Mortality of Sparrowhawks and Kestrels

B 1963 and 1979, the carcases of 341 Sparrowhawks Accipiter nisus and 616 Kestrels Falco tinnunculus were examined at Monks Wood Experimental Station, Cambridgeshire, to find the cause of death. The carcases were sent in by members of the public, in response to advertisements in national bird journals. All carcases were requested, irrespective of region and form of death. The main objective was to obtain tissues for analysis of pesticide residues, but, in addition, each carcase was autppsied, taking account of any notes from the sender on the circumstances of death. From most specimens, liver samples were analysed to determine the concentrations of DDE (from the insecticide DDT) , PCB (from industrial polychlorinated biphenyls), and H E O D (from the insecticides aldrin and dieldrin). This paper gives the results of the post-mortem examinations, but mentions the analytical results Only briefly, as these have been reviewed in detail by Cooke et al. (1981). During most of the period covered here, aldrin and dieldrin were used mainly against the wheat bulb-fly Dilia Coarctatd. For some purposes, we assumed that areas where this pest was a major problem (called 'wheat bulb-fly areas') had a heavier use of aldrin and dieldrin than elsewhere.