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Each January, several hundred individuals count eagles along standard, non-overlapping survey routes as part of a nationwide Midwinter Bald Eagle survey. Nationwide counts of eagles were coordinated by the National Wildlife Federation from 1979 until 1992, when the Bureau of Land Management’s Raptor Research and Technical Assistance Center assumed responsibility for overseeing the count. Responsibility for count coordination shifted to the National Biological Survey (1993-1996) and later to the U.S. Geological Survey (USGS), Forest and Rangeland Ecosystem Science Center, Snake River Field Station.

Initial objectives of the survey were to establish an index to the total wintering Bald Eagle population in the lower 48 states, to determine eagle distribution during a standardized survey period, and to identify previously unrecognized areas of important winter habitat. Millsap (1986) reported results of the midwinter survey from 1979 through 1986. Beginning in 1984, National Wildlife Federation officials asked participants to count eagles along standard routes to provide data on count trends. Steenhof et al. (2002) published an analysis of count trends from 1986-2000. This report presents results of a follow-up evaluation of using data from 5 additional years. This 20-year analysis used the same methods used in the 15-year trend analysis (Steenhof et al. 2002).


This document was initially posted under partnership with the Northwest Alliance for Computational Science and Engineering, the United States Geological Survey, and the United States Army Corps of Engineers. A plain-text version of the 20-year analysis has been reproduced here for reference under agreement with Boise State University, to keep this information in public hands.