Heptachlor seed treatment contaminates hawks, owls, and eagles of Columbia Basin, Oregon
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Resource Abstract:
We evaluated organochlorine residues in 12 species of hawks. owls, and eagles from the Columbia Basin of Oregon between 1978
and 1981. Companion studies showed that heptachlor epoxide (HE) induced adult mortality and reduced productivity of the Canada
Goose (Branta canadensis) and American Kestrel (Falco sparverius).ln this study, brain tissue from raptors found dead and
sample eggs from 90 nests were analyzed for organochlorines. The primary concern was HE that entered raptor food chains through
the ingestion of heptachlor-treated seed by their prey. HE residues were detected in eggs from 9 of 10 species and ranged
as high as 4.75 ppm (wet wt), but no definite effects of HE on productivity were readily apparent from the limited series
of nests. However, the hazard of heptachlor seed treatments to birds of prey was demonstrated by the occurrence of lethal
residues of HE in brain tissue of 3 Golden Eagles (Aquila chrysaetos) and 1 Rough-legged Hawk (Buteo lagopus). Other organochlorine
pesticides were present in the eggs and significant relationships were found between DDE and eggshell thickness for the Swainson's
Hawk (Buteo swainsoni) and Western Screech-Owl (Otus kennicotti), although shell thinning (9.6% and 7.4%) was below the generally
accepted range where reproductive problems have been known to occur.
Citation
Title Heptachlor seed treatment contaminates hawks, owls, and eagles of Columbia Basin, Oregon