Investigation into the use of field edges by small mammals on the Writtle College Estate
The data collected during this study suggests that the creation of uncultivated two-metre-wide
margins at field edges has no influence on the total numbers of small mammals present but increases
the species richness. However, the marked difference in the numbers of bank voles supported by
the uncultivated margins indicates that the creation of this habitat has benefited this species and. to
a lesser extent, the common shrew. Both of these species prefer dense groundcover (Burton 1986,
Corbet & Harris, 1991) which is provided by the rank grasses of the uncultivated margins. It
appears that the uncultivated margins are of limited benefit to wood mice as this species is not as
dependant on dense groundcover, preferring woodlands and hedgerows (Burton 1986, Corbet &
Harris 1991). The lack of a seasonal difference in habitat use generally reflects the preferred
habitat type. This was emphasised by the bank voles' marked preference for the uncultivated
margins in the spring which may have been due to the availability of food, protection from the
weather or predators, or a combination of all three.
The almost even distribution of wood mice and common shrews throughout the uncultivated margins
seems to indicate that these species foraged more extensively than the bank voles, which appeared
to avoid the location near the junction with the open field, particularly in the autumn. This may
have been to keep away from the more exposed locations that might offer less protection from
predators and might differ when there is a tall crop in the field. It may also have been that wood
mice and common shrews strayed to the edges of the field to find their insect prey whereas the bank
voles arc mainly herbivorous (Burton 1986, Corbet & Harris, 1991).
Conclusions
Although the numbers of small mammals utilising the field edges with uncultivated two-metre-wide
margins was not substantially different from the field edges without uncultivated margins, the species
difference suggested that the uncultivated margins were of more benefit to those species that preferred
a habitat with dense groundcover, in this case bank vole and common shrew. Benefits to small mammals
generally, together with greater species richness, might be influenced by the siting of the uncultivated
margins. Uncultivated margins along field edges that abut woodlands or established hedgerows may
not only increase the habitat available to bank voles and common shrews but also benefit wood mice.
Although the latter species prefers woodlands and hedgerows they do, to a lesser extent, inhabit the
grassy uncultivated strips. Conversely, bank voles and common shrews do venture from the grassy
strips and were captured along field edges without the uncultivated margins. Further research into the
benefits of the siting of the uncultivated margins is merited.
Acknowledgements
The authors would like to thank Susan Tippler who collected the first year's data used in this
work for her BSc (Hons) dissertation.
References
BURTON M. (1986) Guide to the mammals of Britain and Europe. London: Treasure Press.
CORBET, G. B. & HARRIS, S. (1991) Handbook of British mammals. Third Edition. Oxford:Blackwell
Scientific Publications.
GURNELL, J. & FLOWERDEW, J. R. (1994) Live trapping small mammals - a practical guide. London:
The Mammal Society.
MAFF (2001). The Countryside Stewardship Scheme - information and how to apply. Cambridge: MAFF.
SMITH, H., FEBER, R. E., JOHNSON, P. J., MCCALLAM, K., JENSEN, S. P., YOUNES, M. &
MACDONALD, D. W. (1993) The conservation management of arable field margins. Peterborough:
English Nature.
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Essex Naturalist (New Series) 21 (2004)