LE3 .A278 1982

1982

Smith, Peter

Acadia University

Master of Science

Masters

Biology

Biology

Bald eagles Haliaeetus leucocephalus alascanus Townsend were studied on the Shubenacadie River, Nova Scotia, from November to March, 1980-1981 and 1981-1982, to determine abundance and age structure, food resources and effects of tide and ice on fora.ging. Eagles arrived in November and left in March; peak numbers were 65 and X 4 7. Immatures increasingly outnumbered adults as winter progressed., Eagles concentrated in a 6 km stretch because of availability of tomcod Microgadus tomcod (Walbaum), pig carcasses at a farm, and suitable perches. Immatures were more numerous in this stretch than elsewhere. Tomcod spawn in the river in January, and are present before and after spawning. Eagles obtained fish under certain tide and ice conditions. Common mergansers Mergus merganser L. were also caught under specific tide and ice conditions. Most activity occurred in early morning and late afternoon, but foraging took place whenever conditions permitted. When the river was ice-free, eagles were most active at low tide; with ice, tide had little effect. Eagles utilized certain perches consistently, and many used a communal roost. Birds were trapped and marked from 1977 to 1982; some returned yearly, and some individuals were seen several times in a season. Eagles appeared elsewhere in Nova Scotia the same winter they were tagged.

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