EAGLE BIOLOGY

Bart W. O’Gara
Research Biologist (retired)
US Fish and Wildlife Service
Montana Cooperative Wildlife Research Unit
The University of Montana
Missoula, Montana 59812

Additional Eagle Control Information

 Bald Eagle (Haliaeetus leucocephalus)

Fig. 1. Left, Bald eagle, Haliaeetus leucocephalus; right, golden eagle, Aquila chrysaetos

Eagle Populations

Research indicates that golden eagles are maintaining static populations in areas undisturbed by humans. The wintering population south of Canada is estimated at 63,000 birds. Aerial surveys conducted by the USFWS in 12 western states show average densities of about 10 golden eagles per 100 square miles (4/100 km2) in midwinter study areas. Golden eagles also winter in parts of Alaska, Canada, and Mexico; however, the number in this latter group would not likely exceed 10,000 birds.

Current population survey information indicates a sizable and healthy population of golden eagles in the western states. The current breeding population for 17 western states is estimated at 17,000 to 20,000 breeding pairs. Information indicates a slight decline in the western population as a whole, with drastic declines in some specific areas associated with increased human activity.

Bald eagles occur across the continent from northern Alaska to Newfoundland, and south to southern Florida and Baja California. They are found on Bering Island and the Aleutian Islands. Two subspecies are recognized: the southern bald eagle (H. l. leucocephalus) and the northern bald eagle (H. l. alascans). The primary difference in appearance is size, the northern race being larger and heavier. There is a gradual increase in size from south to north.

The northern bald eagle population in Alaska is estimated at 35,000 to 40,000. In 1989, the breeding population of bald eagles in the continental United States (excluding Alaska) was estimated to be about 2,673 pairs. This estimate included both races. The nationwide January eagle count sponsored by the National Audubon Society indicated about 3,700 birds each year from 1961 through 1966. The annual midwinter counts coordinated by the National Wildlife Federation since 1979 have ranged from about 9,000 birds to more than 13,000 in the contiguous 48 states. In 1989, 11,610 bald eagles were counted in key wintering areas. The 1989 count does not represent a comprehensive national count, so it is not directly comparable to earlier counts. These January counts indicated four areas of greatest abundance nationwide: the upper half of the Mississippi Valley, the Northwest (Washington, Oregon, Idaho, and Montana), Florida, and the Chesapeake Bay area.

Editors

Scott E. Hygnstrom; Robert M. Timm; Gary E. Larson

Prevention and Control of Wildlife Damage Logo 1994

PREVENTION AND CONTROL OF WILDLIFE DAMAGE — 1994

Cooperative Extension Division Institute of Agriculture and Natural Resources University of Nebraska -Lincoln

United States Department of Agriculture Animal and Plant Health Inspection Service Animal Damage Control

Great Plains Agricultural Council Wildlife Committee

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