LEAD IN HAWKS, FALCONS AND OWLS DOWNSTREAM FROM A MINING SITE ON THE COEUR-DALENE RIVER, IDAHO

Mining and smelting at Kellogg-Smelterville, Idaho, resulted in high c oncentrations of lead in Coeur d'Alene (CDA) River sediments and the f loodplain downstream, where American Kestrels (Falco sparverius), Nort hern Harriers (Circus cyaneus), Red-tailed Hawks (Buteo jamaicensis), Great Homed Owls (Bubo virginianus), and Western Screech-owls (Otus ke nnicotti) nested. Nestling American Kestrals contained significantly h igher (P = 0.0012) blood lead concentrations along the CDA River (0.24 mug/g, wet wt) than the nearby reference area (0.087 mug/g). A 35% in hibition of blood delta-aminolevulinic acid dehydratase (ALAD) in nest ling Northern Harriers (P = 0.0001), 55% in nestling American Kestrels (P = 0.0001) and 81% in adult American Kestrels (P = 0.0004) provided additional evidence of lead exposure in the CDA River population. In nestling American Kestrels and Northern Harriers, ALAD activity was ne gatively correlated with lead in blood. An earlier report on Ospreys ( Pandion haliaetus) showed slightly less inhibition of ALAD than in Ame rican Kestrels, but no significant reduction in hemoglobin or hematocr it and no negative influence on production rates. The adult and nestli ng American Kestrels along the CDA River contained about twice as much blood lead as Ospreys during the same years (adult 0.46 vs. 0.20 mug/ g, and nestling 0.24 vs. 0.09 mug/g), but adults showed a 7.5% reducti on in hemoglobin (P = 0.0356) and nestlings an 8.2% reduction in hemog lobin (P = 0.0353) and a 5.8% reduction in hematocrit (P = 0.0482). We did not observe raptor deaths related to lead, and although the produ ction rate for American Kestrels was slightly lower along the CDA Rive r, we found no significant negative relation between productivity and lead. Limited data on the other raptors provide evidence of exposure t o lead along the CDA River. Several traits of raptors apparently reduc e their potential for accumulating critical levels of lead which is pr imarily stored in bones of prey species.