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Title: High rates of nonbreeding adult bald eagles in southeastern Alaska

Present knowledge of bald eagle (Haliaeetus leucocephalus) demography is derived primarily from populations in environments that have been drastically altered by man. Most reproductive studies were done in the 1960's and 1970's when chemical toxins were inhibiting bald eagle productivity. Earlier, the removal of old-growth forests and decimation of anadromous fish runs by Euro-Americans may have greatly reduced bald eagle abundance from presettlement levels. Historical trends in this species are of interest because fundamental differences may exist between populations in pristine and man-altered environments. One difference may be breeding rate. Surpluses of nonbreeding adult bald eagles during the nesting season are rarely mentioned in the literature. Most surveys of reproductive success focus exclusively on eagles at nest sites, which assumes nearly all adults attempt to breed each year. The authors report that a majority of adults in the relatively pristine habitats of southeastern Alaska do not breed annually. This finding is important because if surpluses of non-breeding adults are a natural feature of the population, then hypotheses on density dependent population regulation and the evolution of delayed maturation are suggested. If, on the other hand, the abundance of nonbreeders is an artifact of recent environmental perturbations, serious population declines maymore » occur in southeastern Alaska.« less
Authors:
;
Publication Date:
OSTI Identifier:
5558371
DOE Contract Number:
AC05-84OR21400
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Wildl. Manage.; (United States); Journal Volume: 49:2
Research Org:
Fish and Wildlife Service, Juneau, AK
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; BIRDS; BIOLOGICAL ADAPTATION; REPRODUCTION; ALASKA; ANIMAL BREEDING; ENDANGERED SPECIES; ANIMALS; FEDERAL REGION X; NORTH AMERICA; USA; VERTEBRATES 560305* -- Chemicals Metabolism & Toxicology-- Vertebrates-- (-1987)