Kestrels have declined by over 50% in the UK since the 1970s, driven by loss of rough grassland hunting habitat and reduction of vole and invertebrate prey from agricultural intensification.
Kestrels that fail to find adequate small mammal prey experience energy stress that manifests as reduced flight performance, lower breeding success, and increased mortality. Chicks in poor prey years receive insufficient food, developing slowly and fledging underweight. Adults that successfully fledge chicks but cannot sustain their own condition deteriorate rapidly. Pesticide exposure through voles feeding in treated fields causes secondary toxicity. Vehicle strikes cause traumatic injury — kestrels disturbed from road verge prey are struck by passing traffic when flying low.