16 YEARS OF LEAD-POISONING IN EAGLES, 1980-95 - AN EPIZOOTIOLOGIC VIEW

A 16-yr (1980-95) retrospective study was conducted to assess differen ces in the prevalence of lead poisoning in Bald (Haliaeetus leucocepha lus) and Golden (Aquila chrysaetos) Eagles admitted to The Raptor Cent er at the University of Minnesota. These years encompass the period be fore and after federal legislation was enacted restricting the use of lead shot for hunting waterfowl on federal lands (1991). Of 654 eagle admissions reviewed, 138 cases of lead-poisoned eagles were evaluated for the following: recovery location, blood lead concentration, month of admission, radiographic evidence of lead in the ventriculus and pri mary cause of admission. The prevalence of lead poisoning in eagles di d not change after 1991, but mean blood concentrations of lead in the same population decreased. These findings call into question current t heories regarding the sources of lead for eagles and the actual mechan isms by which eagles are poisoned. Lead poisoning is a continuing prob lem both regionally and internationally, and many variables related to this toxicity have yet to be conclusively defined.