Osprey Distribution, Abundance, and Status in Western North America: II. The Oregon Population

Abstract

The present study was designed to determine the distribution and abundance of nesting Ospreys (Pandion haliaetus) in Oregon, and to evaluate the status of the population. Ospreys are sensitive indicators of environmental pollution and have been previously studied in most parts of their breeding range for this purpose. Furthermore, populations at many locations have declined during the last several decades (see review, Henny [1977a]). The Osprey is perhaps one of the easiest birds of prey to, study on a regional basis because of its specific habitat requirements and conspicuous nests. Therefore, following completion of the surveys from New York to Georgia along the Atlantic Coast (Henny et al. 1974, Henny and Noltemeier 1975, Henny et al. 1977), a survey of nesting Osprey populations in western North America was initiated in northern California in 1975 (Henny et al. in press); the present study of the Oregon nesting population was conducted in 1976 and follows the same procedures as used in the earlier surveys. Information concerning the present distribution and abundance was collected for two reasons: (1) to locate concentrations and other sites that may be in immediate jeopardy from logging or other land management practices, and (2) *to obtain information for evaluating future changes in distribution and abundance. Recent productivity data and comparisons of historical numbers with present numbers at localized sites are also reviewed to evaluate the present status of the population. Early records of Osprey abundance in Oregon were few, and the species was only designated rare or common, with no attempt at enumeration (e.g., Woodcock 1902, Jewett and Gabrielson 1929). After reviewing the historical records, Gabrielson and Jewett (1940:199) reported the Osprey in Oregon as,