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Migration patterns and wintering localities of American ospreys

January 1, 1972

North American ospreys (Pandion haliaetus carolinensis), banded primarily in the Middle Atlantic States and in New England, apparently migrate to their winter grounds in the West Indies and South America on a broad front. Ospreys do not return to the United States as 1-year-olds, but an estimated 28 to 55 percent returrt to their natal vicinity (state where hatched or an adjacent state) as 2-year-olds. The 2-year-olds (presumably nonbreeders) are estimated to represent 5 to 10 percent of the population on the northern breeding grounds. Nest studies suggest that about 6 percent of the population on the breeding grounds consists of nonbreeders (presumably the 2-year-olds). These birds are associated with nests but do not lay eggs or exhibit brooding behavior. The point to be made to individuals conducting nest studies on ospreys is that nests should not be classified as active if eggs are not laid, even though a pair is present. If nests with no eggs are excluded from studies, we believe the observed recruitment rates can be validly compared with the recruitment standard (production rate required to maintain a stable population) of Henny and Wight (1969).

Publication Year 1972
Title Migration patterns and wintering localities of American ospreys
Authors C. J. Henny, W.T. Van Velzen
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Wildlife Management
Index ID 5220959
Record Source USGS Publications Warehouse
USGS Organization Patuxent Wildlife Research Center