regularly
(Jesús T. García, pers. comm.: region around Ain Benimathar 19 individuals in
spring 2010, region around Midelt, north of Errachidia, 7 individuals). During both of
our field trips to Morocco, all Montagu´s Harriers observed during prey or road
transect counts plus all the loose observations outside transects, e.g. at roosts, are
summed to show the abundance of harriers in East-Morocco during spring and
autumn migration, respectively (Fig. 3.6). The high concentration of individuals south
of Ain Benimathar in spring results from a nighttime roost visited several times. At
this roost, approximately 10 Montagu´s and 10 Marsh Harriers slept in an agricultural
field on the ground.
The number of Montagu´s Harriers observed was higher in spring (73) than in
autumn (11). The sex ratio was 0.9 in spring and 1.3 in autumn and not significantly
different from 1.0 (Chi-square Test: spring: p = 0.535; autumn: p = 0.739; Fig. 3.7). In
total, the number of adult birds observed (66 %) was higher than the number of
younger birds (15 %).
36
Fig. 3.5: Observations of breeding and migrating Montagu´s Harriers in Morocco according to
Thevenot et al. 2003 complemented with own observations made during two field trips in
spring and autumn 2010.
Fig. 3.6: Abundance of Montagu´s Harriers in East-Morocco during spring (n = 73) and
autumn (n = 11) 2010, respectively. Included are all individuals seen during road and prey
transect counts and loose observations. Blue areas show encounter probabilities as kernel
densities. Lines stand for the 90 % (outer) and 50 % (inner) volume contours of the kernel
density.
37
B
female male
num
ber
of M
onta
gu´s
Har
riers
0
2
4
6
8
10
adjuvn.a.
A
female male
num
ber
of M
onta
gu´s
Har
riers
0
10
20
30
40
Fig. 3.7: Number of Montagu´s Harriers observed in spring (A, n = 65) and autumn (B, n = 9)
2010, according to sex and age. Included are all loose observations and observations during
road and prey transect counts where the sex of individuals could be exactly determined. n.a.
= age class could not be identified. Note the different scales.
Road transects
In total, we observed 228 raptors during road transect counts (Table 4). The 91
raptors in spring belonged to 11 species, the 137 raptors in autumn belonged to 16
species. Griffon Vultures were only observed in spring, whereas Osprey, Honey
Buzzard, Sparrowhawk, Black-winged Kite and Bonelli´s Eagle were only seen in
autumn. Little Owls were not encountered during road transects in spring, but were
common in autumn. A complete list of all species seen during both trips can be found
in Appendix 5. Montagu´s Harriers were only observed three and six times during
road transect counts in spring and autumn, respectively (see Fig. 2.2).
The overall number of raptors per 100 kilometer road transect was 5.3 (Table 4). Per
100 km transect, 0.1 Montagu´s Harriers were observed in spring and 0.3 in autumn.
The average distance within which counted raptors were located from the
road was 131 ± 162 (SD) m. 92 % of observations lay at a maximum distance of 400
m from the transect line (Fig. 3.8). Raptors could be observed during the whole time
of daylight (Fig. 3.9). The high value from 7:00 – 8:00 h is based on a very few
observation minutes. Otherwise, there was no indication of daytime dependent
variations which could be expected e.g. during the hottest time of the day (ANOVA, F
= 2.27, p = 0.150).
38
Table 4: Number of raptor species seen during road transect counts and number of individuals per 100 km transect in spring and
autumn 2010.
Scientific name English name German name Dutch name spring autumn
n n/100 km n n/100 km Gyps fulvus Griffon Vulture Gänsegeier Vale Gier 2 0.1 0 0.0 Pandion haliaetus Osprey Fischadler Visarend 0 0.0 1 0.0 Aquila chrysaetos Golden Eagle Steinadler Steenarend 2 0.1 2 0.1 Circaetus gallicus Short-toed Eagle Schlangenadler Slangenarend 2 0.1 5 0.2 Hieraaetus pennatus Booted Eagle Zwergadler Dwergarend 1 0.0 10 0.4 Aquila fasciata Bonelli´s Eagle Habichtsadler Havikarend 0 0.0 2 0.1 Milvus milvus Black Kite Schwarzmilan Zwarte Wouw 2 0.1 3 0.1 Circus aeruginosus Marsh Harrier Rohrweihe Bruine Kiekendief 11 0.5 14 0.6 Circus pygargus Montagu´s Harrier Wiesenweihe Grauwe Kiekendief 3 0.1 6 0.3 Buteo rufinus Long-legged Buzzard Adlerbussard Arendbuizerd 1 0.0 25 1.1 Pernis apivorus Honey Buzzard Wespenbussard Wespendief 0 0.0 1 0.0 Accipiter nisus Sparrowhawk Sperber Sperwer 0 0.0 2 0.1 Elanus caeruleus Black-winged Kite Gleitaar Grijze Wouw 0 0.0 1 0.0 Falco tinnunculus Kestrel Turmfalke Torenvalk 20 1.0 10 0.4 Falco naumanni Lesser Kestrel Rötelfalke Kleine Torenvalk 38 1.9 21 0.9 Falco biarmicus Lanner Falcon Lannerfalke Lannervalk 6 0.3 9 0.4 F. tinnunculus/naumanni Kestrel/Lesser Kestrel Turm/Rötelfalke Toren/Kleine Torenvalk 3 0.1 7 0.3 Falco spec. 0 0.0 1 0.0 Raptor spec. 0 0.0 7 0.3 Athene noctua Little Owl Steinkauz Steenuil 0 0.0 10 0.4 sum 91 4.5 137 6.1
38
39
distance from the road [m]
0 100 200 300 400 500 600 700 800 900 1000
num
ber
of r
apto
r ob
serv
atio
ns
0
20
40
60
80
Fig. 3.8: Frequency distribution of the distance from the road transect line of raptor
observations (n = 195) in East-Morocco 2010.
Fig. 3.9: Number of raptors observed during road transects in the course of the day (local
time = UTC). Given above are the number of days during which transects were counted and
the total observation minutes per hour of the day. Dark grey bars indicate approximately
sunrise and sunset.
hours of the day
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
num
ber
of r
apto
rs/h
our
0
5
10
15
20
25
30
17
6191
17429
20550
21625
21675
21524
23840
22730
14428
797
229
number of dayssum minutes
40
3.3 Habitat selection during stopover
Satellite telemetry data and Globcover digital land cover map
A comparison of stopover sites used by Montagu´s Harriers with Morocco as
reference area (excluding southern provinces, but including a part of Algeria to cover
the whole stopover area; blue polygon in Fig. 3.10) showed that habitats (Globcover
land cover categories) were not chosen randomly (Fig. 3.11). Habitat composition in
the three stopover areas (spring west, spring east, autumn east; see Fig. 3.3)
differed significantly from the habitat composition of the reference area (Chi-squared
test for 12 habitat types with an availability in Morocco >2 %; reference area vs.
spring east: χ² = 23.923, df = 11, p = 0.013; reference area vs. spring west: χ² =
47.006, df = 11, p < 0.001; reference area vs. autumn east: χ² = 48.793, df = 11, p <
0.001; Fig. 3.10 and 3.11). In the eastern stopover area, in spring and autumn, the
land cover category ‘bare areas’ was overrepresented compared to the reference
area (Fig. 3.11B,C). All other categories were underrepresented in the stopover area
compared to the reference area. In the western spring stopover area, the vegetation
categories ‘rainfed cropland’, ‘mosaic cropland/vegetation’ and ‘sparse vegetation’
were overrepresented compared to the reference area (Fig. 3.11A). ‘Bare areas’,
‘closed to open shrubland’ and ‘mosaic vegetation/cropland’ were underrepresented
in the stopover area compared to the reference area.
To test if preferences were also consistent on a smaller scale level, I divided the
reference area in an eastern and a western part (Fig. 3.10 black polygons). The
presence of different habitat types at the spring stopover site in the west did not
differ significantly from the abundance in the western reference area (χ² = 17.370, df
= 11, p = 0.097; Fig. 3.12). Nevertheless, there was a trend of harriers using areas
with ‘rainfed cropland’, ‘mosaic cropland/vegetation’ and ‘sparse vegetation’ more
than proportionally available, unlike the other land cover categories.
The habitat composition at the spring stopover site in the east did not differ
significantly from the eastern reference area (χ² = 7.086, df = 11, p = 0.792, Fig.
3.12). In autumn, there was a significant difference between the habitat present at
the stopover site compared to the eastern reference area (χ² = 25.686, df = 11, p =
0.007; Fig. 3.12). Then, harriers used an area where the category ‘bare areas’ was
overrepresented compared to the eastern reference area. Other habitat categories
were used to a lesser extent than proportionally available in the reference area.
41
To estimate how good inferences on habitat availability and use based on the
Globcover map are, ground truthing with prey transect habitat categories was
conducted. For 1316 prey transect start and end points from our spring and autumn
trips, the value of the Globcover raster was obtained and compared to the habitat
type noted in the field (Fig. 3.13). For Globcover raster cell values denoting different
types of agricultural land, we always categorized vegetation during prey transect
counts as farmland. But these were only 6 % of transects we noted as farmland. For
94 % of what we also noted as farmland, Globcover gives values for ‘mosaic forest-
shrubland/grassland’ (1 %) ‘sparse vegetation’ (27 %) or ‘bare areas’ (65 %). ‘Mosaic
forest-shrubland/grassland’ was in the field mainly determined as ‘depression’ (64
%), as ‘farmland’ (14 %), or a mixture of both (18 %), and once as ‘natural steppe’ (5
%). In the field, we designated the Globcover category ‘closed to open shrubland’
always as our category ‘trees’. We classified ‘sparse vegetation’ mainly as ‘farmland’
(40 %), ‘Halfa steppe’ (23 %) and ‘natural steppe’ (20 %), as well as some other
categories. The Globcover type ‘bare areas’ also consisted in the field of many
categories, mainly ‘natural steppe’ (45 %), ‘Halfa steppe’ (19 %), ‘farmland’ (12 %)
and ’Artemisia steppe’ (7 %).
42
Fig. 3.10: Reference areas for comparison of habitat composition. Blue polygon: Morocco,
excluding southern provinces and including a small part of west Algeria. Reference areas
west and east Morocco are lined in black. Green lines encircle spring stopover sites and red
lines the autumn stopover site. Lines indicate 50 % (inner) and 90 % (outer) volume contours
of kernel densities of Montagu´s Harrier fixes in stopover areas between 2006 and 2010.
43
Fig. 3.11: Habitat availability in the whole reference area (black, see Fig. 3.4) compared to
habitat in the three stopover areas (grey, Fig. 3.3) for the most important Globcover land
cover types (availability in Morocco >2 %). A: spring west, B: spring east and C: autumn east.
Fig. 3.12: Habitat availability in the two reference areas east and west (black, see black lined
areas in Fig. 3.4) compared to habitat in the stopover areas (grey) in the east (spring and
autumn) and west (spring) for the most important Globcover land cover types (availability in
Morocco >2 %).
Habitat percentages [%]0 20 40 60 80 100
availableused
Habitat percentages [%]0 20 40 60 80 100
Rainfed croplands
Mosaic croplands/Vegetation
Mosaic vegetation/Croplands
Mosaic Forest-Shrubland/Grassland
Closed to open shrubland
Sparse vegetation
Bare areas
Habitat percentages [%]0 20 40 60 80 100
Rainfed croplands
Mosaic croplands/Vegetation
Mosaic vegetation/Croplands
Mosaic Forest-Shrubland/Grassland
Closed to open shrubland
Sparse vegetation
Bare areas
A B
C
East Morocco
Habitat percentages [%]
0 20 40 60 80 100
Rainfed croplands
Mosaic croplands/Vegetation
Mosaic vegetation/Croplands
Mosaic Forest-Shrubland/Grassland
Closed to open shrubland
Sparse vegetation
Bare areas
availableused springused autumn
West Morocco
Habitat percentages [%]
0 20 40 60 80 100
availableused
44
Fig. 3.13: Ground truthing of Globcover digital land cover map (Globcover Source Data: ©
ESA / ESA Globcover Project, led by MEDIAS-France/Postel) with habitat types noted in prey
transect counts in East-Morocco 2010. Of each Globcover category, the sample size (number
of prey transect reference points) is given in brackets behind the category name.
Habitat selection: field data
Compositional analysis of habitat selection of all Montagu´s Harriers observed in
spring (n = 73) revealed that farmland was the only significantly preferred habitat
(Compositional analysis: λ = 0.041, p = 0.01, Fig. 3.14A). Harriers also used natural
steppe, Halfa steppe and Artemisia steppe, but to a lower proportion than available.
Villages and anti-erosion management areas were avoided. The same trend could
be shown in autumn, where Montagu´s Harriers (n = 11) preferred farmland
(Compositional analysis: λ = 0.002, p = 0.01, Fig. 3.14B). Like in spring, no harriers
were observed in villages and anti-erosion areas.
As there were not many observations during transect counts, these preferences
reflect mainly the choice of roosting habitat. Using all birds observed at roosts in
spring and autumn together (n = 60), Montagu´s Harriers preferred farmland
significantly (Compositional analysis: λ = 0.0001, p = 0.01, Fig. 3.15A). Except for
natural steppe, which was used for roosting to a lower proportion than available, all
other habitat types were avoided as roosts. If only individuals observed outside
roosts (n = 24) for both seasons combined were considered, farmland, natural
steppe, Artemisia steppe and Halfa steppe were significantly preferred, supposedly
0 5 10 15 20 25 30 35 40 45 80 100
rainfed croplands (2)
mosaic croplands/vegetation (8)
mosaic vegetation/croplands (4)
mosaic forest-shrubland/grassland (22)
closed to open shrubland (4)
sparse vegetation (145)
bare areas (1131)
anti-erosionArtemisia steppedepressionfarmlandHalfa stepperockssteppetreeswadi
45
representing preferred hunting habitats (Compositional analysis: λ = 0.0002, p =
0.01, Fig. 3.15B). Montagu´s Harriers also avoided anti-erosion areas and villages
during the day.
Using information on habitat degradation noted with Montagu´s Harrier observations
during road transect counts, it could be shown that harriers (n = 22) significantly
preferred habitats that were not degraded (Compositional analysis: λ = 0.010, p =
0.01, Fig. 3.16).
Fig. 3.14: Habitats used by Montagu´s Harriers observed during stopover in East-Morocco
2010 (used) compared to reference habitat types noted every 5 km during road transect
counts (available). A: spring, N = 73 birds. B: autumn, N = 11. Asterisks indicate preference
based on compositional analysis.
B
habitat percentages
0 20 40 60 80
A
habitat percentages
0 20 40 60 80
anti-erosion
farmland
natural steppe
Artemisia steppe
Halfa steppe
village
availableused
***
46
Fig. 3.15: A: Habitats used by Montagu´s Harriers (N = 60) at roosts in spring and autumn in
East-Morocco 2010 (used), compared to reference habitat types noted every 5 km during
road transect counts (available). B: Habitats used by Montagu´s Harriers (N = 24) outside
roosts in spring and autumn in East-Morocco 2010 (used), compared to reference habitat
types noted every 5 km during road transect counts (available).
Fig. 3.16: Proportion of Montagu´s Harriers observed in East-Morocco 2010 (n = 22) vs. the
proportion of different degradation categories (see 2.3) of habitats available during transect
counts (reference habitat noted every 5 km). Values above line through origin (f(x) = x)
indicate preference, values below the line avoidance.
A
habitat percentages
0 20 40 60 80 100
anti-erosion
farmland
natural steppe
Artemisia steppe
Halfa steppe
village B
habitat percentages
0 20 40 60 80 100
availableused
***
Proportion of degradation categories of habitat available [%]
0 10 20 30 40 50 60 70
Pro
port
ion
of M
onta
gu´s
Har
riers
obs
erve
d [%
]
0
10
20
30
40
50
60
70
no degradation
much degradation
few degradation
47
3.4 Prey abundance and prey choice
Prey abundance in East-Morocco
In total, 7141 potential prey birds, 88 reptiles and amphibians, 20 mammals, 3054
small mammal and reptile holes and 7410 insects were observed. In autumn, we
separated small mammal and reptile holes: 351 reptile holes were identified.
The Shannon-Weaver diversity index for potential prey bird species was 2.22
(N = 2932, 39 species) in spring and 2.09 (N = 2906, 26 species) in autumn; both
reflecting medium values of diversity. The evenness was 0.61 and 0.64, respectively,
showing that individuals of potential prey birds were not evenly distributed over
species.
This was also visible in the dominance structure (relative abundance of a species in
comparison to other species) of prey bird species in spring and autumn (Fig. 3.17
and Fig. 3.18). Most species were subrezedent (dominance <1 %, spring: 28
species, autumn: 17) or rezedent (1-2 %, spring: 2, autumn: 2). In spring, 3 species
were subdominant (2-5 %). In both seasons, 5 species were dominant (5-10 %).
Among those were in both cases Temminck´s Lark, Lesser Short-toed Lark, and
Barn Swallow. In spring, Short-toed Larks were by far the most abundant
(eudominant >10 %) species. The two most abundant species in autumn were
Calandra Lark and Short-toed Lark. In spring, most of the potential prey birds that we
observed were local breeding birds. Migrating songbirds were only observed
occasionally, not contributing a lot to potential prey bird abundance in East-Morocco.
In autumn, we observed big groups of larks, mainly Calandra Lark and Short-toed
Lark, which is also reflected in the dominance structure.
48
Fig. 3.17: Dominance structure of potential prey bird species observed during prey transect
counts in East-Morocco in spring 2010. N = 39 species. For scientific names see Appendix 5.
dominance
2 4 6 8 10 40
Brown-throated MartinHouse Martin
RedstartBlackbirdGoldfinch
Serin Whitethroat
Black WheatearMotacilla spec
Tawny PipitWood WarblerZitting Cisticola
Sand MartinThick-billed LarkHouse Sparrow
WhinchatBar-tailed Lark
Red-throated PipitSeebohm s Wheatear
Bee-eaterCorn Bunting
Willow WarblerDesert Wheatear
Red-rumped WheatearTrumpeter Finch
SkylarkNorthern Wheatear
Crested LarkHoopoe Lark
Yellow WagtailThekla Lark
Calandra LarkSpanish Sparrow
Lesser Short-toed LarkBarn Swallow
Temminck s LarkCommon Swift
Short-toed Lark
49
Fig. 3.18: Dominance structure of potential prey bird species observed during prey transect
counts in East-Morocco in autumn 2010. N = 26 species. For scientific names see Appendix
5.
Temporal and spatial variation in prey abundance
In spring, significantly more potential prey birds were observed during transect
counts than in autumn (GLM, F = 9.027, p = 0.003, Fig. 3.19B). During both
seasons, we counted more transects in the morning between 7:00 – 11:00 h (Fig.
3.19A). Highest numbers of birds in spring were observed in the early morning, with
decreasing numbers towards the hotter time of the day and again an increase in the
afternoon. The same was true in autumn, where highest numbers of birds were
counted between 7:00 – 9:00 h in the morning and 15:00 – 17:00 h in the afternoon.
The peak between 12:00 – 13:00 h in spring resulted from only five transects
counted in this hour, of which four were in more profitable habitats supporting
proportionally more birds. Nevertheless, the abundance of prey birds was not
significantly influenced by time (F = 1.840, p = 0.175). There was no variation of prey
bird abundance due to a varying frequency of transect kilometers counted over the
dominance
0 5 10 15 20 35
Rufous Bush RobinSand MartinWhitethroat
Tristram s WarblerScrub Warbler
Seebohm s WheatearChaffinch
Common SwiftGoldfinch
White-crowned WheatearDupont s Lark
Desert WheatearCrested Lark
Bar-tailed LarkThick-billed Lark
Desert LarkNorthern Wheatear
Hoopoe LarkRed-rumped Wheatear
Trumpeter FinchThekla Lark
Temminck s LarkBarn Swallow
Lesser Short-toed LarkCalandra Lark
Short-toed Lark
50
day (F = 1.579, p = 0.209). Unfortunately, transect length itself influenced the
number of potential prey birds counted (F = 114.823, p < 0.001).
Fig. 3.19: A: Total length of counted prey transects per hour of the day in spring and autumn.
B: Potential prey birds per kilometer transect over the hours of the day in spring and autumn.
Local time = UTC. Dark grey bars indicate approximately sunrise and sunset.
To evaluate the spatial differences in prey abundance during spring and autumn
stopover of Montagu´s Harriers in East-Morocco 2010, we divided the study area in
11 regions, which had specific habitat and landscape characteristics in common (see
Fig. 2.3, Table 5).
The Shannon-Weaver diversity index of bird species per region varied
between 0.64 in the wooded Bni Snassen mountains (area 2) and 2.32 in the rocky
steppe around Bouarfa and Mengoub (area 9; Table 5). All regions in steppe areas
on the high plateaus showed medium values around 2, indicating that the diversity is
not poor in these regions. The evenness ranged from 0.53 in the steppe around Ain
Benimathar and in the farmland close to Oujda (area 1 and 3) to 0.92 in the Bni
Snassen mountains (area 2). Most of the areas showed high values, indicating that
individuals were not even distributed among species. The abundance of potential
prey birds differed between the regions (GLM, F = 12.629, p = < 0.001). Most
potential prey birds were observed in regions dominated by steppe vegetation
(spring: area 1, 7 and 9; autumn: area 5, 1 and 9; Fig. 3.20). Highest densities of
B
hours of the day
06 07 08 09 10 11 12 13 14 15 16 17 18 19
pote
ntia
l pre
y bi
rds/
km
0
20
40
60
80
100A
hours of the day
06 07 08 09 10 11 12 13 14 15 16 17 18 19
tota
l tra
nsec
t len
gth
[km
]
0
10
20
30
40
50
springautumn
51
insects were also counted in steppe vegetation (spring: area 1 and 5; autumn: area 5
and 1). High numbers of insects refer mainly to beetles. Small mammal holes were
more abundant in autumn, e.g. in area 4, which had the highest number with 76
holes per transect-km in autumn, and 5 holes/transect-km in spring. Reptiles,
amphibians and small mammals were only observed occasionally.
Summing up, the regions on the high plateaus, dominated by steppe vegetation,
showed a high abundance of potential prey birds in both seasons. There are several
species that may be of importance as potential prey, but most notably was the
abundance of Short-toed Larks in both seasons. Satellite tagged Montagu´s Harriers
used mainly areas in regions with higher potential prey availability (area 1, 6, 7, 8; cf.
Fig. 3.4).
52
Table 5: Prey transects per area, area name and characteristics. Sum of birds observed and numbers of bird species per area, as well
as Shannon-Weaver Index (Hs) and Evenness (E) for each area, spring and autumn combined. Positions of areas see Fig. 2.3.
area name characteristics n transects length n birds n birds/km n species Hs E
1 Ain Benimathar high plateau, steppe 230 113.75 2841 24.98 45 2.01 0.53
2 Bni Snassen mountains, trees 2 0.82 3 3.66 2 0.64 0.92
3 Oujda farmland, crop 3 1.58 121 76.47 15 1.43 0.53
4 Jerada hills, steppe, trees 11 3.81 38 9.97 10 1.83 0.79
5 Taourirt steppe 51 17.75 640 36.06 18 1.59 0.77
6 Rekkam plateau high plateau, steppe 43 16.91 254 15.02 17 2.20 0.78
7 Maatarka high plateau, steppe 45 20.07 606 30.19 18 1.64 0.57
8 Tendrara high plateau, steppe 97 38.10 438 11.50 21 2.22 0.73
9 Bouarfa-Mengoub rocky steppe 122 55.58 978 17.60 35 2.32 0.65
10 Atlas mountains 38 16.91 54 3.19 13 2.21 0.82
11 Bouanane-Errachidia sandy, rocky 12 9.58 33 3.44 12 2.12 0.85
52
53
mean number per km0 5 10 15 20
mean number per km0 20 40 60 80
mean number per km0 10 20 30 40 50 60 70 80
prey birds
insects
mammal holes
reptiles/amphibians
mammals
mean number per km0 5 10 15 20
mean number per km0 2 4 6 8
mean number per km0 20 40 60 80 100
prey birds
insects
mammal holes
reptiles/amphibians
mammals springautumn
1 32
4 5 6
mean number per km0 2 4 6 8 10 12 14 16 18
prey birds
insects
mammal holes
reptiles/amphibians
mammals
mean number per km0 5 10 15 20 25
mean number per km0 5 10 15 20 25 30
prey birds
insects
mammal holes
reptiles/amphibians
mammals springautumn
mean number per km0 10 20 30 40 50
7 8
10 11
mean number per km0 5 10 15 20 25 30 35 40
9
Fig. 3.20: Mean number of prey categories per region. Note the different scales of the x-axes.
Positions of regions see Fig. 2.3.
54
Prey abundance in different habitats
Habitat type had a significant influence on the abundance of potential prey birds
(GLM, F = 10.888, p = 0.002). In spring, highest numbers of potential prey birds per
kilometer transect were observed in farmland and depressions (Fig. 3.21A). The
abundance was also high in natural steppe, Halfa steppe and Artemisia steppe,
containing more than 20 birds/km. Fewer prey birds were counted in anti-erosion,
wooded and rocky areas. The number of insects, mostly beetles, in spring was
highest in the steppe habitats. The very high number of more than 160 insects/km in
Artemisia steppe was strongly influenced by counts in one area with many beetles.
In autumn, most birds/km transect were observed in farmland and Artemisia steppe
(Fig. 3.21B). Relatively high densities of potential prey birds were also counted in
natural steppe, Halfa steppe and close to wadis, where often small puddles of water
were available. Lowest counts in autumn were in depressions and anti-erosion
areas. Insects were most abundant in steppe habitats, as they had been in spring.
Small mammal holes were more numerous in farmland and depressions in autumn
than in spring.
The number of potential prey birds decreased in more degraded habitats (F = 4.040,
p = 0.007; Fig. 3.22). The same could be seen for the number of observed small
mammal holes and of insects in autumn (Fig. 3.22B). Only the number of insects in
spring was higher in more degraded areas than in areas that were less degraded
(Fig. 3.22A).
Satellite tagged Montagu´s Harriers preferred farmland and steppe habitats for
hunting (cf. 3.3, Fig. 3.15). Combining these results, harriers chose hunting habitats
with higher availability of potential prey birds. They also avoided heavily degraded
habitats which contain less potential prey (cf. 3.3, Fig. 3.16).
55
Fig. 3.21: Number of potential prey/km prey transect counted, in the different habitat types
during spring (A) and autumn (B) 2010. Note the different scales.
Fig. 3.22: Number of potential prey/km prey transect counted, in the different degradation
categories in spring (A) and autumn (B) 2010. Categories see 2.3. Note the different scales.
Prey choice during spring stopover
All pellets originated from a roost at a farm south of Ain Benimathar, used by
approximately 10 Montagu´s and 10 Marsh Harriers on 17 and 22 April 2010.
Analyzing 21 pellets of Montagu´s Harriers (114 prey items were identified) revealed
that the main prey were passerine eggs and birds, small mammals and reptiles (Fig.
3.23).
A
number/km
0 10 20 30 40 50 60 175
anti-erosion
depression
farmland
natural steppe
Artemisia steppe
Halfa steppe
rocks
trees prey birdsinsectsmammal holesreptiles
B
number/km
0 10 20 30 40 50
anti-erosion
depression
farmland
natural steppe
Artemisia steppe
Halfa steppe
wadi
A
degradation
0 1 2 3
num
ber/
km
0
20
40
60
80
prey birdsinsectsmammal holesreptiles
B
degradation
0 1 2 3
num
ber/
km
0
5
10
15
20
25
30
56
Egg shell remains made up nearly half of the average volume and weight of the
pellets (Fig. 3.23A). Also important proportions of bones, feathers, reptile scales,
beetles and mammal hair were found. The proportions of prey items according to
estimated volume in pellets and the weighed proportion in pellets did not differ
significantly (Fisher´s Exact Test, p = 0.815).
Referring to minimal numbers of prey categories, small prey items like
beetles and eggs made up 81 % of total numbers (Fig. 3.23B). Concerning biomass,
however, birds and eggs made up 81 %, small mammals accounted for 11 %,
reptiles and beetles added only little (Fig. 3.23B). The average proportion of prey
items based on the number counted in pellets and estimated biomass of the
categories did differ significantly (Fisher´s Exact Test, p < 0.001).
Fig. 3.23: A: Average proportion of mean estimated volume in pellets and weight of different
pellet fractions separated according to different prey categories. B: Average proportion of
(minimum) number and estimated fresh biomass of different prey categories in pellets. n = 21
pellets found at a roost south of Ain Benimathar, Morocco (used by 10 individuals) on 17 and
22 April 2010.
B
number biomass
aver
age
prop
ortio
n in
die
t [%
]
0
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eggsbeetlesbirdsreptilesmammals
A
volume weight
aver
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ortio
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]
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egg shellsbonesfeathersreptile scalesbeetlesmammal hairplant material
57
4. Discussion
Importance of Montagu’s Harriers’ stopover sites in West- and East-Morocco
revealed by satellite telemetry
Satellite telemetry proved to be a useful tool to analyze stopover behavior of
Montagu´s Harriers. Around ¾ of northwest-European satellite-tagged Montagu’s
Harriers reached their wintering and breeding areas, on a route via Spain (see 1.).
The “Spanish” route is thereby one of the most important migratory pathways for
Montagu’s Harriers in the Western Palaearctic (Trierweiler & Bijlsma in prep.,
Trierweiler 2010). Here, we show that on average more than half of Montagu’s
Harriers using this pathway stopped over in Morocco, with almost 80 % of individuals
in spring and around 40 % in autumn.
Supposing that the proportions of satellite-tagged Montagu’s Harriers using
the stopover site are representative for the whole western European Montagu’s
Harrier breeding populations (including southern European ones), we can conclude
that more than 8,500 breeding pairs or 28,000 individuals of the total 11,500
breeding pairs (36,800 individuals) migrating on this pathway may use Morocco as
stopover site (Trierweiler & Bijlsma in prep., Trierweiler 2010, this study). Morocco
may, however, be more important as stopover site for Montagu’s Harriers from
northern Europe that migrate approximately 5000 km, than for southern European
birds that migrate only around 2500 km to their wintering areas. Actual numbers of
Montagu’s Harriers stopping over may therefore be much lower than the above
estimate, taking into account that the Spanish Montagu’s Harrier population is the
largest in western Europe (Mebs & Schmidt 2006, Trierweiler & Bijlsma in prep.).
Differential use of the stopover area Morocco during autumn and spring migrations
The higher importance of Morocco as stopover site in spring than in autumn could be
explained by e.g. the possibilities of refueling in Europe during autumn migration,
compared to arrival in Morocco after the Sahara desert crossing in spring. In autumn,
prey may be widely available on the migration through Europe: populations of small
mammals in Europe may reach their highest numbers during the annual cycle in
autumn (Dijkstra et al. 1995). In spring, however, Montagu’s Harriers leave the
Sahelian wintering quarters at the end of the dry season, when food sources are
probably at their lowest level during the annual cycle, and they cross the desert,
which may be food-deprived on wide stretches. The harriers, potentially facing
58
energetic bottlenecks, may then encounter the first possible stopover area in
Morocco. Several other potential reasons for the higher importance of Morocco
during spring migration may be thought of. For instance, differences in weather
circumstances may influence migration and stopover dynamics in Montagu’s
Harriers. Also, the exceptionally high food abundance in (East-)Morocco in spring
may be very attractive for Montagu’s Harriers, whereas food abundance in (East-
)Morocco is much lower in autumn and may thereby be not especially attractive
compared to stopover sites in Europe. Independent of the number of potential prey
birds the chance to catch an individual bird must be higher in spring e.g. incubating
females on nests, than in autumn when larks were often seen in big groups. Another
aspect leading to stopover may be a social component. Montagu´s Harriers were
found to use communal roosts during stopover in East-Morocco. Further studies are
needed to investigate the differential importance of Morocco during spring and
autumn migration, and the attractiveness of Morocco compared to European areas
as stopover site for Montagu’s Harriers.
Stopover phenology and site faithfulness
On average, satellite-tagged northwest-European Montagu´s Harriers stopped over
in Morocco for 9 days, in spring arriving around 12 April, in autumn around 17
September. It could have been expected that Montagu´s Harriers stop over for fewer
days in spring, because their migration is shorter in spring than in autumn
(Trierweiler 2010). However, the duration of stopover did not differ between the
seasons. Maybe birds make less stopover days in other areas in spring or migrate
slower in autumn. For several birds that were tracked in subsequent years, site
faithfulness to the stopover areas in Morocco could be shown. The satellite-tagged
Dutch adult male Franz for example always used the same stopover area in East-
Morocco during spring migration (except for one spring, when he did not stop over,
2007 - 2010). Danish adult female Mathilde was the only satellite-tagged harrier of
whom we documented the use of the western Moroccan stopover area in spring and
the eastern area in autumn (2009 - 2010). Strong site fidelity to East-Morocco during
stopover could also be shown for Dutch/German adult female Merel, who returned to
her Moroccan stopover area in six seasons (spring and autumn 2006 - 2009). This
bird also showed a strong site fidelity in the wintering grounds where she visited the
same home ranges in three consecutive years (Trierweiler 2010). The high site
59
faithfulness to the stopover site indicates a high degree of migratory connectivity
between breeding, stopover and wintering populations of Montagu’s Harriers. This
connectivity may cause carry-over effects of ecological conditions during stopovers
in Morocco to subsequent seasons (e.g. wintering, breeding). The existence of such
carry-over effects for Montagu’s Harriers should be investigated in future studies.
Distribution and abundance of Montagu´s Harriers in East-Morocco
East-Morocco has not received much attention in ornithological studies as yet. It is a
region with little infrastructure, which is neither visited by many tourists nor the
destination of many scientific expeditions. The lack of observations of Montagu´s
Harriers in this region reported in ornithological literature is clearly an effect of the
absence of observers, and not of the absence of birds (Thevenot et al. 2003, cf. this
study). Additionally, field observations are dependent on i) chance, ii) length and
intensity of transect counts, iii) number of times passing through the same areas
during road transect counts. This highlights the importance of satellite telemetry
studies that are able to discover and identify areas of ecological importance for birds,
also in the absence of local observers or previous reports from the field.
During road transect counts the detection probability of birds is generally dependent
on the distance from the road as well as on the size of the bird. I have shown that the
detection of raptors during Moroccan road transects decreased after 100 m and that
92 % of observations lay within 400 m. Future analysis should incorporate
calculations of the detection probabilities of different bird species, taking into account
their size and behavior. This could be conducted if more observations were
available. That no significant day-time variation in the number of raptors counted was
found, could also be biased by the low sample size. Other studies reported that
during road transect counts raptor observations were influenced by time of day
(Thiollay 2006).
Of the total raptor density of 5.3 raptors per 100 km road transect in East-
Morocco during migration periods, 0.2 per 100 km road transect were Montagu´s
Harriers. The resolution of these road transects may have been too low to find
significant differences between autumn and spring numbers, which have been
identified in the satellite telemetry data. In the wintering areas, higher road counts of
Montagu’s Harriers have been reported: 0.43 and 0.52 Montagu´s Harriers per 100
60
km in Niger in 2006 and 2007 (Trierweiler & Koks 2009) and 0.7 to 0.9 in the western
Sahel 2003-2004 (Thiollay 2006). These differences in densities may be a result of
the temporal and spatial patterns of use of the area. Montagu’s Harriers travel
through Morocco on a relatively wide front and in a relatively wide time window of
about four weeks. In the Sahel, on the other hand, wintering harriers spend several
months in restricted areas and show strong fidelity to wintering home ranges
(Trierweiler 2010).
Apart from road transects, observing Montagu’s Harriers in the wintering
areas may not be as difficult as in the stopover site, because of the higher
detectability of great numbers of harriers, which accumulate in communal roosts
(Trierweiler & Koks 2009). In Morocco, detecting (small) roosts or even individual
harriers proved very difficult without tracking satellite tagged harriers.
Habitat selection of Montagu’s Harriers during stopover in Morocco
Based on analyses of Montagu’s Harrier satellite telemetry data together with a
digital land cover map (Globcover), we conclude that harriers chose their stopover
sites not randomly within the reference area, which comprised parts of Morocco and
Algeria and was dominated by ‘bare areas’. In the western Moroccan stopover area,
harriers selected different agricultural habitat types, whereas in the eastern area,
they preferred ‘bare areas’. According to the digital map, the whole west of Morocco
was dominated by agricultural fields in contrast to the east, which was dominated by
‘bare areas’. This explains why habitat selection was not significant when based on
habitat abundance within smaller, western and eastern reference areas, respectively.
The harriers’ preference for either agricultural habitat types (located in the west) or
‘bare areas’ (in the east) seems to be inherent in their migratory route choice through
either West- or East-Morocco.
The ecological significance of ‘bare areas’ as harrier habitats was surprising.
However, ground truthing of the Globcover land cover categories by habitat
categories noted in the field in East-Morocco revealed that ‘bare areas’ were
composed of multiple habitat types, 71 % of these being steppe habitats and 12 %
farmland. The ground truthing thus shows the limited usefulness of the Globcover
land cover map. Classifying the eastern Moroccan steppe as ‘bare areas’ by
Globcover (based on satellite scenes) may relate to how open and sparsely
vegetated this steppe is. In the light of ground truthing, our results most probably
61
indicate a preference of the harriers for mainly natural steppe habitats in East-
Morocco. The classification of habitat types in the field could also cause bias, but
was always conducted in the same way to reduce this.
Montagu´s Harriers observed in East-Morocco preferred farmland habitats.
This preference was mainly based on the use of these habitats for roosting. For
hunting, the restricted number of observations indicated that steppe habitats were
more important than farmland habitats. These direct observations clarify the
conclusions from the telemetry/remote sensing data and additionally revealed that
harriers prefer non-degraded over degraded habitats. The latter indicates the
importance of conservation actions to counteract degradation of steppe and farmland
habitats in East-Morocco.
The differential use of the western and eastern stopover site, with the
western site being used mostly in spring and less in autumn (in contrast to the
eastern site being used in both seasons), may be related to the different habitat
types (agricultural vs. natural) dominating these areas.
Additional to the low accuracy of the Globcover land cover map, another
factor limiting inference from digital maps on habitat use of satellite tracked birds is
the low precision or inaccuracy of satellite fixes. Future analyses will make use of
very accurate and much more precise data from GPS loggers mounted on
Montagu’s Harriers. These data allow also a much higher temporal resolution.
Because of the drawbacks of current telemetry and remote sensing data
analyses, traditional fieldwork was not only important for ground truthing but also for
direct observations of habitat preferences of Montagu’s Harriers.
Prey abundance and prey choice
The availability of potential prey birds was highest in regions that were also used by
satellite tagged Montagu´s Harriers. Mainly the steppe on the high plateaus was
holding great amounts of potential prey. We could show that Montagu´s Harriers
chose those habitat types that were rich in potential prey for hunting. Poorer habitat
types and degraded habitats were avoided by the observed harriers.
The diet of Montagu’s Harriers during stopover in East-Morocco was dominated by
resident songbirds. Pellet analysis revealed that songbirds, their eggs and nestlings
were the most important prey items, accounting for approximately 67 % of fresh
(wet) biomass eaten. The main food source of Montagu´s Harriers in the breeding
62
area in the Netherlands is the Common Vole (Microtus arvalis; Koks et al. 2007).
Other common prey items are songbirds like Sky Lark (Alauda arvensis), Meadow
Pipit (Anthus pratensis) and Yellow Wagtail (Motacilla flava; Koks et al. 2007).
Harriers around Madrid feed on lagomorphs and lots of other prey types during the
breeding season (Arroyo 1997). At the wintering sites the main prey is non-migratory
grasshoppers (Trierweiler et al. 2008).
Keeping in mind that during the wintering period grasshoppers and locusts
are the most important prey items, we expected Montagu´s Harriers to feed on them
in Morocco, too. However, during our field expeditions, we observed grasshoppers
only occasionally. Arroyo (1997) named the Montagu´s Harrier an “opportunistic
specialist”, specializing on the best available and catchable food. This seems to hold
true also for prey choice during stopover, where mainly songbirds were eaten, but
also reptiles, mammals and insects were common prey items.
Threats for Montagu´s Harriers in East-Morocco and conservation and management
implications
The main threats for the local biodiversity in Morocco are human population growth
and resulting processes as deforestation and overgrazing:
“Population growth, the exponential demand on agricultural lands, together
with the collective status of land expanses, have resulted in deforestation
and appropriation of lands to cultivate cereals. The loss [of land] is
believed to be roughly 65 000 hectares[.] 3 to 5 times the recommended
animal charge [put additional pressure on the landscape].”
The National Environment Observatory of Morocco
Additionally, ecological changes because of missing rainfalls during winter are
accelerating degradation. Those changes not only have impacts on local breeding
birds, but can also influence or threaten long-distance migrants like the Montagu´s
Harrier. As predators raptors are dependent on a well functioning food chain.
Changing conditions that influence populations of prey animals like songbirds,
reptiles, small mammals and big insects also have an effect on their predators.
In the field, bullet casings were only encountered in a small number of cases.
In autumn, we observed a hunting party, searching a reserve west of Bouarfa,
63
probably to hunt Houbara Bustards (Chlamydotis undulata). Only one shot Stone
Curlew (Burhinus oedicnemus) was found in autumn. No other hints of illegal
persecution or hunting of Montagu’s Harriers or other bird species were encountered
during our field trips. This is consistent with the statements of local foresters and
birders who judged illegal hunting to be scarce or absent in East-Morocco.
During our field trips to East-Morocco, we could identify some factors that
may represent hazards to Montagu´s Harriers during stopovers. The encountered
ecosystems harbor habitat types, like steppe and extensive farmland that provide
most prey for Montagu’s Harriers. We show here that degradation lowers food
abundance and therefore could make circumstances for harriers on stopover less
favorable. Although seemingly remote and poor compared with other systems, the
steppe ecosystem is unique extending only over eastern Morocco and western
Algeria. Taking account of the results presented above, this region should
experience further conservation efforts in the future.
64
5. Summary
The Montagu´s Harrier (Circus pygargus) is a long-distant migratory raptor breeding
in the western Palaearctic and wintering south of the Sahara desert. Analyzing
satellite telemetry data of Montagu´s Harriers that migrated on a western route via
Spain revealed that during autumn migration, 41 % of tagged individuals used
stopover sites in Morocco. During spring migration, Morocco was even of greater
importance with 76 % of tracked Montagu´s Harriers stopping over. Analyses
revealed two major stopover areas in Morocco. One in western and one in eastern
Morocco, with the latter one being of greater importance because it was used by
more individuals and during spring as well as autumn migration. Satellite tagged
Montagu´s Harriers made on average 9-day stopovers in Morocco during spring and
autumn migration. Individuals that could be followed in consecutive years showed
site fidelity to the stopover areas in Morocco. During two field expeditions in East-
Morocco 2010, we observed Montagu´s Harriers during stopover, counted all raptors
during road transects, collected data on prey abundance by walking prey transects,
and gained insight in food choice by collecting pellets at communal roosts. In spring,
73 Montagu´s Harriers were observed, in autumn 11. Communal roosts discovered
in both seasons were used by Marsh and Montagu´s Harriers with about 10
individuals of each species. During road transect counts, the overall number of
raptors per 100 kilometer road transect was 5.3. Per 100 km transect, 0.1 Montagu´s
Harriers were observed in spring and 0.3 in autumn. Using a digital global land cover
map (Globcover), in comparison to Morocco as reference area the stopover sites of
Montagu´s Harriers were not chosen randomly in respect of habitat. In the eastern
stopover area, in spring and autumn, the land cover category ‘bare areas’ was
overrepresented compared to the reference area. In the western spring stopover
area, vegetation categories depicting farmland were overrepresented compared to
the reference area. However, ground truthing with prey transect habitat categories
revealed that the Globcover land cover categories were often different from the
habitat type noted in the field with ‘bare areas’ being reflected by steppe vegetation
and farmland in East-Morocco. Observed Montagu´s Harriers preferred farmland at
roosts. During the day, farmland, natural steppe, Artemisia steppe and Halfa steppe
were preferred, supposedly representing preferred hunting habitats. Montagu´s
Harrier observed in the field preferred habitats that were not degraded. The
availability of potential prey birds was highest in regions on the high plateaus. These
65
were the areas used by tagged Montagu´s Harriers during stopover. Most abundant
potential prey birds among others were Short-toed Larks that were encountered in
very high numbers during both seasons. In spring, more potential prey birds were
counted than in autumn. During spring stopover, breeding birds, their nests and
young seem to provide potential prey. Pellet analysis revealed that the main prey in
spring were passerine eggs and birds, small mammals and reptiles. In spring,
highest numbers of potential prey birds per kilometer transect were observed in
farmland and depressions. The abundance was also high in natural steppe, Halfa
steppe and Artemisia steppe, containing more than 20 birds/km. In autumn, most
birds/km transect were observed in farmland and Artemisia steppe, but also big
groups of larks, mainly Calandra Lark and Short-toed Lark, were observed outside
transects. The number of potential prey birds decreased in more degraded habitats.
Satellite tagged Montagu´s Harriers preferred farmland and steppe habitats
for hunting and therefore chose hunting habitats with higher abundances of potential
prey birds. They also avoided heavily degraded habitats which contained less
potential prey. The findings of the first field expeditions combined with analyses of
satellite telemetry data show that the steppes on the high plateaus of East-Morocco
are of great importance for Montagu´s Harriers during stopover in spring as well as in
autumn. Efforts should be made to preserve this unique landscape for long-distance
migrants using it as stopover site as well as for local breeding birds.
66
6. Zusammenfassung
Die Wiesenweihe (Circus pygargus) ist ein Langstreckenzieher, der in der westlichen
Palaearktis brütet und südlich der Sahara überwintert. Die Analyse von
satellitentelemetrischen Daten von Wiesenweihen, die über Spanien in ihre
Winterquartiere ziehen, ergab, dass während des Herbstzuges 41 % der
besenderten Wiesenweihen eine Rast in Marokko einlegten. Während des
Frühjahrszuges war Marokko von noch größerer Bedeutung, dort rasteten 76 % der
mit Sendern versehenen Wiesenweihen. Die Analysen zeigen zwei bedeutende
Rastgebiete in Marokko: eines im Westen, das andere im Osten des Landes.
Letzteres war von größerer Bedeutung, da es von mehr Individuen und sowohl
während des Frühjahrs- als auch des Herbstzuges genutzt wurde. Besenderte
Wiesenweihen rasteten in Marokko durchschnittlich 9 Tage. Individuen, die über
mehrere Jahre verfolgt werden konnten, zeigten Ortstreue in den Rastgebieten in
Marokko. Während zweier Feldexpeditionen nach Ost-Marokko 2010 beobachteten
wir Wiesenweihen während der Rast, zählten alle Greifvögel mit Hilfe von
Straßentransektzählungen, sammelten Daten zur Beuteverfügbarkeit mit Hilfe von
Beutetransektzählungen und gewannen einen ersten Eindruck in die
Nahrungszusammensetzung von Wiesenweihen anhand von Gewöllen, die bei
gemeinsamen Schlafplätzen gefunden wurden. Im Frühjahr wurden 73
Wiesenweihen beobachtet, im Herbst 11. Gemeinsame Schlafplätze, die während
der beiden Expeditionen gefunden wurden, wurden von Rohr- und Wiesenweihen,
jeweils rund 10 Individuen, gemeinsam genutzt. Während der
Straßentransektzählungen war die Anzahl der Greifvögel 5,3 pro 100 km Transekt.
0,1 und 0,3 Wiesenweihen pro 100 km wurden jeweils im Frühjahr und Herbst
gezählt. Betrachtet man eine digitale Landnutzungskarte (Globcover), so war die
Habitatzusammensetzung der Rastgebiete der Wiesenweihen verglichen mit
Marokko als Referenzgebiet, nicht willkürlich. Im östlichen Rastgebiet war sowohl im
Frühjahr als auch im Herbst die Landnutzungskategorie ‚kahle Gebiete‘ im Vergleich
zum Referenzgebiet überrepräsentiert. Im westlichen Rastgebiet waren im Frühjahr
Landnutzungskategorien, die landwirtschaftliche Nutzflächen wiederspiegeln, im
Vergleich zum Referenzgebiet überrepräsentiert. Ein Vergleich der
Landnutzungskategorien der digitalen Karte mit Habitatkategorien, die während der
Beutetransektzählungen notiert wurden, ein sogenanntes ‚Ground truthing‘, zeigte
jedoch, dass die Landnutzungskategorien oft nicht mit der Wirklichkeit
67
übereinstimmten. ‚Kahle Gebiete‘ waren in Ost-Marokko meist Steppen oder gar
landwirtschaftliche Nutzflächen. Die von uns beobachteten Wiesenweihen
bevorzugten landwirtschaftliche Nutzflächen als Schlafplatz. Während des Tages,
wahrscheinlich zur Jagd, bevorzugten sie landwirtschaftliche Nutzflächen und
Steppen aller Art. Die beobachteten Wiesenweihen bevorzugten Habitate, die nicht
degradiert waren. Die Verfügbarkeit von potentiellen Beutevögeln war in Regionen
mit hohen Plateaus am höchsten. Diese Gebiete wurden auch von den besenderten
Wiesenweihen zur Rast genutzt. Die häufigsten potentiellen Beutevögel waren
Kurzzehenlerchen, die wir sowohl im Frühjahr als auch im Herbst in großen
Anzahlen antrafen. Im Frühjahr wurden insgesamt mehr potentielle Beutevögel
gezählt als im Herbst. Während der Rast im Frühjahr scheinen Brutvögel, sowie
deren Eier und Junge potentielle Nahrungsquellen zu sein. Die Analyse von
Gewöllen, die während der Expedition im Frühjahr gesammelt wurden, zeigte, dass
die Hauptnahrung Singvogeleier und Singvögel, sowie Kleinsäuger und Reptilien
waren. Im Frühjahr wurde die höchste Dichte an potentiellen Beutevögeln in
landwirtschaftlichen Nutzflächen und Senken gefunden. Auch in verschiedenen
Steppenhabitaten waren mehr als 20 Vögel pro km Transekt zu finden. Im Herbst
wurden die höchsten Anzahlen an Beutevögeln pro km Transekt in
landwirtschaftlichen Nutzflächen und Artemisia Steppe gezählt. Auch beobachteten
wir große Gruppen von Kalanderlerchen und Kurzzehenlerchen außerhalb der
Transektzählungen. Die Anzahl der potentiellen Beutevögel war geringer in stärker
degradierten Habitaten.
Besenderte Wiesenweihen bevorzugten in Ost-Marokko landwirtschaftliche
Nutzflächen und Steppen als Jagdhabitat. Damit wählten sie während der Rast
Habitate mit hoher potentieller Nahrungsverfügbarkeit. Desweiteren vermieden
Wiesenweihen degradierte Habitate, die auch weniger potentielle Beute
beinhalteten. Die Auswertung der während der ersten beiden Expeditionen nach
Ost-Marokko gesammelten Daten zeigt, zusammen mit den satellitentelemetrischen
Daten, dass die Steppen auf den hohen Plateaus in Ost-Marokko von großer
Bedeutung für rastende Wiesenweihen sowohl während des Frühjahrs- als auch
während des Herbstzuges sind. Diese einzigartige Landschaft ist es wert, zukünftig
für Langstreckenzieher, die sie als Rastgebiet nutzen, und für lokale Brutvögel
erhalten zu werden.
68
7. Samenvatting
Grauwe Kiekendieven (Circus pygargus) zijn roofvogels die in Europa broeden en
zuidelijk van de woestijn in Afrika van de Sahel overwinteren. Analyses van
satellietzender data van Grauwe Kiekendieven, die via Spanje naar Afrika vliegen,
laten zien dat tijdens het najaarstrekmigratie 41 % van de gezenderde vogels een
stop maakte in Marokko. Tijdens de voorjaarstrek was Marokko van nog grotere
betekenis, omdat dan 76 % van de gezenderde Grauwe Kiekendieven daar een tijdje
hun trek onderbreken De analyses geven twee belanrijke pleisterplaatsen in
Marokko aan. Een in het westen de andere in het oosten van Marokko, de laaste is
van meer betekenis omdat daar meer individuen tijdens beide trekseisoenen zowel
voorjaars- als najaarsmigratie gebruik van maken. Gezenderde Grauwe
Kiekendieven pauzeren gemiddeld 9 dagen in Marokko tijdens de voor- en de
najaarstrek. Bij individuele vogels kon worden aangetoond dat zowel tijdens de
voorjaars- als de najaarsmigratie er plaatstrouw was aan pleisterplaatsen. Tijdens de
tweetal veldexpedities in Oost-Marokko in 2010 (april en september) hebben wij
geprobeerd gegevens over dichtheden, prooiaanbod en dieetkeuze van Grauwe
Kiekendieven te verzamelen. Hierbij werden systematische roofvogeltellingen vanaf
de weg uitgevoerd, het prooiaanbod geteld door transecten af te lopen en waar
mogelijk braakballen verzameld op slaapplaatsen. In het voorjaar hebben we 73
Grauwe Kiekendieven gezien, in het najaar 11. Op de gevondenen slaapplaatsen
zijn rond 10 Grauwe en 10 Bruine Kiekendieven waargenomen en braakballen
verzameld. Tijdens de wegtransecttellingen bedroeg het aantal roofvogels per 100
km transect 5,3, roofvogels. Het aantal Grauwe Kiekendieven bedroeg in het
voorjaar 0,2 en in het najaar 0,3 individuen per 100 km. Als je, een digitaale
landgebruik kaart gebruikend, de habitaten van de pleisteplaatsen van Grauwe
Kiekendieven met Marokko als referentie vergelijkt, dan lijken deze niet toevallig
gekozen te zijn. Bij analyse van de gegevens blijkt dat zowel tijdens de voorjaars- als
de najaarstrek het aandeel open gebieden significant te zijn oververtegenwoordigd in
de steekproef ten opzichte van de referentiegebieden In het oostelijke gebied was in
het voor- en najaar de landgebruik categorie 'kaale gebieden' oververtegenwoordigd
in vergelijk met het referentie gebied. In het westelijke voorjaars gebied waren
landgebruik categorieen, die agrarische gebieden betekenen, oververtegenwoordigd
in vergelijk met het referentie gebied. Maar als je dus de habitaten, die wij tijdens de
prooitransect tellingen noteerden, met de landgebruik categorien vergelijkd, is te zien
69
dat deze niet altijd juist zijn. 'Kaale gebieden' bijvoorbeeld zijn in het veld in Oost-
Marokko meestal steppe vegetatie of agrarische gebieden. Tijdens de
prooiaanbodtellingen bleek echter al snel dat de categorieën die worden gebruikt op
de satellietkaarten op onderdelen afweken van wat wij in het veld zagen. 'Open
gebieden' zijn in Oost-Marokko doorgaans gebieden met een karakteristieke
steppevegetatie of agrarisch gebied. In april bleken dus steppes en agrarische
gebieden met een zekere mate van akkerbouw te worden geprefereerd in
vergelijking tot de referentiegebieden. De Grauwe Kiekendieven, die we
observeerden, hadden een voorkeur voor agrarische gebieden als slaapplaatsen.
Tijdens de dag, hadden de kiekendieven een voorkeur voor agrarische gebieden en
verschillende typen steppe, dit representeerd waarschijnlijk foeragergebieden. De
steppegebieden zijn hoogstwaarschijnlijk preferent als foerageergebied Grauwe
Kiekendieven hadden een voorkeur voor gebieden die niet gedegradeerd waren. De
beschikbaarheid van potentiele prooi vogels was het hoogst in regios op de hogere
plateaus. Dit zijn ook tevens de gebieden die door de gezenderde Grauwe
Kiekendieven tijdens de rust als slaapplaats gebruikt worden. De prooisoort die in
beiden seisoenen met de hoogste aantallen te vinden was, is de Kortteenleeuwerik.
In het voorjaar worden meer potentieele prooi vogels getellt dan in het najaar.
Tijdens de voorjaarsrust lijken broedvogels, hun eieren en hun jongen als prooi
belangrijk te zijn. Dit bleek uit de verzamelde dieetgegevens. In april 2010 bleken
achtereenvolgens zangvogeleieren, nestjonge zangvogels, kleine zoogdieren en
tenslotte reptielen te worden geconsumeerd. In het voorjaar werd het hoogste
aandeel potentiële vogelprooien per km transect in agrarische gebieden en
depressies vastgesteld. De aantallen waren ook hoog in de verschillende typen
steppen habitatens met meer dan 20 vogels per km. In de herfst zijn de hoogste
aantallen zangvogels per km transect ook in agrarische gebieden en in Artemisia
steppe vastgesteld. Bovendien hebben we in het najaar grote groepen van
Kalanderleeuweriken en Korteenleeuweriken waargenomen. De dichtheden van
potentiële prooivogels bleek lager in h habitattypen die meer gedegradeert waren.
Gezenderde Grauwe Kiekendieven hadden een voorkeur voor agrarische
gebieden en steppen habitaten om te foerageren en kozen daarvoor habitaten waar
meer potentiële prooi vogels zaten. Zij vermeden ook erg gedegradeerde
landschappen als gevolg van het lagere prooiaanbod. Uit de resultaten van dit
onderzoek blijkt de combinatie van satellietzenderdata in combinatie met metingen in
70
het veld tot interessante conclusies te leiden. Uit de satellietdata bleek al dat Oost-
Marokko van grote betekenis was voor Grauwe Kiekendieven uit NW-Europa. Door
de expedities in april en september weten we nu ook dat niet gedegradeerde
agrarische en steppegebieden met hoge dichtheden aan leeuweriken worden
geprefereerd. Behoud van deze gebieden is dus van betekenis voor een trekvogel
als de Grauwe Kiekendief.
71
8. Acknowledgements
Field work was carried out together with Christiane Trierweiler, Ben Koks and Rob
Buiter in spring 2010. Data was collected together with CT, BK and Hans Hut in
autumn 2010. For great support with the analyses and revision of the text, I warmly
thank CT. Thanks to Arne Hegemann for help with statistical analyses and all
persons reviewing former versions of the text. Jesús García helped us with his
advice. The Institute of Avian Research “Vogelwarte Helgoland” provided me with a
working environment in Wilhelmshaven throughout the analyses. I am grateful to the
Dutch Montagu´s Harrier Foundation that supported and taught me during the field
season. The project was financially possible due to support of the Deutsche
Wildtierstiftung (grant to CT), the DAAD (grant to AS), the Dutch Montagu’s Harrier
Foundation (who provided the satellite telemetry data and funding for fieldwork), the
Schure-Beijerink Popping Fonds and the Dr. J.L. Dobberke Stichting (both providing
funding for fieldwork). The work in Morocco was kindly facilitated by the local
counterparts Dr. Hamid Rguibi (University of El Jadida) and Khalid Bedhiaf
(president of the East-Moroccan Bird Ligue). The Ministry of Eaux & Forêts provided
a license to carry out scientific work in Morocco. The local forestries of Eaux &
Forêts and the local police stations provided support in the field. We are very grateful
for the great hospitality of the members of the East-Moroccan Bird Ligue.
72
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10. Appendix
Appendix 1: PTT ID, name, catching place, country, location and date, age and sex of 20 satellite tracked Montagu´s Harriers, of which data was
used in the analyses sorted by catching date. Catching location is given in decimal degrees. Age is at catching time. Exact age was known for
nestlings and birds ringed as nestlings. Females with brown iris coloration were aged as being approximately 3-4 K (calendar year). Sex “f” =
female, “m” = male.
catching location PTT ID name place country N E catching date age sex
67278 Rudi E-Groningen NL 53.21 7.1 15-Jul-06 adult m
41249 Cathryn E-Groningen NL 53.15 6.95 15-Jul-06 adult f
67277 Franz E-Groningen NL 53.11 7.13 20-Jul-06 6K m
66841 Merel N-Groningen NL 53.41 6.45 24-Jul-06 adult f
67275 Freyr Leer D 53.17 7.21 28-Jul-06 adult m
41434 Jinthe Flevoland NL 52.38 5.33 3-Jul-07 7K f
41170 Sigrid Flevoland NL 52.38 5.33 14-Jul-07 1K f
41325 Doris Soest D 51.62 8.44 17-Jul-07 adult f
41303 Margret Soest D 51.63 8.44 21-Jul-07 14K f
41202 Edzard E-Groningen NL 53.22 6.91 1-Aug-07 4K m
41311 Fenna E-Groningen NL 53.22 6.91 1-Aug-07 adult (3-4 K?) f
66842 Tania Hrodna BY 53.31 23.93 13-Jul-08 adult (3-4 K?) f
84627 Jurek Siedlce PL 52.1 22.85 16-Jul-08 1K m
84629 Jochen Cuxhaven D 53.79 8.56 26-Jul-08 3K m
94497 Remt N-Groningen NL 53.41 6.45 13-Jul-09 adult m
84625 Iben Ballum DK 55.09 8.67 18-Jul-09 2K f
94494 Mathilde Ballum DK 55.09 8.67 18-Jul-09 adult f
94496 Michael Ballum DK 55.09 8.67 18-Jul-09 adult m
94495 Sabine Emden D 53.46 7.05 4-Aug-09 adult (3-4 K?) f
55472 Klaus-Dieter Brandenburg D 52.55 14.05 5-Jul-10 adult m
77
78
Appendix 2: Standardized forms used for road transect counts.
observer(s): weather: clear / dust, visibility up to ..…km distant remarks:
date: 2010 which GPS used:
place: country: Morocco
degradation: 0 - no, 1 - few, 2 - much, 3 - complet ely
F=farmland, N=natural steppe, NA=natural steppe art emisia, NH=natural steppe halfa, D=depression, R=ro cks, T=trees, AE=anti-errosion, S=sand, V=village
start/stop Time
km
trees /ha
shrubs/ha
% grass/herbs
% crop
% stone
% sand
habitat type
degra-dation
GPS wpt
N E wpt no. species n age sex distance
: 0
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
78
79
Appendix 3: Standardized forms used for prey transect counts.
name(s) observer(s): % area grass/herbs height grass/herbs (cm)
date: 2010 % area crop heigth of crop (cm) place: Morocco % area stones no. trees per hectare weather: % area sand height of trees (m):
GPS wpt start: N E waypoint no. (start, end) , no. shrubs per hectare
GPS wpt stop: N E GPS used: height of shrubs (m):
starting time:
habitat type: end time:
degradation: 0 - no, 1 - few, 2 - much, 3 - completely degradation:
Species birds: bound to transect flying over Species others: N Plant species:
Passerine spec locust small (<3 cm) Halfa grass
Lark spec. locust medium (3-7 cm) Artemisia
Temminck´s Lark locust large (>7 cm) Noaea
Short-toed Lark active mammal holes: small (<=3 cm diam.) Fredolia
Lesser Short-toed Lark active mammal holes: medium (3-10 cm diam.) Salicornia
Lesser / Short-toed Lark active mammal holes: large (>10 cm diam.) Anabasis
Calandra Lark reptiles thistle
Thekla Lark beetles small (<=1 cm) wheat
Crested Lark beetles medium (1-2 cm) barley
Thekla/Crested Lark beetles large (>2 cm) grass
Hoopoe Lark cricket AE: anti-erosion
Common Swift butterfly D: depression
Barn Swallow F: farmland
Wheatear spec. N: natural steppe
Northern Wheatear NA: steppe artemisia
Desert Wheatear NH: steppe halfa
Red-rumped Wheatear R: rocks
S: sand
T: woodland
V: village
79
80
Appendix 4: Egg measurements of 12 lark species. Length and width (mm) derived
from Harrison & Castell (2004). Weight (g) estimated according to Hoyt (1978),
details see text.
species length breadth weight Skylark (Alauda arvensis) 23.8 17.1 3.7 Crested Lark (Galerida cristata) 22.7 16.8 3.4 Thekla Lark (Galerida theklae) 22.7 16.8 3.4 Short-toed Lark (Calandrella brachydactyla) 19.6 14.6 2.2 Lesser Short-toed Lark (Calandrella rufescens) 20 14.8 2.3 Bar-tailed Lark (Ammomanes cinctura) 21 15.3 2.6 Desert Lark (Ammomanes deserti) 23.3 16.5 3.4 Dupont Lark (Chersophilus duponti) 23 18.4 4.2 Calandra Lark (Melanocorypha calandra) 24.2 17.8 4.1 Thick-billed Lark (Ramphocoris clotbey) 25.7 18.5 4.7 Temminck´s Lark (Eremophila bilopha) 23.2 16.5 3.4 Hoopoe Lark (Alaemon alaudipes) 22.3 17.3 3.6
mean 22.6 16.7 3.4
81
Appendix 5: List of all bird species observed during field trips in Morocco in spring (9 - 22 April) and autumn (9 - 21 September) 2010. Given are
scientific, English, German and Dutch names. Species are ordered taxonomically according to Svensson et al. (2009). In the columns spring and
autumn is indicated if the species was seen during the field trip in this season.
Scientific name English name German name Dutch name spring autumn 1 Tadorna ferruginea Ruddy Shelduck Rostgans Casarca yes yes 2 Coturnix coturnix Quail Wachtel Kwartel yes no 3 Calonectris diomeda Cory´s Shearwater Gelbschnabel-Sturmtaucher Scopoli´s Pijlstormvogel yes no 4 Nycticorax nycticorax Black-crowned Night-
Heron Nachtreiher Kwak yes no
5 Bubulcus ibis Cattle Egret Kuhreiher Koereiger yes yes 6 Egretta garzetta Little Egret Seidenreiher Kleine Silverreiger yes yes 7 Ardea cinerea Grey Heron Fischreiher Blauwe Reiger no yes 8 Ciconia ciconia White Stork Weißstorch Ooievaar yes yes 9 Phoenicopterus ruber Flamingo Rosaflamingo Flamingo no yes 10 Gyps fulvus Griffon Vulture Gänsegeier Vale Gier yes no 11 Pandion haliaetus Osprey Fischadler Visarend no yes 12 Aquila chrysaetos Golden Eagle Steinadler Steenarend yes yes 13 Circaetus gallicus Short-toed Eagle Schlangenadler Slangenarend yes yes 14 Hieraaetus pennatus Booted Eagle Zwergadler Dwergarend yes yes 15 Milvus milvus Black Kite Schwarzmilan Zwarte Wouw yes yes 16 Circus aeruginosus Marsh Harrier Rohrweihe Bruine Kiekendief yes yes 17 Circus pygargus Montagu´s Harrier Wiesenweihe Grauwe Kiekendief yes yes 18 Buteo rufinus Long-legged Buzzard Adlerbussard Arendbuizerd yes yes 19 Accipiter nisus Sparrowhawk Sperber Sperwer no yes 20 Falco tinnunculus Kestrel Turmfalke Torenvalk yes yes 21 Falco naumanni Lesser Kestrel Rötelfalke Kleine Torenvalk yes yes 22 Falco subbuteo Hobby Baumfalke Boomvalk no yes
81
82
23 Falco biarmicus Lanner Falcon Lannerfalke Lannervalk yes yes 24 Alectoris barbara Barbary Partidge Felsenhuhn Barbarijse Patrijs no yes 25 Fulica atra Coot Blässhuhn Meerkoet no yes 26 Chlamydotis undulata Houbara Bustard Kragentrappe Westelijke Kraagtrap yes yes 27 Haematopus ostralegus Oystercatcher Austernfischer Scholekster no yes 28 Recurvirostra avosetta Avocet Säbelschnäbler Kluut yes yes 29 Himantopus himantopus Black-winged Stilt Stelzenläufer Steltkluut yes yes 30 Burhinus oedicnemus Stone Curlew Triel Griel yes yes 31 Cursorius cursor Cream-coloured
Courser Rennvogel Renvogel yes yes
32 Charadrius dubius Little Ringed Plover Flussregenpfeifer Kleine Plevier yes yes 33 Charadrius alexandrinus Kentish Plover Seeregenpfeifer Strandplevier yes no 34 Calidris alba Sanderling Sanderling Drieteenstrandloper no yes 35 Tringa ochropus Green Sandpiper Waldwasserläufer Witgat no yes 36 Actitis hypoleucos Common Sandpiper Flussuferläufer Oeverloper yes no 37 Tringa nebularia Greenshank Grünschenkel Groenpootruiter no yes 38 Numenius phaeopus Whimbrel Regenbrachvogel Regenwulp no yes 39 Chroicocephalus
brunnicephalus Black-headed gull Lachmöwe Kokmeeuw no yes
40 Larus michahellis Yellow-legged Gull Mittelmeermöwe Geelpootmeeuw yes yes 41 Larus audouinii Audouin´s Gull Korallenmöwe Audouins Meeuw yes yes 42 Chlidonias niger Black Tern Trauerseeschwalbe Zwarte Stern no yes 43 Pterocles orientalis Black-bellied
Sandgrouse Sandflughuhn Zwartbuikzandhoen yes yes
44 Pterocles alchata Pin-tailed Sandgrouse Spießflughuhn Witbuikzandhoen yes yes 45 Pterocles coronatus Crowned Sandgrouse Kronenflughuhn Kroonzandhoen yes no 46 Coluba livia Rock Dove Felsentaube Rotsduif yes yes 47 Coluba livia f. domestica Feral Pigeon Straßentaube Stadsduif yes yes
82
83
48 Columba palumbus Wood Pigeon Ringeltaube Houtduif no yes 49 Streptopelia decaocto Collared Dove Türkentaube Turkse Tortel yes yes 50 Streptopelia turtur Turtle Dove Turteltaube Zomertortel yes yes 51 Cuculus canorus Common Cuckoo Kuckuck Koekoek yes no 52 Asio flammeus Short-eared Owl Sumpfohreule Velduil yes no 53 Athene noctua Little Owl Steinkauz Steenuil yes yes 54 Bubo ascalaphus Pharao Eagle Owl Nordafrikanischer Uhu Noordafrikaanse Oehoe no yes 55 Apus apus Common Swift Mauersegler Gierzwaluw yes yes 56 Upupa epops Hoopoe Wiedehopf Hop yes yes 57 Alcedo atthis Kingfisher Eisvogel Ijsvogel yes no 58 Merops apiaster European Bee-eater Bienenfresser Bijeneter yes yes 59 Coracias garrulus Roller Blauracke Scharrelaar yes no 60 Alauda arvensis Skylark Feldlerche Veldleeuwerik yes no 61 Galerida cristata Crested Lark Haubenlerche Kuifleeuwerik yes yes 62 Galerida theklae Thekla Lark Theklalerche Theklaleeuwerik yes yes 63 Calandrella brachydactyla Short-toed Lark Kurzzehenlerche Kortteenleeuwerik yes yes 64 Calandrella rufescens Lesser Short-toed Lark Stummellerche Kleine
Kortteenleeuwerik yes yes
65 Ammomanes deserti Desert Lark Steinlerche Woestijnleeuwerik no yes 66 Ammomanes cinctura Bar-tailed Lark Sandlerche Rosse
Woestijnleeuwerik no yes
67 Melanocorypha calandra Calandra Lark Kalanderlerche Kalanderleeuwerik yes yes 68 Rhamphocoris clotbey Thick-billed Lark Knackerlerche Diksnavelleeuwerik yes yes 69 Emerophila bilopha Temminck´s Lark Saharaohrenlerche Temmincks
Strandleeuwerik yes yes
70 Chersophilus duponti Dupont´s Lark Dupontlerche Duponts Leeuwerik yes yes 71 Alaemon alaudipes Hoopoe Lark Wüstenläuferlerche Witbandleeuwerik yes yes 72 Riparia riparia Sand Martin Uferschwalbe Oeverzwaluw yes yes
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73 Riparia paludicola Brown-throated Martin Braunkehlschwalbe Vale Oeverzwaluw yes no 74 Ptynoprogne rupestris Crag Martin Felsenschwalbe Rotszwaluw yes no 75 Hirundo rustica Barn Swallow Rauchschwalbe Boerenzwaluw yes yes 76 Delichon urbicum House Martin Mehlschwalbe Huiszwaluw yes no 77 Anthus campestris Tawny Pipit Brachpieper Duinpieper yes no 78 Anthus cervinus Red-throated Pipit Rotkehlpieper Roodkeelpieper yes no 79 Motacilla flava Yellow Wagtail Schafstelze Gele Kwikstaart yes yes 80 Lusicina megarhynchos Nightingale Nachtigall Nachtegaal yes no 81 Phoenicurus phoenicurus Redstart Gartenrotschwanz Gekraagde Roodstaart yes no 82 Oenanthe oenanthe Northern Wheatear Steinschmätzer Tapuit yes yes 83 Oenanthe seebohmi Seebohm´s Wheatear Nordafrikanischer
Steinschmätzer Noordafrikaanse Tapuit yes yes
84 Oenanthe leucopyga White-crowned Wheatear
Saharasteinschmätzer Witkruintapuit yes yes
85 Oenanthe leucura Black Wheatear Trauersteinschmätzer Zwarte Tapuit yes yes 86 Oenanthe deserti Desert Wheatear Wüstensteinschmätzer Woestijntapuit yes yes 87 Oenanthe moesta Red-rumped Wheatear Fahlbürzel-Steinschmätzer Roodstuittapuit yes yes 88 Saxicola rubetra Whinchat Braunkehlchen Paapje yes no 89 Turdus merula Blackbird Amsel Merel yes yes 90 Sylvia atricapilla Blackcap Mönchsgrasmücke Zwartkop yes no 91 Sylvia communis Whitethroat Dorngrasmücke Grasmus yes no 92 Sylvia melanocephala Sardinian Warbler Samtkopfgrasmücke Kleine Zwartkop yes yes 93 Sylvia conspicallata Spectacled Warbler Brillengrasmücke Brilgrasmus yes no 94 Sylvia cantillans Subalpine Warbler Weißbartgrasmücke Baardgrasmus yes no 95 Scotocerca inquieta Scrub Warbler Wüstenprinie Maquiszanger no yes 96 Cisticola juncidis Zitting Cisticola Cistensänger Graszanger yes no 97 Hippolais polyglotta Melodious Warbler Orpheusspötter Orpheusspotvogel yes no 98 Hippolais pallida Olivaceous Warbler Blaßspötter Vale Spotvogel yes no
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99 Phylloscopus trochilus Willow Warbler Fitis Fitis yes no 100 Phylloscopus sybilatrix Wood Warbler Waldlaubsänger Fluiter yes no 101 Regulus ignicapillus Firecrest Sommergoldhähnchen Vuurgoudhaan yes no 102 Troglodytes troglodytes Wren Zaunkönig Winterkoning yes no 103 Pycnonotus barbatus Common Bulbul Graubülbül Grauwe Buulbuul no yes 104 Cercotrichas galactotes Rufous Bush Robin Heckensänger Rosse Waaierstaart no yes 105 Muscicapa striata Spotted Flycatcher Grauschnäpper Grauwe Vliegenvanger yes yes 106 Ficedula hypoleuca Pied Flycatcher Trauerschnäpper Bonte Vliegenvanger yes no 107 Parus major Great Tit Kohlmeise Koolmees yes no 108 Lanius excubitor Great Grey Shrike Raubwürger Klapekster yes yes 109 Lanius senator Woodchat Shrike Rotkopfwürger Roodkopklauwier yes no 110 Turdoides fulva Fulvous Babbler Akaziendrossling Bruingele Babbelaar no yes 111 Pica pica Magpie Elster Ekster yes no 112 Garrulus glandarius Jay Eichelhäher Gaai yes no 113 Corvus corax Common Raven Kolkrabe Raaf yes yes 114 Corvus ruficollis Brown-necked Raven Wüstenrabe Bruinnekraaf yes yes 115 Passer domesticus House Sparrow Haussperling Huismus yes yes 116 Passer hispaniolensis Spanish Sparrow Weidensperling Spaanse Mus yes yes 117 Fringilla coelebs Chaffinch Buchfink Vink yes yes 118 Carduelis carduelis Goldfinch Stieglitz Putter yes yes 119 Carduelis chloris Greenfinch Grünfink Groenling yes yes 120 Serinus serinus Serin Girlitz Europase Kanarie yes no 121 Bucanetes githagineus Trumpeter Finch Wüstenfink Woestijnvink yes yes 122 Miliaria calandra Corn Bunting Grauammer Grauwe Gors yes no 123 Emberiza cia Rock Bunting Zippammer Grijze Gors yes no
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Hiermit versichere ich, dass ich diese Arbeit selbstständig verfasst und keine anderen als die angegebenen Quellen und Hilfsmittel benutzt habe. Außerdem versichere ich, dass ich die allgemeinen Prinzipien wissenschaftlicher Arbeit und Veröffentlichung, wie sie in den Leitlinien guter wissenschaftlicher Praxis der Carl von Ossietzky Universität Oldenburg festgelegt sind, befolgt habe. Oldenburg, 28 March 2011