The kestrel (Falco tinnunculus) was once the UK's most familiar bird of prey, a ubiquitous sight hovering over motorway verges and farmland. Population declines of over 36% since the 1970s have placed it on the Amber List of Birds of Conservation Concern, reflecting a significant deterioration in fortunes linked primarily to the collapse of small mammal prey populations.
Ecology & Hunting
Kestrels are specialist hunters of small mammals (primarily field voles) detected from hovering flight using acute visual and UV detection of vole scent trail markings. They also take large invertebrates, earthworms, and small birds. The characteristic hovering flight — facing into wind with tail fanned and head still — is an adaptation for precise prey location before a stoop. In Britain, kestrels breed in tree holes, ledges on cliffs and buildings, and old crow nests from April to July.
Causes of Decline
Prey decline: Reduced field vole populations due to loss of rough grassland habitat is the primary driver. Agricultural improvement (ploughing rough grassland, increased grazing intensity) reduces vole habitat.
Loss of nesting sites: Modernisation of buildings, removal of old trees, and changes to farm infrastructure reduce nest site availability
Second-generation rodenticides: Anticoagulant rodenticide poisoning causes direct mortality and sublethal effects; detected in significant proportions of kestrels submitted for post-mortem examination
Conservation Actions
Rough grassland creation and management: tussocky permanent grassland with adequate vole prey is the most important habitat requirement
Nest box provision: kestrel nest boxes are effective and readily accepted; standard design is a wooden box 30cm x 30cm x 60cm with a 10-12cm entrance hole, sited 3-6m high on a pole, tree, or building
Reducing rodenticide exposure: using second-generation anticoagulant rodenticides only as a last resort; ensuring bait stations are sited to reduce non-target access
Agri-environment scheme options: field margins, beetle banks, and rough grassland creation benefit both kestrels and their prey