LEAD-POISONING IN WILD POPULATIONS OF MARSH HARRIERS CIRCUS-AERUGINOSUS IN THE CAMARGUE AND CHARENTE-MARITIME, FRANCE

Lead poisoning of waterfowl, through the ingestion of spent gunshot, h as been recognized as a mortality factor for over a century. However, in Europe relatively little attention has been paid to raptors that ma y ingest shot embedded in the flesh of prey. The present study examine s the incidence of lead poisoning in wild Marsh Harriers Circus aerugi nosus trapped at two sites in France, the Camargue and Charente-Mariti me. Eight captive Marsh Harriers (controls) had blood lead (PbB) conce ntrations of 5.3-10.8 mug per dl. Of 94 wild birds trapped during the winters of 1990/1991 and 1991/1992 either in baited clap traps or in m ist nets at night roosts, 29 (31%) had elevated (>30 mug/dl) PbB conce ntrations and 13 (14%) had concentrations indicative of clinical poiso ning (>60 mug/dl). Similar percentages of birds caught using the two t rapping methods had elevated (>30 mug/dl) PbB concentrations. However, clap netting appeared to select for more heavily contaminated birds a nd for juvenile birds, although the two are not necessarily correlated . In the Camargue, significantly more females than males trapped in cl ap nets had elevated PbB concentrations. The incidence of shot in regu rgitated Marsh Harrier pellets increased significantly between October and December, indicating increased exposure to lead as the hunting se ason progressed. There appeared to be a parallel increase in PbB conce ntrations throughout the hunting season, although this could not be cl early demonstrated as sex ratios were different during different sampl ing periods. Elevated PbB concentrations of harriers in the Camargue a re likely to result primarily from the ingestion of shot in the flesh of crippled or unretrieved waterfowl and in Charente-Maritime, from ea ting crippled or dead mammals. Other raptors at risk from lead poisoni ng and solutions to this problem are discussed.