Managing vegetation for the conservation of the Common Kestrel Falco tinnunculus on farmland in England

Abstract

Agricultural intensification is a major threat to a range of biodiversity. Of particular concern at a Europe-wide level are population declines of farmland birds, an index of whose numbers are taken to be an indicator of the health of biodiversity as a whole. In this thesis, I explore how to aid the populations of a declining farmland raptor, the Common Kestrel Falco tinnunculus, via the potential management of habitat, and then I link this to Agri-environment Scheme (AES) options, which require continual adaptive management to maximise their benefits. AESs have been responsible for the creation of additional areas of grassland in the British countryside, which could be expected to be of benefit to the Kestrel; a grassland hunter. A study of foraging breeding Kestrels showed that they select habitats non-randomly with cut grass being selected over all other available habitats. I then explored the potential effects of vegetation management on Kestrels’ preferred prey, small mammals, in a manipulative field experiment. While most small mammals will leave an area of grassland after mowing, I show that a small number may remain as long as some form of cover – such as the cut grass – remains in situ. I investigated the temporal effects on farmland bird species of cutting grass both within whole fields and on field margins, There was a rapid drop-off in use of grass fields after cutting suggesting a rapid decline in available resources. Field margins that were cut in strips were favoured by some species, although others preferred to use the longer, control, vegetation.Overall I conclude that targeted cutting of small patches or strips throughout the year would create mosaics of different habitat and therefore be of benefit to a range of different declining farmland biodiversity, and could be a worthwhile addition to AES field margin prescriptions.