Seasonal blood lead concentrations in marsh harriers Circus aeruginosus from Charente-Maritime, France: Relationship with the hunting season

Abstract

This paper reports on lead contamination in marsh harriers Circus aeruginosus throughout the year. Blood samples were taken from pulli, fledged (first year) birds and adults. The results show very low blood lead (PbB) concentrations in pulli (median 0·8 μg/dl PbB). A marked seasonal difference in the distribution of PbB concentrations in first year/adult birds was found. Significantly more birds had an elevated ( > 30 μg/dl or > 60 μg/dl) PbB concentrations within than outside the hunting season, reflecting different levels of exposure to lead shot during these periods. In addition, a high proportion of regurgitated marsh harrier pellets contained lead shot during the hunting season (autumn/winters 1994 and 1995—25% and 15·6%, respectively), whilst only 1·4% of pellets contained shot during spring 1994, after the hunting season. These results provide compelling evidence that spent lead shot carried in the carcasses of prey is the source of lead contamination in marsh harriers in Charente-Maritime.