suffolk’s harvest mice in focus - suffolkwildlifetrust.org · the overall aim of this project is...

Report to: PTES and The Chadacre Trust

Martha Meek

Suffolk Wildlife Trust

2009-2011

Suffolk’s Harvest

Mice in Focus

Credit: Terry Longley seeing.org.uk

1 Suffolk‟s Harvest Mice in Focus

Suffolk Wildlife Trust 2011

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4081 pellets were analysed from 226 sites

35% of the sites contained harvest mouse remains

Harvest mice were found to make up 1.5% of the barn owl’s

prey

Field visits found harvest mice nests at 85% of all sites where

they had been reported in owl pellets from that locality

Harvest mouse nests were also found at 74% of sites where

they had not been found in owl pellets from that area

Nests were found in a range of habitats including arable field

margins, rough grassland, riversides and other wetland sites

Of the ten different habitat types where nests were found, six

were associated with water/wetland

It was notable that harvest mice were found to be nesting in

wild bird/game cover crops, particularly those containing

millet

Connectivity in the landscape has more influence than habitat

type on the number of nests being found, with very well

connected sites having the highest number of nests per site

Well connected sites are often associated with estuaries, fens

and grazing marshes, where there is extensive areas of suitable

habitat

Harvest mice are widespread in Suffolk, only completely absent

in very intensively farmed landscapes with no tall grass

margins

Barn owls were only reliable in detecting harvest mice where

the pellet sample size was 40 or more

If good harvest mouse habitat can be identified, nest searching

is the preferable option for a surveyor

A predictive model for finding harvest mice nests has been

developed based on the findings of this study



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Introduction Pg. 3

The history of the harvest mouse in Britain

Past studies on harvest mice in East Anglia

Pellets as evidence of harvest mice

Project Aims

Methodology ` Pg. 6 Pellet collection

Pellet analysis

Site selection

Site visits

Data collection & analysis

Results Pg. 14 Results from pellet analysis

Results from site visits

Wild bird and game cover crops as harvest mouse habitat

Discussion Pg. 27 Using barn owls to find harvest mice

Searching for harvest mice nests

The harvest mouse and waterside habitat

The harvest mouse in a farmed landscape

Habitat connectivity is critical

Adapting to a modern farmed landscape

Managing habitat for harvest mice

Conclusion Pg. 36 The future for harvest mice in Suffolk

Conservation of the harvest mouse:

using what has been learnt for the future

Project limitations and variables

References Pg. 39

Appendix Pg. 41 Other project outcomes

Full data sets for figures 15-18

Acknowledgements

Pellet collection sheet

Pellet recording sheet

Nest search form

Map sample

Newsletters

General factsheet

Farmland factsheet

(no page numbers for items in italics)



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The history of the harvest mouse in Britain The harvest mouse Micromys minutus has always been associated with lowland arable

landscapes, commonly portrayed sitting on an ear of wheat. This image is so common

yet evidence now suggests it is far from true, with the harvest mouse more likely to be

found in a reedbed than a field of wheat.

The species was first described by the naturalist

Gilbert White in Hampshire in 1767, “From the

colour, shape, size and manner of nesting, I

make no doubt but that the species is

nondescript. They are much smaller and more

slender and have more of the squirrel or

dormouse colour. They never enter into houses;

are carried into ricks and barns with the

sheaves; abound in harvest, and build their nests

amidst the straws of the corn above the ground,

and sometimes in thistles.” (White, 1767).

Harvest Mice with nest in wheat as illustrated in 1900s Credit: George Abbey, 1909

The abundance of harvest mice at harvest time, as described by White, did not appear

to change until the 1950s. Many articles were written in the 1950s about harvest mice

overwintering in large numbers in straw stacks both in Hampshire and Oxford

(Southwick, 1956; Rowe, 1958; Rowe & Taylor, 1964). Anecdotal evidence from

Suffolk farmers who were working in the fields in the 1950s also suggest that it was

common to see harvest mice both in the field at harvest and in stacks at threshing

time.

It was not until the widespread introduction of the combine harvester in the

late 1950s, that major changes at harvest time were seen. Whole fields began to be

cleared in a matter of hours leaving no refuge for small mammals and straw stacks as

winter refuges were lost. The harvest mouse was no longer commonly seen at harvest

or threshing time and many believed it to be disappearing from our countryside. This

perceived decline and lack of surveying continued until 1973 when the Mammal

Society commissioned a detailed survey into the status and distribution of the harvest

mouse. Over 1000 individual records, mainly of breeding nests, were gathered. These

records were concentrated along the east coast, south of Yorkshire and across the

southern counties and the south coast, being more sparsely distributed in the west



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country. Records were very sparse in Wales and limited to a few scattered records in

Scotland. They were considered to be a common species in all of East and South

Britain (Harris, 1979).

This survey was repeated in 1996-97 to assess for changes in range, 300 of the

same 800 sites were visited but only 30% were found to contain harvest mouse nests

(Battersby, 2005). This evidence led to the harvest mouse being classified a

Biodiversity Action Plan Species due to the apparent 70% decline. A survey by

WildCRU at Oxford University also found a steep decline from 2004 to 2007 in

numbers of harvest mice in a lowland arable landscape in the Thames valley (Riorden

et al, 2007). Past studies suggest however, that harvest mice have cyclical populations

which could explain an apparent decline associated with studies conducted over a

shorter time interval (Trout, 1978; Harris, 1979).

Past studies on harvest mice in East Anglia In contrast to national studies, those carried out in East Anglia do not appear to find

an extreme decline in harvest mouse numbers. A short study in Suffolk in 1978 found

the harvest mouse to be widespread, present in all 10km squares within Suffolk and

furthermore, in three of those squares they were found to be common (Naunton,

1979). A national study on barn owl pellets, looking at changes in diet between 1974

and 1997 found that overall and in Eastern England harvest mice as a prey item

increased over this time period (Love et al, 2000).

Studies carried out by Perrow & Jordan and Perrow & Jowitt from 1992-2003

concentrated mainly on wetlands in East Anglia where they found the harvest mouse

to be abundant. They suggested that wetlands may be providing a stronghold for

harvest mice in East Anglia whilst local extinctions may have occurred in arable

farmland where habitat has been lost to intensification (Perrow & Jordan, 1992.

Perrow & Jowitt, 1993; 1995; 2003).

Recent informal studies in Essex and Bedfordshire have also found the harvest

mouse to be widespread in suitable habitat, especially roadside verges in Essex and

reed canary grass in Bedfordshire (Dobson; Woolnough; personal communication).

From 1980 to 2008 records of harvest mice in Suffolk were widespread (figure

1) but this was over a very long time period.



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Figure 1: Historic records of harvest mice and nests in Suffolk

(∆- years 2000 to 2008, О- years 1980 to 1999)

This map shows all historic records of harvest mice and nests as collected

by the Suffolk Biological Records Centre from 1980 to 2008

Pellets as evidence of harvest mice The success of the Suffolk Community Barn Owl Project combined with the lack of

knowledge on harvest mice in Suffolk gave the perfect opportunity to study harvest

mice using barn owl pellets. Barn owls in Suffolk have steadily been increasing in

numbers and spreading to new parts of Suffolk. This range expansion has been helped

by the erection of over 1000 new nest boxes combined with the creation of new rough

grassland hunting ground, much being arable field margins.

As barn owls produce pellets they provide the perfect way to study small

mammal communities as the remains of mammal skulls and jaws within them can be

easily identified. This expansion in the barn owls range provided the perfect

opportunity to collect pellets from across Suffolk and analyse them for the presence of

harvest mice. Past work on owl pellets has shown that barn owls do prey on harvest

mice regularly, being found in pellets from approximately 50% of sites from eastern

counties (Glue, 1975). Overall they tend to make up less than 1% of the barn owls

diet, showing that the barn owl does not have a big impact on harvest mouse

populations (Glue, 1975). They are also a good species to use in mammal studies as

barn owls are habitual and frequent the same roost sites for many years making

collection of the pellets an easy task (Glue, 1970).

Project Aims The overall aim of this project is to find out if barn owl pellets are an effective way to

study harvest mice. This will be backed up by extensive field studies to search for

nests. The nest searches will also enable a detailed study of the harvest mouse in the

county of Suffolk to be carried out, including distribution and habitat preferences.

The practical outcome of the project is to provide a conservation monitoring tool and

information on effective habitat management for the harvest mouse which can then be

used in other parts of the UK.



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Pellet collection Pellets were collected by volunteers monitoring barn owl boxes and nesting sites

across Suffolk over the summers of 2009 and 2010. Collection was begun in 2009 as

this was known to be a year with low field vole numbers. This small mammal is the

barn owls preferred prey and they exhibit cyclical changes in population sizes. It was

thought that a lack of field voles may force the barn owls to prey on a wider range of

species, making harvest mice more likely prey items.

As most monitoring visits take place in June, most of the pellets for the project

were collected in June although some were collected later and some sites re-visited in

autumn. Fresh pellets were collected wherever possible, but in some cases older

pellets of unknown age were collected. Twenty or more pellets were collected from

each site but in some cases the sample was smaller. For each site details were

recorded including the date of collection, six figure grid reference, male or female owl

roost, age of pellets, site name, habitat description and site of roost (see appendix for

pellet collection sheet).

Pellet analysis Pellets were analysed by trained volunteers (a total of 72 current barn owl monitors

and 52 new volunteers trained at 5 training days) and all the species were recorded by

presence of skulls and jawbones (see appendix for pellet recording sheet). Once a

sample was finished the skulls and jaws were bagged and labelled and returned for

verification to ensure nothing was missed or incorrectly identified. To ensure

volunteers were not leaving anything in the pellet debris, a number of random samples

were checked and nothing was found. In feeding experiments with captive barn owls,

skulls and jawbones have been found to be very effective at calculating the correct

numbers and species of prey items (Buckley & Goldsmith, 1975).

Pellet analysis training day



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Site selection Sites were split into two categories, those where samples of owl pellets had harvest

mouse remains (76 sites) and those where harvest mouse remains were absent (147

sites). Site visits were undertaken on 95 sites. Of these 49 were positive for harvest

mice in owl pellets and 46 were negative for harvest mice in owl pellets. This

represents approximately 50% of fieldwork in each category, in order to test the

theory that barn owls can be used as a tool to locate harvest mice on the ground.

The sites were selected to represent a good geographical spread across

Suffolk. This method did have its limitations as barn owls are concentrated to the east

side of Suffolk with a marked lack of breeding sites across the west of the county.

There are also more concentrated populations of barn owls to the north of the county

along the Waveney valley (figure 2). This gives the project a geographical bias to

these parts of the county.

Figure 2: Barn owl boxes in Suffolk

Over 1000 barn owl boxes have been erected in Suffolk, all in areas containing habitat

suitable for breeding barn owls. Approximately 10% of the boxes are used by

breeding barn owls.



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Site visits All sites were visited across a two year period from October through to March when

harvest mouse nests are at their easiest to find. The boundaries of the land visited

were defined by the land ownership and varied in size from gardens to large arable

businesses. Once on site, the areas to search were chosen based on their suitability for

harvest mice. Suitable habitat included grassland left to grow long for approximately

three years including field margins, wet areas of any kind with long vegetation present

and wild bird/game cover plots. On sites where more than one habitat was present

each suitable habitat type was searched. The time searching each area within a site

was recorded along with the time taken to find each nest. All areas searched were

marked on a map and a grid reference taken for each nest found. The search time was

often limited by the size of the habitat block but where it was not, searching time was

for approximately 30 minutes. Details were recorded for each nest including the plant

species it was found in and the height above ground (see appendix for nest search

form and map sample).

Nest searching in long grasses Harvest mouse nest

Data collection & analysis To interpret the field data all sites visited for nest searches were allocated an overall

site habitat type plus a connectivity score. This enabled the differences in numbers of

harvest mice nests at different sites to be looked at in relation to the surrounding

habitats and landscape. Each individual nest was then allocated a habitat type within

the site to look at specific nesting preferences within the wider landscape.

The classifications used are below, including definitions and photographic

illustrations:



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Overall site habitat type: defined as the site where the search took place and the

immediate surroundings as seen.

1. Arable with or without associated field

margins

2. Arable with significant amounts of dry

grassland that are not field margins

3. Arable with associated river valley

4. Lowland wetland – grazing marsh,

fenland and estuary



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Connectivity score (refers to approximately 1km radius of site):

1. ‘Very well connected’ includes:

Sites near lowland rivers with

associated habitat

Estuarine sites with associated

habitat

Extensive fenland/grazing

marsh/rough grassland

Farms with very well

connected, tall margins

throughout



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2. ‘Some connectivity’ includes:

Sites near rivers where

associated habitat is patchy or

not present (normally closer

to rivers source)

Arable sites with some tall

margins

3. ‘Very poorly connected’ includes:

Arable sites with no tall

margins and no suitable

habitat within sight or

connected in any way by

suitable habitat

Suitable habitat refers to long grass where it is uncut for 2-3+ years or habitat

associated with water e.g. reedbeds, ditch vegetation such as reed canary grass etc. It

does not include hedges where surrounding vegetation is very short.



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Habitat types for individual nests:

1. Arable field margin/corner/ditch

(dry or seasonal)

2. Wild bird/game cover crop

3. Rough grassland (where not bordering

arable)

4. Tree plantation (where grass is created

by plantation)

5. Grazing marsh and grazed dykes



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6. Rivers edge and permanent wet ditch

including ungrazed dykes

7. Fen

8. Reed bed – Phragmites dominated

(wet and dry)

9. Pond edge

10. Estuarine edge



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4

5

6

7

8

9

0

6 7 8 9 0 1 2 3 4 5

Pellet records

negativepositive

Results from pellet analysis

The overall numbers of sites from which pellets were collected was 226.

76 of these sites had pellets collected with harvest mouse remains present and 147

sites had no evidence of harvest mice in the pellets.

In total 4007 pellets were analysed from 226 different sites

36% of these sites had evidence of harvest mice in the pellets

The number of pellets containing harvest mice was 183

The total number of prey items was 16,481

266 of the total prey items were harvest mice

The overall percentage of harvest mice as prey items was 1.4%

The overall percentage of harvest mice in large samples (20 pellets

or more) was 1.5%

The average number of prey items per pellet was 4.1

Figure 3: All sites where pellets were collected (red are sites where pellets were

positive for harvest mice and blue were negative)

Figure 3 shows all the sites where pellets were collected and the main rivers and

tributaries. The percentage of pellet collection sites on the map associated with rivers



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is 75% where pellets were positive for harvest mice and 71% where they were

negative. The areas pellets were collected from were biased by the collectors some of

whom visited more sites than others. The Waveney Valley in the northeast is the area

where most pellets were collected, although it is also the area with the highest

concentration of breeding barn owls. The west of Suffolk does not support many barn

owls so few records came from that area. The east coast was unfortunately under-

represented due to poor pellet collection rates.

Table 1: Frequency of Occurence of Harvest Mouse Remains in Pellet Samples -

overview and comparison of this study with others

Study Location Number of

Pellets

Sampled

Number

of Sites

Average no.

pellets

analysed

per site

Harvest

Mice

(number)

% Harvest

Mice as Prey

Items

Proportion of

Sites/Diets

where HM

found

Glue, 1975 Eastern

England

ca. 2338 25 93 92 1.1 56%

Buckley &

Goldsmith,

1975

East Norfolk 5357 25 214 (14-

1271)

519 3.2

(range= 0.1-

6.6)

88%

Love et al,

2000

National,

1974 data

6353 143 44 143 1.4 Data not

available

ibid National,

1997 data

13,562 81 167 1146 2.3 “

ibid Eastern

England,

1974 data

923 8 115 10 0.3 “

ibid Eastern

England,

1997 data

8364 32 261 909 2.9 “

SWT,

2008/11

Suffolk

(large

samples

only)

2987 99 30 173 1.5 53%

ibid Suffolk

(all data)

4007 226 18 266 1.4 36%

Table 1 gives an overview of owl pellet studies, comparing harvest mice in barn owl

pellets from 1975 to the current study. Most studies were carried out in East Anglia

although some national data is included. There are large variations in the total

numbers of pellets sampled, the number of sites they were collected from and the

average number of pellets analysed per site. The data does not show large variations

according to the location and the year. What it does show is that the probability of

finding harvest mice remains in pellets increases with the number of sites and the

number of pellets analysed per site.



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Comparison of numbers of species found in owl pellets

Figure 4: Numbers of species found in all owl pellets

The numbers of species

shows the field vole to be

the most important prey

item both in numbers and

as prey units (see below).

Other species most

commonly preyed upon in

descending order are the

common shrew (26%),

wood mouse (12%),

pygmy shrew (8%) and

bank vole (6%). The

harvest mouse makes up

only 2% of prey items.

Figure 5: Numbers of species in all owl pellets as prey units

(calculated by average weight of species as taken from Yalden, 2003)

When comparing prey

units, some of the

larger species such as

rat and water vole

become more valuable

as prey to the barn owl

and species such as

the pygmy shrew less

important due to its

small size. The

harvest mouse as a

prey unit also drops to

1% due to its small

size.



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Harvest mice relating to small mammal species diversity

Figure 6: Number of species recovered in samples of 20 pellets from sites with

and without harvest mice present (red-samples with no harvest mice in pellets,

blue-samples with harvest mice in pellets)

This histogram does show two populations and suggests that the where harvest mice

are present small mammal species diversity may be higher. A 2 tailed t-test run on the

data is significant but only to a very low p-value (1.72).

Minimum owl pellet sample size

What is the minimum pellet sample size needed to find harvest mice?

The following figures are best estimates based on all the data:

19-20 pellets would find 50% of all sites with harvest mice

35-40 pellets would find 85% of all sites with harvest mice

The figures are based on mean and median numbers of harvest mice per numbers of

pellets of different sample sizes. Confidence limits are based on the assumption that

the variation in numbers of harvest mice across sites has a normal distribution.

Predictions are based on harvest mice being present at 79% of all sites as found

during site visits.



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Results from site visits

Site visits were carried out from October through until March in the years 2009-11 to

sites where owl pellets had been collected. The aim was to search for evidence of

harvest mice on the ground by finding the distinctive woven nests. In total 95

different sites were visited, 49 to sites where the pellets collected had been positive

for harvest mouse remains and 46 to sites where the pellets were negative for harvest

mice. Nests were found at 86% of „positive‟ sites and 72% of „negative‟ sites.

Figure 7: Map of Suffolk showing all 95 site visits carried out - red are visits to

‘positive’ sites and blue visits to ‘negative’ sites

The sites chosen were based on their geography, although limited by distribution of

barn owl boxes which are fewer in the West. The aim was to ensure a good

representation of both positive and negative sites across the county of Suffolk.



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Figure 8: All harvest mouse records (plotted as 1km2)

Figure 8 shows all records for the project from Spring 2009-Spring 2011 plus all the

main rivers and tributaries. The records include all breeding nests and non-breeding

nests recorded from site visits. They also include some verified records of live mice

and dead mice as sent in by members of the public. Records from owl pellets are not

included as they can be from a wider area of up to 2km radius, or more in winter,

from the pellet collection site. For all the records on the map 73% are associated with

the main rivers and tributaries.



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Overall percentage of sites where harvest mouse nests were found

Figure 9: Percentage of ‘positive’ pellet sites visited where nests were found

Figure 10: Percentage of ‘negative’ pellet sites visited where nests were found

Harvest mouse nests were found at 86% of all sites where the pellets collected were

positive for harvest mouse remains and 72% where the pellets were „negative‟. The

percentage of sites where nests were found was 14% higher at sites where the pellets

collected were „positive‟.



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Nests related to pellets and search time

Figure 11: Number of harvest mice recovered in samples of 20

or more pellets vs. nests found at 45 sites

The majority of samples of pellets (range 20-126 pellets) contain the remains of

between one and five harvest mice and the majority of sites have less then ten nests.

The calculated correlation coefficient is 0.163 which means only 3% of the two

variables are in common with each other giving no significant relationship between

the number of harvest mice in pellets and the number of nests found. There is still no

statistically significant relationship even when all outliers and samples with under 40

pellets are removed (correlation coefficient 0.317 = 10% of the two variables are in

common).

Figure 12: Number of nests vs. time to find first nest in 74 areas at 46 sites

At the majority of sites it took less than ten minutes to find the first nest and in all

sites apart from one, less then 10 nests were found, with most sites having less than

five nests. The correlation coefficient is low, -0.154 (2% in common) giving no

statistically significant relationship between search time and numbers of nests found.



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Nests found by habitat type Figure 13: Number of nests found in each habitat type

The overall numbers of nests found was highest in arable field margin/corner/ditch,

wild bird/game cover, rough grassland and rivers edge/wet ditch. The lowest numbers

were found in fen, followed by estuarine edge and pond edge.

Figure 14: Ratio of nests found in each habitat type to the number

of sites where each habitat occurred

Figure 14 corrects for the numbers of nests in relation to how many sites were

searched containing each habitat type, this then shows which habitats are most likely

to contain nests. Wild bird/game cover has the highest numbers of nests, an average of

4.5 per site. Tree plantations also have significantly higher numbers of nests at 2.8 per

site whilst all other habitats have an average of only 1-2 nests per site.



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Number of harvest mouse nests related to habitat classification

Figure 15: Percentage of sites where nests were found for different site habitat

classifications

Nests were found at 65% of habitats classified as arable (1) and arable with grass (2).

This figure rose to 85% for arable with river valley (3) and 100% for lowland wetland

habitats (4).

Figure 16: Nest per site ratio for the different site habitat classifications

Once nest numbers had been corrected for the number of sites the habitat containing

most nests per site was lowland wetland with 5.25 nests (4). This dropped to 3.75

nests for arable (1), 3.0 nests for arable with river (3) and 2.75 nests for arable with

grass (2).

1: Arable

2: Arable with grass

3: Arable with river valley

4: Lowland wetland: grazing

marsh, fenland and

estuary



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Number of harvest mouse nests related to site connectivity

Figure 17: percentage of sites where nests were found for different connectivity

scores

Nests were found at 100% of very well connected sites (1), 85% of sites with some

connectivity (2) and only 40% of sites that were very poorly connected (3).

Figure 18: Nest per site ratio for the sites with different connectivity scores

Very well connected sites (1) had the highest numbers of nests per site at 5.25, sites

with some connectivity (2) had 2.5 nests per site and very poorly connected sites (3)

had 1.75 nests per site.

(see appendix for full data sets from figures 15 to 18)

1: Very well connected

2: Some connectivity

3: Very poorly connected



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Number of nests and connectivity

The numbers of nests in arable margins and rough grassland were found to be

related to connectivity: (here connectivity refers to the quality of the habitat as there

were no other habitat types present e.g. river valleys, to create corridors for

movement). In very poorly connected habitats a mean average of one nest was found

in arable/grass habitat (based on four sites). In better connected habitats the mean

average number of nests in arable/grass rose to 2.75 (based on 24 sites) and in very

well connected arable/grass habitats this mean average increased to 8.25 nests (based

on four sites). Median scores respectively were 1, 3 & 5.5 nests.

The numbers of nests in poorly connected habitat were found to increase where a

good food source was present: At the eight sites where harvest mouse nests were

found in isolated patches of habitat ranging from 1200m2 to 13950m

2, there was a

marked difference in number of nests depending on habitat type. In the margins and

rough grass habitats an average of one nest was found across four sites. In the areas

with a good food source present including wild bird/game cover crops and a soft fruit

plantation an average of 6.25 nests was found across four sites.

Wild bird and game cover crops as harvest mouse habitat

Wild bird and game cover crops have been found to support good numbers of harvest

mice where they contain the right mixture of plant species. Below is a summary of

what was found:

In total 15 areas of wild bird/game cover crop were searched

Nine out of the 15 wild bird/game cover crops searched contained harvest

mouse nests

Four sites had harvest mouse nests only in the wild bird/game cover crop

Four of the wild bird/game cover crops that did not contain harvest mouse

nests contained only maize

Two of the wild bird/game cover crops that did not contain harvest mouse

nests were mixed plant species including millet but had been stunted by dry

weather and were very short

One site that had 15 harvest mouse nests in a crop of reed millet and white

millet was very poorly connected and had only a small area of rough grass

adjacent where no nests were found

Eight of the nine wild bird/game cover crops with harvest mouse nests

contained millet of some variety although the crops with most nests had at

least two varieties of millet

Other plant species that were found supporting harvest mouse nests and

presumably providing a food source were quinoa and triticale

Sunflower and kale were also present in wild bird/game cover crops but were

not seen to support harvest mouse nests

Most wild bird/game cover crops used maize as a supporting plant species



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Figure 19: The average number of nests in different plant species as found in the

15 plots of wild bird/game cover crops

Plots containing more than one variety of millet (reed, white and red) contained

significantly more nests than plots containing only one variety of millet. Plots with a

mix of other species had low numbers of nests and those with only maize had no

nests.

Nest in game cover crop of reed Close up of nest in a millet spray in

millet and white millet a wild bird and game cover crop



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Using barn owls to find harvest mice Barn owls have been used as a tool for studying small mammal populations

for in many studies, significant for both looking at the diet of the barn owl and the

mammals themselves. Past studies have looked at harvest mice as barn owl prey and

found them in 50% of diets from southern and eastern counties (Glue, 1975), but have

not attempted to back this up with field visits to look at the effectiveness of barn owls

as monitors of small mammal populations.

The aim of this study was to follow up the pellet analysis with site visits to

search for harvest mouse nests, using the results to look for a relationship between the

two and the overall effectiveness of the method for surveying the harvest mouse. No

trapping was carried out, only nest searches, so it has been assumed throughout the

study that there is a positive relationship between the number of nests found and the

number of mice.

Other studies have found both that there is no relationship between population

and numbers of nests (Riorden et al, 2009) and that there is a very good relationship

(Kuroe et al, 2011). This contrast is most likely due to the very low numbers of mice

trapped in Riordens study which can make results difficult to interpret.

In order to test the theory that barn owls are a good tool for finding harvest

mice, half the sites visited were where pellets had been negative for harvest mice and

half were positive. The theory was not proved as nests were found at 72% of negative

sites and 86% of positive sites (figures 9 & 10). The fact that visits to positive sites

yielded 14% more sites with harvest mouse nests does show that in some cases the

barn owls were effective as monitors of harvest mice. Visits to sites where barn owls

were present but there was no suitable habitat for harvest mice are evidence of this.

This site is managed for barn owls to encourage field voles but the

grass is not long enough to support breeding harvest mice which

were not present here or in the owl pellets collected



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Overall in Suffolk barn owls and harvest mice were found to have very similar

habitats. Although the specific habitat requirements are different the landscapes used

by both species are very similar. Small mammal diversity was also found to be higher

in pellet samples where harvest mice were present (figure 6) showing that the harvest

mouse may be a good indicator species for the health of the habitat and its capacity to

support other species.

As stated on page 17 the minimum pellet sample size in order to be confident

in finding 50% of all sites is 19-20, rising to 35-40 to be confident in finding 85% of

all sites. This means that the method could be used with much more confidence if the

sample size could be increased to 40+ for all sites. This does raise questions of the

practical application as the time taken to analyse the pellets would increase and in

many cases it would be very hard to collect that number of pellets from one site.

As the average pellet sample size was only 18 in this study (see table 1),

knowing that 35-40 pellets would find 85% of sites, the proportion of sites positive

for harvest mice remains in pellets would have risen if the average sample size was

larger.

Searching for harvest mouse nests Although nest searching may be thought of a very time consuming process, in

reality a good surveyor can assess habitats very quickly and only search those areas

that are likely to contain nests. The nests are very distinctive and are rarely confused

with other small mammal nests so little training is needed in recognition.

In this study ground nests were not recorded as field voles commonly build

these type of nests, although other studies have found that harvest mice do build

ground nests in winter (Ishiwaka et al, 2010) and also when disturbed as second

breeding nests (Trout, 1978). One other type of nest which was not recorded but was

found on a few occasions was a tubular shelter often incorporating leaves and always

found about 1m off the ground.

Ground nest – unrecorded in this project Tubular shelter nest – unknown species

It was thought that there may be a relationship between the time taken to find

the first nest and the overall number of nests found. Figure 12 disproves this theory,

meaning no assumptions can be made on total numbers of nests even if the first nest is

found within a short time. The number of harvest mouse skulls and jaws in the pellets

was also found to have no relationship with the number of nests found on the ground

(figure 11). This means that numbers of skulls in pellets cannot be used to assess the



Report to PTES.

size of harvest mice populations. Both these factors make site visits to carry out nest

searches invaluable in assessing harvest mouse populations.

Nest searches are best carried out from October through until March. Any

searches before October will probably result in the disturbance of breeding mice,

although it is likely that mice will be breeding until December if the weather is mild.

In this study current breeding nests with live young and adult females were seen until

November.

Nest searches in reed beds and on river banks should be carried out before

January as any later than that they will probably have been knocked from the reeds by

bad weather or the vegetation may have been flattened by winter floods. Nest searches

in grasses can continue until the vegetation starts to grow in April and obscure them

from sight. Nests in dry grasses can persist for over a year as demonstrated by a nest

monitored from autumn 2009 to autumn 2010 when it was still easily recognised as a

harvest mouse nest. Knowing this it should also be taken into account that the

previous years nests may be found alongside the current years nests in dry grassland.

Harvest mouse nest in dry grassland approximately

one year after it was first found in October

Although site visits are very valuable owl pellets should not be ruled out as a

method for finding harvest mice. In this study half of the sites were pinpointed using

owl pellets and the other half the simple presence of barn owls, which would be a

good starting point for finding harvest mice in itself as they often share the same

habitats. Certainly in a landscape where harvest mice populations were very scattered

barn owl pellets may be a very useful tool in finding them.

The harvest mouse and waterside habitats The harvest mouse was found to be widely distributed across the county of

Suffolk, with nests overall at 79% of all the 95 sites searched. The records are widely

distributed across Suffolk with no area having an obvious lack of records (figure 8).

73% of the sites are closely associated with rivers (within 1km), even if the

actual habitat they were found in was not riparian. This figure is the same for barn

owls based on the pellets collected, suggesting that both species are more likely to be

found near a river valley.

River valleys are often considered as marginal farming ground as they can be

hard to drain so therefore very waterlogged and can also be steeply sloped making



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access by modern machinery difficult. For this reason they are often grazed and are

sometimes managed for nature conservation creating wildlife habitats and corridors

for movement in the process. There is also a legal obligation by farmers to avoid

spaying any chemicals close to a water course (including smaller streams and

tributaries) which can then lead to an increase in the diversity of plant and

invertebrate species.

The habitat classification with the greatest likelihood of finding high numbers

of harvest mice nests was lowland wetland (figures 15 & 16). Lowland wetlands

including fens, grazing marshes and estuaries are more extensive habitats than many

river corridors, which are ideal for movement but may not contain enough good

habitat for harvest mice to successfully breed.

Of the ten habitat types that nests were found in, six are associated with water.

Of these habitats the likelihood of finding nests is highest in fens, reed beds and

estuarine edges (figure 14). These are the habitats most likely to contain extensive

amounts of suitable vegetation for nest building. Grazing marshes where cattle have

access to all areas including the ditches support less breeding harvest mice as they

often contain little suitable habitat.

This grazing marsh has unfenced ditches and high grazing pressure

from cattle, meaning that the ditch vegetation is kept short and therefore

unsuitable for breeding harvest mice



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Pond edges, river edges and wet ditches support less harvest mice overall (figure 14)

as they can be isolated and are not always part of a well connected landscape. This is

varied though as river edges in this study sometimes provided a narrow corridor only

suitable for movement and sometimes very extensive habitat for breeding.

Here the deep set river had a

narrow strip of rough

grassland along its banks,

ideal for movement and

dispersal to new areas by the

harvest mouse. It also

supported a very small

breeding population,

constrained by regular cutting

and flooding. The

surrounding farmland had a

network of tall margins but

they were cut too regularly

for breeding harvest mice.

This river which had a

shallower channel provided

very extensive habitat because

of the way it was managed-

here primarily for pheasant

shooting but also for wildlife.

Wetland vegetation gave way

naturally to rough grassland

and the area supported a very

good population of breeding

harvest mice. In contrast to

the above site the surrounding

farmland was very intensively

managed with no tall grass

margins.

The higher numbers of nests found in wetland habitats, many of which have remained

unchanged for centuries, suggests that harvest mice in lowland arable landscapes have

always had stable „core‟ populations in wetland habitats. Perrow & Jowitt 1995, came

to the same conclusion after carrying out detailed studies on harvest mice in the

Norfolk Broads. These wetland populations may have prevented the loss of the

species from many areas of Suffolk as agriculture intensified over the last century.



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The harvest mouse in a farmed landscape The two habitat types which support the smallest numbers of harvest mice are

the arable field margins and rough grassland (figures 13 & 14). These are both

common habitats but are very varied in quality, easily lost due to cutting and often

isolated within farms.

The normal margin/rough grass cutting regime for farms within

Environmental Stewardship is a three year rotation, although a two year rotation is

also widely used. Three years growth is the minimum to support a good population of

harvest mice, as only in a few isolated cases were nests found in grasses that had been

uncut for two years. As cutting is often carried out in autumn or early winter in the

third year of growth, these rough grassland habitats are being removed as they

become suitable, often whilst the mice are still breeding. As cutting is rotational the

mice will always have somewhere to retreat to but will be unable to build up large

populations.

It is probable that due to chemical use in the crops that insect numbers are

depleted as a food source in most arable field margin habitats. Grass seeds may also

be low as a food supply in grass margins, especially if they are are cut before winter

when they are needed to sustain overwintering populations of harvest mice, which

have very high mortality over winter and early spring (Perrow & Jowitt, 1995; Haberl

& Krystufek, 2003). This lack of winter food and loss of suitable breeding habitat at a

critical point explains the persistence of only small populations of harvest mice in

rough grassland and field margins.

The exception to this is the small numbers of farms visited where the

management of margins was carried out in such an ideal way for harvest mice that it

created a network of habitat throughout the farm, which leads onto the importance of

connectivity for the harvest mouse.

Here beetle banks which supported good numbers of harvest mice contributed

to this farms network of exceptionally high quality margins managed for

wildlife conservation. Bence et al, 2003 also found beetle banks to contain

significant numbers of harvest mouse nests.



Report to PTES.

Habitat connectivity is critical Connectivity of habitat is one of the most important factors for the persistence

of good populations of breeding harvest mice. The management of margins to

increase connectivity within a farm was found to increase the size of harvest mouse

populations from an average of one nest on poorly connected farms to eight nests on

very well connected farms (see page 25). This demonstrates that not only is the

quality of the habitat important but also that increased capacity for movement within

sites increases numbers of harvest mice.

Connectivity has more effect overall than habitat type on nest numbers, as the

number of nests and chance of finding a nest rises steeply with good connectivity and

falls rapidly as connectivity decreases (figures 17 & 18). This shows how important it

is to reduce fragmentation of habitat which is considered to be one of the major

threats to biodiversity. A specific example in this study was a standard arable field

margin where a significantly higher than usual number of nests was found. The

habitat in the margin was not of a higher quality than usual but was well connected to

the Deben estuary by a stream containing reedbeds and fringed by rough grass. This

had allowed the mice to migrate from the fringes of the estuary to the field margin.

The margin in this picture contained a very high number of harvest mouse

nests as it was well connected to the Deben Estuary where harvest mice were

breeding successfully in the associated salt marsh and rough grassland.

An aerial view of the Deben Estuary showing the location of the margin in the

picture above (Image Credit Google Earth, 2010).



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A study carried out in Japan by Kuroe et al, 2011, also found that the size of

harvest mouse populations is determined by the connectivity of the habitat as well as

the quality. It proved that the loss of adjacent habitat lowers population size even if

the monitored habitat itself did not change.

With the introduction of Environmental Stewardship many farms have

reinstated long field margins which have allowed harvest mice to migrate from core

riparian populations into the wider arable landscape. It may be the case that harvest

mice did undergo a dramatic decline in Suffolk since the 1970s and that in recent

years the population has recovered as arable landscapes have become more habitable,

although this cannot be proven.

Harvest mice are known to be rapid colonisers of new habitat as shown by

their preference for newly planted woodlands. After wild bird/game cover, tree

plantations were the second most likely habitat type in which to find harvest mice

nests (figure 14). A study by Moore et al, 2003, also showed that harvest mice are the

most frequently trapped small mammal species in new farm woodland, using the long

grasses for nesting.

Harvest mice are mobile creatures and although they do not range more than

about 15-20m when foraging (Harris, 1979) they are capable of travelling easily over

50m through suitable corridors into new habitats (Perrow & Jowitt, 1995), although

this distance may decrease if the corridor through which they are moving is not of

good quality (Kuroe et al, 2011).

The timing of migrating young is not known but September and October

coincides with the movement of mice into winter habitat as studied in Finland,

brought about by the onset of the first frosts and halted once cold weather sets in

(Harris, 1979).

Adapting to a modern farmed landscape Harvest mice are very adaptable species and are generalists in that they are not

dependent upon any particular plant species. The most important feature of the

vegetation for harvest mice breeding success is the structure. In this study cocksfoot

grass, common reed, reed canary grass, reed sweet grass and other upright grasses

including false oat grass were the most commonly used plants for nest building. These

species are all capable of forming dense cover with a supporting stem structure, both

supporting the nest and protecting it from predation and bad weather. The other thing

these plants have in common is a wide leaf blade, ideal for splitting and weaving into

the nest. The position of the nest varies with the plant species, nests are found low to

the ground in dry grasses and over 1m off the ground in reeds and other reed like

plants.

Another plant which has the correct structure for nest building, plus a good

food source is millet, planted in recent years as part of wild bird and game cover plots.

Wild bird/game cover is the most likely habitat type in which to find high numbers of

nests (figure 14). Millet can be planted very densely and has a very supportive

structure with wide leaf blades, similar to reed canary grass which is a common native

plant in which to find harvest mouse nests. In the wild bird/game cover crops, the

likelihood of finding high numbers of nests increased with the presence of more than

one type of millet in the crops. The plot which contained the highest number of nests

was a game cover plot for pheasant shooting containing both reed millet and white

millet. It was a very poorly connected site with only a small area of rough grassland

adjacent and all field margins and hedges were cut very short.



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This game cover crop supported high numbers of breeding harvest mice within a

very intensively farmed arable landscape

It is possible that the mice had persisted in the rough grassland in low numbers

allowing them to migrate to the cover plot and build up in numbers over the summer,

or it is also possible that they had migrated to the area from a population elsewhere.

As the plot would not have been sown until May or reached full height until mid–

summer and the original number of colonisers was likely to be low, then the

population must have grown rapidly. Food supplies from cover plots, which are not

ploughed until spring, will also increase winter survival rates in harvest mice,

increasing breeding success in summer.

In this study millet was just as likely to be planted as part of a game cover plot

as a wild bird cover plot, showing that management for shooting as well as farmland

bird conservation can have very beneficial impacts on harvest mice populations.

Managing habitat for harvest mice As a generalist species harvest mice do not require specialist or complicated habitat

management. In general if a good network of habitats, in the form of tall grasses and

wetland vegetation can be provided year round and if harvest mice have some way of

reaching this habitat, they will probably begin to breed there. The breeding success

can then be raised by providing good winter cover and good sources of food, the most

obvious source of this being a wild bird/game cover crop including at least two

varieties of millet. Obviously management is dependent upon the habitat and this

detailed information can be found in the factsheets included in the appendix.



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The future for harvest mice in Suffolk

Harvest mice are widespread in Suffolk, only completely absent when searched for in

very intensively farmed landscapes with no tall grass margins. They have been found

in isolated grass habitats in low numbers and in isolated wild bird and game cover

crops in high numbers. Where habitat is both of good quality and well connected then

they are almost certain to be present. Only at some sites were the nests not found

where the habitat was good, these were all in very badly connected landscapes

showing the importance of connectivity.

Although harvest mice are widespread they are not always common, in many

cases only one or two nests were found suggesting that populations are able to persist

only at low numbers where conditions are not ideal. In this study over ten nests at one

site was seen as exceptionally good numbers but in the 1950s in Britain and in other

countries such as Russia, finding 100s of nests or live animals in straw stacks was not

uncommon (Trout, 1978). As surveys were not carried out until the 1970s it will never

be known how drastically numbers have dropped but it is probable that it is significant

due to drastic changes in our farmed landscape.

Although numbers may not be as high as they once were the future for harvest

mice in Suffolk looks to be secure. They are found on every major river in Suffolk

and appear to be moving easily out into surrounding farmland as habitat becomes

available. This network of lowland rivers will secure the future of harvest mice even

if farming practices in some areas make the landscape inhospitable and with the

increase of the use of wild bird and game cover crops harvest mice breeding and

overwintering success will increase.

Conservation of the harvest mouse:

Using what has been learnt for the future This study has demonstrated that the harvest mouse can be found using barn owl

pellets but that the presence of barn owls is enough without the pellets to initiate a

nest search in the area. If pellets are used then the minimum number to be sure of

finding 85% of sites with harvest mice is 40 pellets. This is a high number and very

time consuming to analyse, with each pellet taking up to an hour for new volunteers.

Where this method may be very useful is if harvest mouse populations are suspected

to be very scattered in small clusters and difficult to find on the ground.

A good starting point for any harvest mouse nest survey would be to identify

areas of good habitat and then visit with a good nest surveyor who would normally be

able to find a nest within approximately 10 minutes in good habitat. The likelihood of

finding harvest mice nests in the different habitat types is illustrated below as a

predictive model. If all the features in any one box can be seen at a site than the

likelihood of finding harvest mice nests is very high.



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Harvest Mouse Habitat Predictive Model

The area is associated with water

River edge, wet ditch, pond edge,

estuary, fen, grazing marsh with

fenced ditches

It has some connection to other suitable habitat

Vegetation has at least one year‟s growth

and is at least 1m high (if fallen in bad weather

Look for original standing height)

There are dense stands of vegetation present

Plant species present include common reed,

reed canary grass, reed sweet grass

The area is not associated with water

Rough grass is present: may be a rough meadow,

arable field margin or corner, dry ditch, road verge

It has good connection to other suitable habitat

The rough grass has at least 3 years growth

There are dense tussocks of vegetation present

Plant species include cocksfoot grass or other dense

tussock forming species

No rough grass present

A crop of wild bird or game cover mix is present

Contains one or more varieties of densely planted

millet and is over 1m high

VERY HIGH LIKELIHOOD OF

FINDING HARVEST MOUSE NESTS

No

No

Yes



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Managing habitat for harvest mice has been shown to be beneficial to many other

species, including other small mammals and priority farmland bird species. These

include the barn owl using rough grassland for hunting and other birds using wild bird

mixes such as the tree sparrow. The harvest mouse is also a good measure of

connectivity within the landscape, especially where it relies on arable field margins

and rough grassland. For these reasons practical habitat management for harvest mice,

as outlined in the factsheets, is a good starting point for conservation of many other

farmland species.

Project limitations and variables

As with all ecological studies there are limitations and variables that ideally if the

study was repeated would be taken into account.

o Nest searching was carried out during the months of October through until

April which can affect results as nests have often fallen from habitats such as

reedbeds during winter storms but can persist in dry grass for over a year.

Therefore wetland habitats should be visited in autumn.

o Weather conditions such as ice and snow can make nest searching very

difficult and unproductive. Flooding and storms can destroy nests in any

habitat making results hard to interpret. This is difficult to overcome in any

study as weather is unpredictable.

o The pellet sample size was often too small to be effective in finding harvest

mice, in many cases under ten pellets were collected when ideally 40 would be

the sample size.

o Some parts of Suffolk had more barn owl monitors collecting owl pellets than

others, a good spread of sites should be ensured.

o Some barn owls were not monitored or in some cases no pellets were collected

or they were not passed onto the project.

o Most barn owl pellets are regurgitated at daytime roosts which can be in a

different place than the nest site and sometimes hard to find.

o Barn owls catch different numbers of harvest mice during the year. Less are

typically taken in the summer as the vegetation is denser and hard for the barn

owl to hunt in – unfortunately this is when most of the pellets were collected

for this study. Ideally pellets would be collected in autumn as harvest mice are

preyed upon in higher numbers then after crops have been cut and numbers are

at their highest after the breeding season.

o A method for distinguishing field vole and harvest mouse ground nests should

be found so as not to exclude valid nest results.



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Abbey, G. 1909. The Balance Of Nature And Modern Conditions of Cultivation.

George Routledge & Sons, Limited

Bence, S.L., Stander, K., Griffiths, M. 2003. Habitat characteristics of harvest mouse

nests on arable farmland. Agriculture, Ecosystems and Environment. Vol.99, 179-186

Battersby, J. (Ed) & Tracking Mammals Partnership. 2005. UK Mammals: Species

Status and Population Trends. First Report by the Tracking Mammals Partnership.

JNCC/Tracking Mammals Partnership, Peterborough.

Buckley, J. & Goldsmith, J.G. 1975. The prey of the Barn owl (Tyto alba alba) in east

Norfolk. Mammal Review. Vol.5, No.1, 13-16

Glue, D.E. 1970. Avian predator pellet analysis and the mammalogist. Mammal

Review. Vol.1, No.3, 53-62

Glue, D.E. 1975. Harvest mice as Barn owl prey in the British Isles. Mammal

Review. Vol.5, No.1, 9-12

Haberl, W. & Krystufek, B. 2003. Spatial distribution and population density of the

harvest mouse Micromys minutus in a habitat mosaic at Lake Neusiedl, Austria.

Mammalia. Vol.67, Issue 3, 355-366

Harris, S. 1979. History, distribution, status and habitat requirements of the Harvest

mouse in Britain. Mammal Review, Vol.9, No. 4, 159-171

Harris, S. 1979. Secret life of the Harvest Mouse. Hamlyn Publishing Group Ltd

Ishiwaks, R., Kinoshita, Y., Satou, H., Kakihara, H., Masuda, Y. 2010. Overwintering

in nests on the ground in the harvest mouse. Landscape Ecology Engineering. Vol.6,

335-342

Kuroe, M., Yamaguchi, N., Kadoya, T., Miyashita, T. 2011. Matrix heterogeneity

affects population size of the harvest mice: Bayesian estimation of matrix resistance

and model validation. Oikos. Vol. 120, 271-279

Love, R.A., Webbon, C., Glue, D.E., Harris, S. 2000. Changes in the food of British

Barn Owls (Tyto alba) between 1974 and 1997. Mammal Review. Vol.30, No.2, 107-

129

Moore, N.P., Askew, N., Bishop, J.D. 2003. Small mammals in new farm woodlands.

Mammal Review, Vol.33. No.1, 101-104

Naunton, C.R. 1979. The Harvest Mouse in Suffolk in 1978. Suffolk Natural History:

The transactions of the Suffolk Naturalists‟ Society. Vol.18, 86-87



Report to PTES.

Perrow, M.R. & Jordan, M.J.R. 1992. The Influence of Agricultural Land Use upon

Populations of Harvest Mouse. Report to TERF, Hoescht UK.

Perrow, M.R. & Jowitt, A.J.D. 1993. Desperately seeking water shrew and harvest

mouse in broadland. Suffolk Natural History: The transactions of the Suffolk

Naturalists‟ Society. Vol.29, 6-11

Perrow, M.R. & Jowitt, A.J.D. 1995. What future for the harvest mouse? British

Wildlife. Vol.6, 356-365

Perrow, M.R. & Jowitt, A.J.D. 2003. Wetlands as an important habitat for small

mammals. British Wildlife. Vol.14, 171-179

Riorden, P, Lloyd, A & Macdonald, D. 2007. The status of the harvest mouse in a

lowland arable landscape. Report by WildCRU, Oxford University

Rowe, F.P. 1958. Some observations on harvest mice from corn ricks of a Hampshire

Farm. Proceedings of the Zoological Society of London, Vol.131, 320-323

Rowe, F.P. & Taylor, E.J. 1964. The numbers of harvest mice in corn ricks.

Proceedings of the Zoological Society of London, Vol.142, 181-185

Southwick, C. 1956. The abundance and distribution of harvest mice in corn ricks

near Oxford. Proceedings of the Zoological Society of London. Vol.126, Issue 3, 449-

452

Trout, R.C. 1978. A review of studies on populations of wild harvest mice. Mammal

Review. Vol.8, No.4, 143-158

Trout, R.C. 1978. A review of studies on captive Harvest mice (Micromys minutus

(Pallas)). Mammal review. Vol.8, No.4, 159-175

White, G. 1767. The Natural History of Selborne. Penguin Books

Yalden, D.W. 2003. The Analysis of Owl Pellets, 3rd

edition. The Mammal Society



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Other Project Outcomes

Volunteers: As part of the project volunteers were trained to analyse barn owl pellets.

Many of these volunteers were new to the Trust and volunteered for the first time

during the course of the project. Five pellet analysis training days were held, with a

total of 72 current barn owl monitors and 52 new volunteers trained. Three new

volunteers took part in longer term volunteering with the project doing data entry and

working on map info. One volunteer also spent time doing nest searches and came out

on field visits.

Engaging children: In partnership with Suffolk Wildlife Trusts Education Team,

activities for children included the following:

Owl pellet analysis at the Suffolk Show – May 2009

Owl pellet analysis at education centres using project resources and training for

staff and volunteers – ongoing

Owl pellet analysis with Framlingham Badgers (St John Ambulance junior group)

– November 2009

Article written for Wildlife Watch national magazine plus an RSWT video on the

project – Winter 2009/10

Owl pellet analysis at two school events supported by the project – Spring 2010

Owl pellet analysis at Schools Farms Fair – April 2011

Courses for the public: Two courses for adults ran during the project. The first was

held as part of SWTs Wildlearning Programme in September 2009 the second was a

PTES course held in October 2010.

Contact with landowners and site visits: In total 95 visits were carried out to a variety

of sites across Suffolk. Most were to landowners who had already been involved with

the Suffolk Community Barn Owl Project. At the time of the visit all landowners were

sent a harvest mouse factsheet, a newsletter, a copy of the analysed pellet sheet and a

letter to thank them for their time. When the project was completed all were sent the

new general and farmland management options factsheets plus a final newsletter

containing a summary of the project.

Newsletters & Factsheets: Four newsletters were produced during the projects

lifetime and distributed to pellet analysis volunteers, owl box monitors and

landowners. A new updated general factsheet and a farmland management option

factsheet were produced for future use by SWT (Copies of newsletters and factsheets

are included with the report).

Publicity: Written articles in Suffolk Wildlife Trust Magazine, East Anglian Daily

Times Newspaper, The Times Newspaper, BBC Wildlife Magazine, Country Living

Magazine, Wildlife Watch Magazine. Radio interviews BBC Radio Four Farming

Today and BBC Radio Suffolk.



Report to PTES.

Full data sets for figures 15-18:

Number of nests at all sites related to connectivity and site habitat type Connectivity

Score column

1- arable 2- arable

with grass

3-

arable

with

river

valley

4- lowland

wetland:

grazing

marsh,

fenland &

estuary

Average

number of

nests

1 – very well

connected

8/2

(total no. nests/ no. sites)

4 - average no. nests

22/2

11

42/9

4.6

66/13

5.1

(138/26)

5.3

2 – some

connectivity

16/7

2.3

50/17

2.9

23/11

2.1

0 (89/35)

2.5

3 – very poorly

connected

19/5

3.8

9/10

0.9

1/1

1

0 (29/16)

1.8

Average number

of nests

(51/14)

3.6

(81/29)

2.8

(66/21)

3.1

(66/13)

5.1

Presence/absence of nests at all sites related to connectivity and site habitat type Connectivity

Score column

1- arable 2- arable

with grass

3-

arable

with

river

valley

4- lowland

wetland:

grazing

marsh,

fenland &

estuary

Percentage

of total sites

with nests

present

1 – very well

connected

2/2

(No. of sites where nest

present/total no. sites)

2/2 9/9 13/13

100%

2 – some

connectivity

6/7 15/17 10/11 0

88%

3 – very poorly

connected

2/5 4/10 1/1 0

44%

Percentage of total

sites with nests

present

71%

72%

95%

100%

Acknowledgements Thanks goes to the Peoples Trust for Endangered Species and the Chadacre trust who

funded the project. Simone Bullion for advice on all aspects of the project. John

Dobson and Richard Woolnough for information on the harvest mouse in Essex and

Bedfordshire. Celia Miller for statistical help and creation of figures. Jan Cawston for

the many hours of expertise verifying owl pellet results. Also to the many landowners

who allowed access onto their land and volunteers who helped in many ways with the

project.

Where images are not credited they are taken by Martha Meek or Simone Bullion

suffolk’s harvest mice in focus - suffolkwildlifetrust.org · the overall aim of this project is...

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