Ciucci, P., Boitani, L., Francisci, F., and Andreoli, G. (1997). Home range, activity and movements of a wolf pack in central Italy. Journal of Zoology (London) 243: 803-819.

Keywords: 8IT/activity/Canis lupus/home range/Malme/movement/radio telemetry/wolf

Abstract: Home range, habitat use, activity and movement patterns were studied in a pack of wolves in a mountainous region of Abruzzo, central Italy from June 1986 to March 1987. The home range, estimated by the minimum convex polygon from 421 radio locations, measured 197 km2 and comprised several infrastructures and areas of human presence, including four garbage dumps and two offal sites. Core areas, calculated by the harmonic mean method, were located toward the centre of the home range where human disturbance and road density were lowest but forest cover was highest. During the time-span of the study, home-range use and movement patterns suggested a marked centrality in spatial behaviour and traditionality in retreat areas year-round, both during pup-rearing season and the following months. In addition, by being essentially nocturnal, resident wolves appeared to adopt tactics of temporal segregation from people to exploit food resources safely in the proximity of human settlements. Overall activity correlated with distance travelled (r = 0.90, P << 0.001), and corresponded to cyclic nocturnal movements from retreat to feeding areas. Wolf movement rate between 20:00 and 04:00 h averaged 2.5 Mi but varied up to about 8 km/h, and daily distance travelled (X = 27 km/night; range 17-38 km/night) mostly depended on the location of traditional feeding sites. Home-range configuration, habitat use, activity and movements all appeared highly integrated so as to represent the most functional compromise between avoidance of human interference and exploitation of the available food resources.

J. Zool., Lond. (1997) 243, 803-819

Home range, activity and movements of a wolf pack in central Italy

P. CIUCCI, L. BOITANI*, F. FRANCISCI’ A N D G. A N D R E O L I ~

Universitu di Roma ‘La Sapienza ’, Dipartimento di Biologia Animale e dell’Uomo, Viale dell’Universit2 32, Roma 001 85, Italy

(Accepted 5 February 1997)

(With 4 figures in the text)

Home range, habitat use, activity and movement patterns were studied in a pack of wolves in a mountainous region of Abruzzo, central Italy from June 1986 to March 1987. The home range, estimated by the minimum convex polygon from 421 radio locations, measured 197 km2 and comprised several infrastructures and areas of human presence, including four garbage dumps and two offal sites. Core areas, calculated by the harmonic mean method, were located toward the centre of the home range where human disturbance and road density were lowest but forest cover was highest. During the time-span of the study, home-range use and movement patteins suggested a marked centrality in spatial behaviour and traditionality in retreat areas year-round, both during pup-rearing season and the following months. In addition, by being essentially nocturnal, resident wolves appeared to adopt tactics of temporal segregation from people to exploit food resources safely in the proximity of human settlements. Overall activity correlated with distance travelled (r = 0.90, P << 0.001), and corresponded to cyclic nocturnal movements from retreat to feeding areas. Wolf movement rate between 20:00 and 04:OO h averaged 2.5 Mi but varied up to about 8 km/h, and daily distance travelled (X = 27 kmfnight; range 17-38 kndnight) mostly depended on the location of traditional feeding sites. Home-range configuration, habitat use, activity and movements all appeared highly integrated so as to represent the most functional compromise between avoidance of human inteference and exploitation of the available food resources.

Introduction

Since the late sixties, wolf research in Europe has been essentially aimed at conservation (i.e. distribution and status of populations, conservation needs, etc.) (e.g. Pulliainen, 1965, 1980, 1985; Zimen & Boitani, 1975, 1979) and has rarely included intensive ecological studies of resident wolves. In particular, although radio-tracking techniques have been applied to wolf research since the late sixties (Kolenosky & Johnston, 1967), very few reports on radio-tracking studies of European wolves have been published up to now; these include the early work by Zimen and Boitani in Italy (Zimen, 1978; Zimen & Boitani, 1979; Boitani, 1982) and the more recent study in Spain by Urios, Vila & Castroviejo (1993), Vila, Urios & Castroviejo (1993, 1995). Nevertheless, radiotelemetry stands as one of the most powerful tools to get insight into the ecology of an elusive species such as the wolf (Mech, 1974). Especially in environments intensively used by humans, thorough and reliable data on space and habitat use by wolves can be obtained only by radiotelemetry, and this information appears critical not only to understanding the ecology of the species, but also to planning effectively for its conservation. As wolves are slowly recolonizing portions of their former range throughout Europe

‘Present address: Via S. Marta 23, Firenze, Italy *Present address: Agriconsulting S.p.A., Via L. Luciani 41, Roma, Italy *Address for correspondence: e-mail: boitani@pan.bio.uniromal .it

803

0 1997 The Zoological Society of London

804 P. CIUCCl E T A L .

(Promberger & Schroeder, 1993), studies need to be carried out on their ecology in the intensively used European environments. When compared with the ecology of wolves in areas of North America with low human populations, these studies could prove extremely useful in planning the conservation and management of wolves worldwide. However, quantification of features such as range and habitat use by wolves in Europe has been minimal. We hereby report on home range, habitat use, movements and activity of a wolf pack studied by radio-tracking one of its members in the Abruzzo mountains of Italy, where wolves have been surviving at close quarters with humans since prehistoric times. This study constitutes part of a broader research investigation on wild canids in the same region (Andreoli, 1987; Ciucci, 1987; Francisci et al., 1989, unpubl. rep. to the National Institute of Wildlife Biology; Boitani et at., 1989, 1991, 1995) whose data corroborated the findings reported herein.

Study area and methods

The study area is located in the Sirente mountain group (Fig. 1), one of the main Apennine ridges that crosses the region of Abruzzo (42"N, 13'30'E). Two major plateaus, Altopiano delle Rocche (mean elevation 1300 m) and Valle Subequana (mean elevation 800 m) are located in the central part of the study area, and are connected through a system of valleys and mountain ridges up to 2438 m. Several small villages are scattered throughout the area, but because people are essentially aggregated around them, large portions of the territory are void of human presence. Based on the municipalities in the study area, local human density averages (?S.D.) 28.5 t 21.7 inhabitantsh', while densities calculated at the provincial (Aquila) and regional (Abruzzo) levels are 64.4 and 120.2 inhabitantskm2, respectively (Del Papa & Corti, 1993). With the tourist season, human presence in the area increases significantly during summer. Major paved roads cross the 2 plateaus, and several dirt roads reach side valleys and higher altitude pastures, although they are used almost exclusively by shepherds during the grazing period (May-October). Mean annual temperature is 7.6 "C, ranging from - 1.4 "C in January to 16.2 "C in August, although temperatures below -20 "C are not unusual from January through March. The presence of snow extends approximately from December through April, with greatest depths in February-March averaging about 120 cm at 1800 m a d . Vegetation types are dominated at higher altitudes by pure stands of beech (Fagus sylvatica) forests and, at lower altitudes, by mixed forests where other species (Quercus, Fraxinus, Acer) predominate. Valley bottoms are covered mostly by abandoned fields, pastures and fields cultivated seasonally with potatoes and cereals. Above 1800 m, the beech forests give way to alpine prairies that have been severely degraded by centuries of grazing. Large ungulates were almost totally exterminated before the end of the last century; during the years of the study, only roe deer (Capreolus capreolus) and wild boar (Sus scrofa) were present in the area, the former being very rare and the latter steadily increasing following reintroduction efforts by hunting associations during the early 1980s. European hares (Lepus europaeus) were quite common, and both wolves and feral dogs were simultaneously present in the study area (Boitani et al., 1995). From May to October, a few thousand sheep are grazed in the alpine pastures, generally guarded by shepherds with guard dogs and kept in enclosures at night. Due to the karst nature of the terrain, surface water is extremely rare during summer, with the exception of artificial water pools maintained for livestock and a few, small streams in valley bottoms. In the proximity of the main villages, several rubbish tips receive daily truck loads of all kinds of food remains including slaughter offals, and represent traditional feeding sites for both wild and domestic animals (Boitani et al., 1995).

The presence o f wolves in the area has been confirmed since 1973 (Zimen & Boitani, 1975; Boitani & Fabbri, 1983), but interviews with local residents have suggested that wolves have always been there. From 1984 to 1988, during the years o f a broader study (Francisci et al., 1989, unpubl. rep. to the National Insitute of Wildlife Biology; Boitani et al., 1995), 2 wolf packs were present in the area. Radio-tracking data and following tracks in the snow during winter revealed that they occupied exclusive temtories in the southern (Val d'Arano pack) and northern (S. Pellegrino pack) portion of the study area. Radiotelemetry data (June 1986-March 1987) were collected from one adult male of the S. Pellegrino pack. Radio locations from one wolf can be considered indicative of the whole pack (Kolenosky & Johnston, 1967; Fuller & Keith, 1980; Fritts & Mech, 1981), and the high level of association that we found between the radio-equipped male and the other members of the pack tends to confirm this

MOVEMENTS AND ACTIVITY OF WOLVES IN CENTRAL ITALY 805

FIG. 1. Location of the study area.

assumption, especially with regard to home range, habitat use and movements. Until the winter of 1988, at least 5 wolves were still present in that pack, and in September 1989 the Forest Corps retrieved the carcass of the radioed male, apparently poisoned (Guberti, pers. comm., National Institute of Wildlife Biology).

To capture wolves, spring-activated foot snares (Aldrich Trap Co.) were set along trails and at feeding sites, and were checked once or twice a day depending on site accessibility. A mixture of ketamine hydrocloride (Ketalar, Parke-Davis) and xylazine hydrocloride (Rompun, Chemargo Corp.) at about 1.7 m1/30 kg (Harthoorn, 1976) was administered by a blow gun (Telinject) to immobilize captured animals, which were fitted with a 150 MHz radiocollar (c. 250 8). Radio locations were determined by triangulation from fixed stations throughout an extensive road network across the study area using one vehicle with a cartop, 5-elements Yagi antenna system. Each location was centred within a squared polygon error with a side of 250 m; depending on field conditions, relocations whose accuracy was subjectively evaluated as being lower were not included in the analysis (Boitani et al., 1995). At each relocation, activity was detected as fluctuations in signal strength.

Radio-tracking data were gathered according to 2 sampling strategies (see Laundre & Keller, 1984): (i) single (point) locations, with relocation interval of 2 12 hours, utilized to determine home range and habitat use, and (ii) sequential locations, recorded by instantaneous sampling (Altmann, 1974) at 10 min intervals during continuous monitoring sessions, used to estimate activity and movements. Home-range size was estimated by the Minimum Convex Polygon, MCP, (Mohr, 1947:), whereas areas of higher use within the home range (i.e. core areas) were determined with the Harmonic Mean Method (Dixon & Chapman, 1980) applied to a subsample of radio (point) locations. The harmonic mean centre was used to estimate the home-range centre of activity. The subsample of' radio locations did not include extreme locations (i.e. outliers) (Samuel et al., 1985), and was randomly selected to eliminate the bias due to autocorrelation of locations (cf. Swihart & Slade, 1985). For home-range computations we used the HOME RANGE program by Samuel et al. (1985), where core areas (sensu Spencer & Barret, 1984), identified as those portions of the home range whose observed use exceeds a uniform expected one, are tested by Kolmogorov-Smirnov (Samuel et al., 1985). Retreat areas (Zimen, 1978) were defined as those portions of the home range encompassing 25% of the harmonic mean utilization volume. To analyse internal use of the home range further, we used a GIS (ARC-INFO)/HOME-RANGE integration (Boitani et al., 1989). Vegetation types were identified according to the dominant vegetative structure and were defined broadly to account for the effect of triangulation error on detecting habitat selection (White & Garrott, 1986). To estimate habitat use, we adopted a x2 procedure to compare habitat availability between the MCP home range and areas of higher use (i.e. delineated

806 P. CIUCCI ET A L

by harmonic mean contours). Use of the different vegetation types was further investigated comparing expected with observed utilization frequencies (Neu et al., 1974), with expected frequencies calculated according to availability within the MCP home range.

Activity was expressed as both the percentage of active radio locations per hour and the average distance travelled per hour (Andelt & Gipson, 1979; Sumner, Hill & Wooding, 1984). To estimate activity budgets, we divided the 24-hour day into 4 time periods: dawn, daylight, dusk and night. Dawn and dusk periods ( 2 hours each) were defined on a monthly basis, respectively, as one hour before and after local sunrise and sunset times, respectively, and length of daylight and night periods varied accordingly. Differences in resting and active status within each of the 4 periods were tested by x2 goodness-of-fit based on 50:50 expected frequencies. The 24-hour activity estimate was obtained by a weighted sum of active radio locations across the 4 time periods (Green & Bear, 1990). Distances travelled per hour were calculated as the sum of the Euclidean distances between radio locations recorded at each 10 min interval, and were averaged across all continuous monitoring sessions. During one week of continuous monitoring, full-night monitoring was alternated to daylight relocations to control the wolf position. For full-night monitoring sessions only, daily movements were expressed as the total distance travelled from the beginning to the end of nocturnal movements. Two types of problems could have occurred during continuous monitoring sessions: first, because not all radio locations could be obtained by triangulation every 10 rnin interval, occasionally some of them represented estimates from a single bearing (gaps); second, animal movement during triangulation might have increased telemetry error (Schmutz & White, 1990). In the first case, location estimates from a single bearing were supported by linear interpolation between the 2 known (i.e. triangulated) locations before and after the gap; however, this procedure was adopted only for gaps not exceeding 5 2 consecutive sampling intervals in length (i.e. 5 20 min), and hours (sessions) with gaps 2 30 min were not used to analyse mean distance travelled per hour (daily movements). In the second case, we believe that the extensive road system which allowed quick triangulations, coupled with the fact that wolves tended to use the same traditional routes for travel, made radio location error due to animal movement small enough to be considered negligible in relation to the total distance travelled during the night.

Die1 activity patterns were compared to expected uniform ones by the Kolmogorov-Smimov test, and mean distances travelled in different periods of the day, or to reach different activity areas, were compared by the Mann-Whitney U-test. Onset of activity was determined as the average first hour after diurnal resting with 2 30% of active radio locations, followed by at least the same degree of activity per hour. Analogously, cessation of activity was determined as the average last hour after nocturnal activity with 2 70% of resting radio locations followed by at least the same degree of inactivity per hour. Minimum length of visits to traditional feeding sites was estimated from the first and the last radio locations at known feeding sites, and was calculated only for visits involving at least 2 consecutive sampling intervals (i.e. 2 10 min). The number of individuals associated with the radio-equipped wolf, as determined from direct observations, has to be considered a minimum estimate since it was likely that other wolves might always have been undetected. Associations established by wolf-howling were determined by simultaneous presence of the radio-equipped wolf at the howling location, and a gross estimate of the minimum number of individuals was obtained by counting single voices as they entered the chorus ( Josh , 1967).

Results

Pack composition and associations

As from howling and snow-tracking data, it was estimated that the S. Pellegrino pack produced at least 3 pups in spring 1986; the following winter it was composed of at least 5 adultslsubadults. One adult male (M05, at least 3-4 years) from the same pack was captured, fitted with a radiocollar and released on 3 June, 1986. In the period during which M05 was monitored by radio-tracking (June 1986-March 1987), he was observed 9 times, always in association with at least 1-4 other pack members: a total of 2 (3 times), 3 (4 times), 4 (once) and 5 (once) wolves were observed together. In all

MOVEMENTS AND ACTIVITY OF WOLVES IN CENTRAL ITALY

cases, wolves were spotted while travelling in the outer portion of their home range. During the same period, elicited or spontaneous howlings from the S. Pellegrino pack were recorded on 11 occasions, 10 of which comprised more than one individual (a maximum of 4 adults/subadults and 3 pups) from the same location of M05. All howlings were recorded within the core area of the pack’s home range (see below).

807

Home range and habitat use

As from 42 1 radio locations (08/06/86- 15/03/87), the MCP pack’s home range measured 197 km2. It ranged in elevation from 520 m in the south-eastem to > 2000 m in the central part, and included 6 villages, 4 rubbish tips, 2 slaughter offal sites (Fig. 2). Based on local municipalities, mean (+S.D.) human densities within the MCP home range and in the whole study area were 15.7 -+ 2.6 (n = 4) and 25.5 ? 2 I .7 (n = 8) inhabitants/km*, respectively, although the difference was not significant (t-test, P > 0.05). As from a random subsample of 123 radio locations analysed with the Harmonic Mean method, the core area of the home range represented about 15% of the MCP home range; it did not include any villages or intensively used paved roads and encompassed one heavily loaded rubbish tip. From June through March, the pack’s movements focused on one single centre of activity, which shifted less than 1 km from summer (June-September) to winter (October-March). Summer and winter home ranges overlapped considerably and so did the seasonal core areas, although in winter the core area appeared more fragmented than in summer (Fig. 3). The internal parts of the home range used more frequently by wolves were characterized by proportionally higher availability of forest cover and lower road density (Table I). Retreat areas (Fig. 2) featured more than 99% of forest cover, and did not include paved roads. The two retreat areas most frequently used (S, and S2, see Fig. 2) were both localized on top of isolated mountain ridges at about I100 m elevation. They were characterized by being a considerable distance from any human settlement, absence of roads, thick vegetation of young stands of deciduous forest (Fruxinus ornus, Quercus robur, Acer spp.. Ostrycr curpin$oliu) with dense understorey, and relatively flat, broken terrain with rocky outcrops. In addition, the retreat area encompassing the home-range activity centre (S,, Fig. 2) was localized in close proximity to S. Pellegrino lake, a small artificial pool of water maintained for livestock, one of the few water sources available in the area during summer months.

Through the 24-hour period, observed use of the vegetation types differed from what would have

TARLE 1 Summur?; ofthe characteri.rtics of the S. Pellegrino wolfpack home range (Ahruzzo, central Italy), estimatedfrom the Minimiin Convex Polygon (MCPJ and the Harmonic Mean (HM) methods applied to rudiotelemerrv data from one adult male during Jime

1986-Murch 1987

Home-range method

Vegetation types (9%)” Area Roads (km’) Wood Alp. prairie Shrubland Pastures Cultivations (krn’)

MCP 197 36.5 35.5 11.6 15.8 0.6 ~

HM 95% isopleth 92 64.3 17.8 13.2 4.8 0 8.5 Core Area (CA) 30 72.7 13.9 13.1 0.3 0 4.7 25% isopleth 3 99.5 0.3 0.2 0 0 0.4

“MCP VS. 956 HM, P < 0.001; 95% HR.1 VS. CA, P > 0.05; CA VS. 25% HM, P < 0.001 ’95% HM vs. CA, P < 0.001

808 P. CIUCCI E T A L .

rb----- Paved roads

? MCP home range

HM home-range contours

--& HM Core Area *--

~~

HM activity centre

0 Dump sites

Slaughter offals

@%B ViHages

FIG. 2 . Location and configuration of the S. Pellegrino wolf pack home range (June 1986-March 1987) in Abmzzo, central Italy, as estimated from the Minimum Convex Polygon and Harmonic Mean methods applied to radiotelemetry data on one adult male. The map shows relative positions of retreat areas, traditional feeding sites, villages and main paved roads. Curved lines (contours) refer to different proportions of the harmonic mean utilization volume (for symbols see text and Table 111).

MOVEMENTS AND ACTIVITY OF WOLVES IN CENTRAL ITALY 809

%A Ovindol

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Aie’li F\ V A L L E b-

HARMONIC MEAN HOME RANGE ,-.- .*- June-October

HARMONIC MEAN CENTRE

fi J une-Octobe r

November-March * November-March

FIG. 3. Location, configuration and activity centres of summer (June-September) and winter (October-March) harmonic mean home ranges of the S. Pellegrino wolf pack (Abruzzo, central Italy) during June 1986-March 1987. (Symbols as in Fig. 2).

been expected according to their availability (x2 = 290, d.J = 4, P << 0.001), as wolves preferred forest cover and avoided all types of open vegetation (shrubland, alpine prairie, pastures and cultivated fields) (Table 11). The same pattern of habitat selection was also revealed for daylight and night periods separately (respectively, x2 = 256, d.5 = 4, P << 0.001; x2 = 70.3, d.f. = 4, P < 0.001), with forest cover preferred in both cases (Table 11). However, habitat use changed from daylight to night (x2 = 44.7,

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MOVEMENTS AND ACTIVITY OF WOLVES IN CENTRAL ITALY 81 1

d.$ = 4, P << 0.001) as use of open vegetation increased from 9.5% (n = 19) to 37.4% (n = 83) between daytime and night, respectively (Table 11). As compared to forest cover, however, open vegetation appeared to be still avoided during the night, with the sole exception of shrubland which was used according to its availability (Table 11).

Activity and movements

In the period from 8 June, 1986 to 15 November, 1986, 29 continuous monitoring sessions were recorded, ranging in length from 4 to 13 hours, for a total of 183 hours. The corresponding 1099 radio locations were distributed 47% (n = 516) during night, 38.5% (n = 423) during daylight, and 14.5% (n = 160) during crepuscular periods (dawn: n = 84, dusk: n = 76). Overall, M05 was active and resting, respectively, 53% and 47% of the time ( x 2 = 1.4, d.,f. = 1, P > 0.1). However, activity was more frequent at night (81%, n = 419; x2 = 200, d.f. = 1 , P << 0.001), and less frequent both in daylight ( I I % , n = 46; x2 = 259, d.$ = 1, P << 0.001) and dusk (38%, n = 29; x2 = 4.2, d.f. = 1, P < 0.05) periods, whereas active and resting status were equally distributed at dawn (57%, n = 48; x2 = 1.74, d.& = 3, P > 0.1). With regard to the four daily periods simultaneously, activity was distributed preferentially during the night (June-November: x2 = 159, d.,f.=3, P << 0.001), the same being true both for summer (June-September: x2 = 15.2, d:f. = 3, P < 0.005) and autumn (October-November: x2 = 1 19, d.$ = 3, P << O.OOl), although the two seasonal distributions differed for an increase in daylight activity during summer (x2 = 78.4, d.$ = 3, P << 0.001).

Die1 activity patterns confirmed the preponderance of nocturnal activity (Kolomogorov-Smirnov D = 0.26, P < 0.001), as this began in the evening, continued through the night and ceased in the morning (Fig. 4). Mean onset time of activity was 18:25 t 00:40 h (range 17:OO-22:OO h; n = 7), while mean cessation time was 0 6 4 5 5 00:40 h (range 05:OO-09:OO h; n = 8). Activity indicated by mean distance travelled per hour paralleled that detected from fluctuations in signal strength (r = 0.90, P << 0.001), with absence of movements during daylight and greatest distances travelled in the night (Kolomogorov-Smirnov D = 0.37, P < 0.001). At dawn and dusk, however, the relationship between the two activity measures did not necessarily hold (r = 0.53, P > 0.1, from 05:00 to 07:00 h and from 17:OO to 19:OO h), the discrepancies being particularly relevant around activity’s onset and cessation times, when activity up to 80% usually corresponded to less than 800 m travelled per hour. Mean (5S.D.) distance travelled per hour was 1.1 5 3.2 km (n = 168), but it was higher from 20:00 to 04:00 h (2.5 2 2.1 km, n = 74) than from 05:OO to 19:00 h (0.3 5 0.9 km, n = 94) (Mann-Whitney U = -7.99, P<<O.001). Greatest distances travelled per hour ranged from 6.1-7.6 km (n = 5 ) and corresponded to movements between 0O:OO and 06:00 h.

In 10 out of 29 continuous monitoring sessions, it had been possible to record entire nocturnal movements (Table 111). Distance travelled per night averaged (2 S.D.) 27.4 5 6.9 km (n = lo), ranging from 17 to 38 km. During nocturnal movements, wolves reached the outer portion of the home range using traditional travel routes, and in all cases travel began from, and ended at, traditional retreat areas in the centre of the home range. The distance between starting and end points of nocturnal movements averaged (2S.D.) 3.3 2 4.2 km (n = 10) and ranged from 0.3 to 11.5 km (Table 111), representing from 0.8 to 39.6% of the total distance travelled during the night; the two measures were not correlated (r = 0.049, n = 10, P > 0.8). In 60% ( n = 6) of cases, nocturnal movements began from and ended at the same location, which was the most used retreat site and corresponded to the harmonic mean activity centre (S,, see Table 111, Fig. 2). In addition, as from seven consecutive days of continuous monitoring, nocturnal movement began from the previous night’s movement’s endpoint, as the wolf did not change his location during daylight (22-26 October: Table 111).

812

T

P. CIUCCI E T A L .

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- Activity

h

60 1. > c .- .-

40 5

20

n - 0 0 0 0 0 0 0 0 0 0 9 9 9 9 9 9 9 9 9 9 ~ L O ~ ~ $ ~ O c u m c u & c u c u

FIG. 4. Die1 activity patterns of one radio-equipped wolf in Abmzzo, Italy, during June-November 1986. At each hour, activity is expressed both as the proportion of active radio locations and the distance travelled averaged across continuous monitoring sessions. Plotted values for each hour (e.g. 0O:OO h) represent activity recorded in the following hour (i.e. 0O:OO- 0059 h). Vertical lines above columns represent standard errors in distance travelled, and numbers below abscissa values are sample sizes (i.e. number of continuous monitoring sessions) for each hour. Dashed vertical lines include the range of local sunset and sunrise times during the span of the study.

TABLE 111 Characteristics of nocturnal movements as estimated by sequential relocations at 10-miri intervals during 10 continuous

monitoring sessions (25 June-28 October 1986) on a radio-equipped adult wolf in Abruzzo, Italy

Area of Starting Ending Distance starting- Total distance Feeding sites Minimum Date activity site" site" ending sites (km) travelled (km) visitedb associates"

25 Jun. 30 Aug.

6 Oct. 22 Oct. 23 Oct. 24 Oct. 25 Oct. 26 Oct. 27 Oct. 28 Oct.

Altop. Rocche V. Subequana V. Subequana V. Subequana Altop. Rocche Altop. Rocche Altop. Rocche V. Subequana Altop. Rocche V. Subequana

I .5 3.2 0.5

11.5 10.6 3.3 I .2 0.3 0.5 0.3

16.96 28.17 31.94 30.69 26.76 27.63 18.18 35.59 2 1.65 30.54

a See Fig. 2 D = rubbish tip, C = slaughter offal site; see Fig. 2 As determined by spontaneous or elicited howling (h) and/or visual observation (v); n.r. = not recorded

MOVEMENTS AND ACTIVITY OF WOLVES IN CENTRAL ITALY 813

Nocturnal movements were generally aimed at alternative foraging areas located in two adjacent valley systems (Altopiano delle Rocche and Valle Subequana) at the opposite extremes of the NW-SE home-range diameter (Fig. 2). Daily travel to these valleys appeared to be mutually exclusive and, although no clear periodicity was revealed in these visits, both areas were visited an equal number of times (Table 111). Mean (&S.D.) distance travelled to reach Valle Subequana (32.6 2 4 km, n = 5 ) was greater than that travelled to reach Altopiano delle Rocche (22.2 2 4.8 km, n = 5 ) (Mann-Whitney U = -2.61, RO.01). Ninety percent (n = 9) of nocturnal movements involved visits to traditional feeding sites such as garbage dumps and slaughter offal sites; 33% of these movements involved at least one feeding site, and 67% at least two (Table ITI), with an average of 1.8 feeding sites per nocturnal movement. Minimum time spent foraging at traditional feeding sites per nocturnal movement averaged (5S.D.) 53 2 32 min, ranging from 30 to 110 min (n = 6). During the night, the wolves were often monitored and/or spotted as they crossed large villages such as Rocca di Mezzo and Gagliano Aterno or while travelling along main paved roads. In October, during full-night monitoring sessions, wolves were spotted four times (Table III), and in all cases at least 1-3 adults/subadults were associated with M05 at or in the proximity of traditional feeding sites.

Discussion

The results show the nature and the mechanisms of the wolf‘s adaptation to an environment altered by human activity. Survival tactics of resident wolves apparently involve a process of fine-tuned adaptation to local conditions, where home-range location and configuration, habitat use, activity and movements are all highly integrated in such a way as to make the best functional compromise between two contrasting situations: (i) the necessity to exploit the main food resources available (i.e. rubbish tips in proximity of human settlements), and (ii) the need to avoid any direct form of human pressure and interference.

Home range and habitat use

Home-range use and configuration reflected the wolves’ detailed knowledge of the environment, including location and rhythms of human activities. The wolf pack home range included several human activity centres (villages, roads, agricultural areas), although these were generally located toward its outer part, where wolf presence was minimal and essentially nocturnal. Number and location of rubbish tips visited by the wolves appeared critical in shaping their spatial behaviour: the NW-SE direction along which most rubbish tips were found coincided with the home range’s longest diameter (see Fig. 2), even though the topographic features of the area (mountain ridges, valley bottoms) appeared critical in shaping the boundaries of the wolves’ territory. Home-range size was comparable with estimates previously reported for the same region in Italy, from about 120 to 200 km2 (Boitani, 1982, 1992), although significant variability has been detected for packs living under similar environmental conditions (e.g. from 75 to >300 km2; Boitani, pers. comm.). However, home-range size estimates may vary significantly due to either the sampling strategy (Swihart & Slade, 1985; Gese, Anderson & Rongstad, 1990) and the method employed (e.g. Kleiman & Brady, 1978), or the number of data points included in the estimate (Bekoff & Mech, 1984). Therefore, meaningful comparisons can only be made between reports clearly stating the methodology adopted, and these are limited in the European literature. From studies in North America, home-range size appears related to prey density (Fuller 1989), wolf density (Fritts & Mech, 1981; Peterson, Wooligton & Bailey, 1984; Ballard, Withman & Gardner, 1987) and, to some extent, to pack size (Peterson et al., 1984; Messier, 1985;

814 P. ClUCCI E T A L .

Ballard et al., 1987). However, in the absence of wild prey and in environments highly modified by human presence, it does not seem reasonable to expect this relationship to hold necessarily. Under these conditions, other factors such as the nature and dispersion of food resources, human interference and topography may play a significant role in determining home-range size. Whereas the size of the S. Pellegrino pack home range was probably also a function of the number of rubbish tips required by the entire pack, its boundaries, as estimated by the MCP method, appeared mostly delimited by topography and human settlements and infrastructures. Nevertheless, territorial behaviour cannot be discounted in shaping home-range size and configuration, as both other wolves and feral dogs were simultaneously present in the same area (Boitani et al., 1995): S. Pellegrino pack’s home range partially overlapped with that of feral dogs (see Fig 15.3 in Boitani et al. 1995: 224) exclusively in the area of highest human density and where one of the most frequently visited garbage dump was located (D1, Fig. 2), while it did not overlap with that of another wolf pack to the south (Ciucci, 1987; Boitani et al., 1995). During the year of the study, no field evidence was obtained of affiliative interaction between the S. Pellegrino wolves and feral dogs, which eventually might have led to interbreeding, as reported by Zimen (1978) and Boitani (1986) for a she wolf and a vagrant dog in the Maiella range. However, two feral dogs of the studied group were suspected of having been killed by S. Pellegrino wolves in encounters which were probably territorial (Boitani et al., 1995).

The wolves did not use the entire home range uniformly, and their presence was most frequent in areas located toward the centre, with no villages, lower road density and proportionally more extensive forest cover. These corresponded to the core areas of the home range and included the diurnal retreat areas (Zimen, 1978; Boitani, 1982), where topography and distance from human settlements appeared to reduce disturbance by people. Throughout the entire study period, only one centre of activity was detected and this corresponded to the most used retreat area: its location appeared to represent an ideal spatial compromise between the closest proximity to all garbage dumps regularly visited by the wolves and the maximum distance from the villages in the area. However, other variables as well could have influenced the location of the retreat area as relevant habitat features of this location included proximity to one of the few water sources available during the summer, a mean elevation higher than the surrounding areas, dense and continuous forest cover, and distance from roads regularly used by humans. A single centre of activity was maintained throughout the year, and no seasonal change in internal use of the home range was observed. We did not record any sequential shifting in den and rendezvous locations during summer, nor in homesite locations during autumn and winter, as expected based on findings from North America (e.g. Kolenosky & Johnston, 1967; Pimlott Shannon & Kolenosky, 1969; Mech, 1970; Harrington & Mech, 1982a, b), as well as from other regions of Italy where wolves live in areas of lower human and higher prey densities (Ciucci, 1994). This strongly suggests that availability of optimal retreat areas might be a limiting factor for wolves living in environments altered by human presence. There were not many places within the S. Pellegrino pack home range that could have met the same spatial and habitat requirements as those featured by the retreat area most frequently used; this therefore comprised den, rendezvous and homesites year-round. On the other hand, although this does not necessarily represent an alternative explanation, it could have been the high predictability in space and time of the main food resources (i.e. rubbish tips) to have prompted the observed centrality in space use, as sequential shifting of homesites’ locations could have interfered with travel and movement patterns to and from traditional feeding sites within the home range. The same reasons might also respond to the absence of seasonal shifts both in location and internal use of the home range, as reported for areas where wolves appear to follow movements of prey species on a seasonal basis (Fritts & Mech, 1981; Ballard et al., 1987; Potvin, 1987). However, even though the systematic and frequent visits to the rubbish tips (see Table 111) pinpoint their importance as

MOVEMENTS AND ACTIVITY OF WOLVES I N CENTRAL ITALY 815

food sources, support for our hypothesis is incomplete as we did not quantitatively assess to what extent other less predictable food sources such as wild boar could have influenced the wolves’ feeding ecology.

Whereas in environments with low human populations, habitat use by wolves may essentially reflect the search for prey, in the conditions studied here it seemed rather an additional means of increasing safety from humans while living in close proximity to them. Forested areas were essentially selected as cover during daytime, as also reported for wolves living in similar ecological situations (Boitani, 1982; Vila et al., 1993). But in most of these conditions, forested areas do not provide enough food and wolves prefer to forage at more predictable food sources located in the proximity of human centres (Zimen, 1978; Macdonald, Boitani & Barrasso, 1980; Boitani 1982). Since wolves generally leave their retreat areas for foraging excursions during the night (Boitani, 1982; Urios et al., 1993; Vila et ul., 1993, this study), this is when use of open vegetative types increases.

Activity and movements

Indeed, home range and habitat use by wolves appeared strictly related to their activity. As reported for wolves living in similar conditions (Zimen, 1978; Boitani, 1982; Vila et al., 1995), wolf activity was essentially nocturnal and, by being complementary to human activity. allowed the wolves to visit and travel in areas intensively used by people. At night, we often spotted wolves while moving across the villages or crossing the main paved roads, and similar observations were reported by Zimen (1978) and Boitani (1986) for the Maiella region in Abruzzo. In North America, although some reports describe wolves being active mostly at night during summer (Murie, 1944; J o s h , 1966; Kolenosky & Johnston, 1967; Ballard et al., 1991), wolves have also been observed to be active during daytime in winter (Mech, 1970, 1977, 1992; Peterson et al., 1984). Vila et al. (1995) depicted a nocturnal die1 activity pattern with a tendency toward bimodality for wolves in Spain, and suggested that nocturnal habits might have evolved to minimize contacts with people. We believe this to be so for the wolves in our study area as well and suggest it represents an example of shift in the temporal niche due to human disturbance (Daan, 1981 ). This explains the high correlation between activity and distance travelled, as most of the activity involved daily round-trip travelling from retreat areas to traditional feeding sites found in the outer portion of the home range. Around onset and cessation times, however, overall activity did not necessarily correspond to distance travelled. During these phases of the circadian activity, the wolves moved exclusively around their retreat areas where they could engage in some sort of social activity, as it has been observed elsewhere before and after hunting expeditions (e.g. Murie, 1944; Carbyn, 1974).

Start and endpoints of daily movements were limited in number and appeared highly traditional, further supporting the centrality in space use perceived by home-range analysis. The few exceptions involved the longest nocturnal movements, when the wolf was apparently forced by the approach of sunrise to retreat to occasional or less traditional resting sites (e.g. S3, see Fig. 2). Similar observations were also reported by Boitani (1986) for the wolves in the Maiella range, and underline the flexibility of wolf behaviour when living at close quarters with humans. Daily movement patterns involved an extensive use of the home range, coupled with traditional use of the retreat area, and supported what Zimen (1978) termed the ‘star-shaped’ movement for the wolves in the Maiella range. Although extensive use of the home range may, indeed, reflect the nature and distribution of food resources, expressions of territorial behaviour such as scent-marking (Peters & Mech, 1975) could have prompted the wolves to travel frequently throughout their entire home range. Nevertheless, the distance travelled per night appeared to be mostly a function of the distance from the retreat area to the traditional

816 P. CIUCCI E T A L .

feeding sites. The wolves appeared to cover these distances according to the inherent capability of the species, as the estimated rate of movement compares well with that reported for different ecological conditions in North America (2.4 km/h; Mech, 1970).

The lack of correlation between total distance travelled per night and the distance from successive daily relocations was to be expected on the basis of the cyclic nature of nocturnal movements (see Laundrk et al., 1987). For wolves living under conditions similar to those hereby reported, daily relocations do not provide an appropriate estimate of the total distance travelled per night. In this perspective, a sampling scheme that would allow for temporally independent radio locations (cf. Swihart & Slade, 1985) may not convey reliable measures and description of daily movements. Alternatively, sequential radio locations depict total distance travelled and may provide critical information on behaviour (see also Gese et al., 1990). For example, by sequential sampling Boitani (1986) recorded visits to sheep folds by wolves and their interactions with guard dogs, whereas we were able to estimate minimum time spent foraging at rubbish tips. In addition, sequential sampling may increase the accuracy of habitat use studies based on compositional analysis (Aebisher, Robertson & Kenward, 1993).

The wolves in our study area appeared to depend to a large extent on rubbish, as, on average, they visited more than one rubbish tip per nocturnal movement, foraging systematically and periodically in all rubbish tips within their home range. This might suggest that more than one rubbish tip was necessary to fulfil their energetic requirements or, alternatively, that the wolves feeding on rubbish did not eat all they could get but rather were quite selective, probably searching for the most nutritious and palatable items. Unlike what Zimen (1978: 282) suggested for the Maiella range, food availability at rubbish tips in our study area appeared not to interfere with pack cohesion: the S. Pellegrino pack comprised at least five individuals in winter and up to five wolves (adults and subadults) were observed travelling together in the proximity of traditional feeding sites in autumn. By following the adults during their nocturnal movements, the pups most probably learned the location of traditional feeding sites and the travel routes to reach them. The observed pack size and cohesion in our study area could also be consistent with the necessity actively to defend resources, as hypothesized by Macdonald & Can (1995) from the large groups of free-ranging dogs in the same area.

Since minimum time spent foraging at dump sites averaged about one hour per nocturnal movement, it is also possible that other food items were included in the wolves’ diet. In one out of 10 nocturnal movements (see Table lII), M05 did not reach any traditional feeding site but moved about in an area particularly rich in wild boar. Although no evidence of predation on wildlife was obtained from three years of snow-tracking data, and no wild boar kills andor remains were found during the study, we believe hunting or scavenging carrion could have complemented the diet to some extent. Even though we did not quantitatively assess the diet of resident wolves, quite often the scats recovered in the field were composed of wild boar remains, the only ungulate largely available in the study area.

Whether the location of traditional feeding sites dictated the use of a single retreat area or, alternatively, the scarce availability of optimal retreat areas interfered with the successful hunting of wild prey, can only be assessed by monitoring the spatial and feeding ecology of wolves in similar areas but under different ecological conditions (i.e. availability of wild prey and no rubbish tips). Meanwhile, as restocking of wild prey along with proper waste management have often been advocated as conservation priorities in wolf areas (e.g. Boitani, 1982; Boitani & Fabbri, 1983), habitat management interventions should be simultaneously contemplated to ensure availability of optimal retreat areas, especially in environments altered by human presence.

Financial and logistic support was provided by the National Institute of Wildlife Biology (X.N.F.S.), Bologna. One

MOVEMENTS AND ACTIVITY OF WOLVES IN CENTRAL ITALY 817

of us (FF) was the recipient of two grants from Earthwatch (Watertown, Mass.). Fabio Corsi helped with GIS analysis. K. Benvenuto, E. Schoenfeld, G. Talarico and other volunteer wildlife technicians provided helpful assistance in the field. An anonymous referee provided useful coinrnents 011 the manuscript.

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