BALD EAGLE HOME RANGE COMPARISON

by


Christopher A. Schelb
Department of Biology
Lake Superior State University
Sault Ste. Marie, MI 49783


Abstract

A study to compare home range size and other habitat related oharacteristics of breeding Bald Eagle
(Haliaectus lecocephalus) was conducted within 2 general areas of the Lower Peninsula of Michigan.
The two locations consisted of a northern area comprised ofthe Manistee River having 2 nest sites
and the Au Sable River having 2 breeding areas, and the Saginaw Bay and River containing 4
breeding areas. The study was conducted during 1990 for the northern area and in 1996 for the
Saginaw Bay and River area. Adult Bald Eagles were captured and equipped with either a backpack
or tail-mounted transmitter prior to the breeding season. Locations of eagles were determined using
a hand-held Telonics receiver and an omni antenna to determine home range size during the breeding
season. Vegetative land cover types were determined and quantified within home ranges, as was the
maximum distance traveled from the nest. A general trend was observed in the home range size
which was greater in the north than in the Saginaw area. Statistical analyses were conducted using
either the Kruskal-Wallis test (Chi-Square Approximation), Mann-Whitney U test (t-test
approximation), paired t-test, or correlation. Correlation was done on the percent land cover type
versus home range size and the maximum distance verse home range size. The percentage of water
within a home range explained 46 percent of the variabilitv of a home range size among the 8
breeding areas (R-squared value=0.46). The maximum distance from the nest explained 38 percent
oœthe variability of a home range size among the 8 breeding areas (R-squared value=O.35), but was
not felt to be as good a determinant of home range size. A paired t-test was conducted for land cover
type comparison among the two areas which found no significant differences. Further refinement 0œ
home range differences could be achieved by comparing prey species density and prey vulnerability
among the 8 breeding areas.

Selected Literature

Stalmaster, M.V. 1987. The bald eagle. Universe Books, New York, N.Y.

Watson, J.W., M.G. Garret, and R.G.Anthony. 1991. Foraging ecology of bald eagles in the
	columbia river estuary. Journal of Wildlife Management. 55(3)492-499