The effect of differences in the diversity, structure and management of organic and conventional farms in south-west Britain on small mammal populations

A 12 month MSc by research by Felicity Bates.

Supervised by Stephen Harris.

Handling a bank vole
© Mammal Research Unit
Bank vole.
Photo by Catherine Davey


Over the last 50 years, the intensification of British agriculture has led to a large reduction in the number of hedgerows, woodlands and other semi-natural habitats, and has been linked to a reduction in the biodiversity of agricultural areas.

In recent years there has been a shift away from the government providing funds that encourage intensive food production and towards schemes that promote biodiversity through hedgerow and woodland planting and restoration, and the conversion of arable land to temporary and permanent set-aside. One major scheme directed at the whole farm supports the conversion to organic agriculture. The consensus of research is that organic farming has a beneficial effect on biodiversity. Yet, despite the large amount of funding directed to agri-environment schemes and organic conversion, there as not been sufficient research into the effect of non-cropped habitat management on farmland biodiversity.

I will compare the diversity, structure and management of non-cropped habitats on organic and conventional farms, focussing on small mammals. Small mammals are of particular interest as they are important species in the agricultural food web and their numbers influence many species at different trophic levels including invertebrates, carnivorous mammals and birds of prey. They may also be useful indicators of the overall biodiversity of the farmland ecosystem, although research is still underway.

The species of small mammals most commonly found on British agricultural land are wood mice (Apodemus sylvaticus), common shrews (Sorex araneus), and bank voles (Clethrionomys glareolus). Other species that are present, but in smaller numbers, are pygmy shrews (Sorex minutus), field voles (Microtus agrestris), yellow-necked mice (Apodemus flavicollis) and harvest mice (Micromys minutus).

Project aims

  1. To compare the structure and diversity of the farmland landscape (including crop type, field margins and non-farmed habitat) through Phase 1 habitat surveys of 15 organic and 15 conventional farms.
  2. To compare the abundance and diversity of small mammals on conventional and organic farms in features that are most different between the two farm types (identified in aim 1).
  3. To determine which habitat variables correlate most strongly with small mammal numbers and diversity and, from this, make recommendations for the incorporation of management methods of benefit to small mammal populations.

Contact details

Felicity Bates
School of Biological Sciences
University of Bristol
Woodland Road
Bristol BS8 1UG, U.K.

Tel: 0117 9287593
Email: Felicity Bates