Wintering Bald Eagles at Southwest Nebraska Reservoirs

Authors

David E. Busch, Water & Power Resources Services

Date of this Version

6-1981

Citation

Busch, "Wintering Bald Eagles at Southwest Nebraska Reservoirs," from Nebraska Bird Review (June 1981) 49(2).

Comments

Copyright 1981, Nebraska Ornithologists' Union. Used by permission.

Abstract

As a part of Water and Power Resources Service (formerly Bureau of Reclamation) compliance with endangered species mandates, a study of Bald Eagle use of Lower Missouri Region reservoirs was initiated during the winter of 1979. The author, headquartered in McCook, surveyed a number of reservoirs in Kansas and Nebraska, including Nebraska's four southwest reservoirs.

While wintering Bald Eagles on the Platte River, Harlan County Reservoir, and the Lewis and Clark Lake area have been the subjects of previous studies, the southwest reservoirs have received little such attention. Since wintering Eagle populations at these four reservoirs are relatively low, this was not unexpected. What was surprising to Nebraskans studying the Bald Eagle was the late winter-early spring concentration at Swanson Reservoir, discovered by this survey.

Data reported here were gathered on biweekly aerial surveys conducted over the winter of 1979-80_ Survey dates were modified somewhat due to poor weather or aircraft availability. Information from aerial surveys was supplemented by ground surveys through the Bald Eagle use period.

A general summary of Bald Eagle utilization of the four southwest reservoirs follows: Enders- sporadic, moderate use with greatest numbers of Bald Eagles reported in autumn and early winter, coincident with migratory peak of ducks using Enders waterfowl refuge; Medicine Creek (Harry Strunk L.)- consistent, low use with one to four Eagles seen virtually throughout the winter, but no peak numbers observed during the Bald Eagle use period; Red Willow (Hugh Butler L.)- sporadic, low use with no Eagles seen through most of the winter, but with a small spring build-up; Swanson- sporadic, high use with numbers moderate to low throughout winter, building to a high peak in late winter to early spring.

The following table lists complete results of the 1979-80 aerial survey. Survey results for 1978-79 weren't complete since aerial surveys weren't started until midwinter; however peak numbers at Swanson were equally impressive in the spring of 1979. Aerial survey data from 197879 as well as ground survey data from both survey years are similar and support the data presented here. Aerial surveys will continue through the winter of 1980-81.