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Abstract:
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In the lower 48 United States, most state wildlife agencies have not maintained lists of location and status of nests of Bald eagles (Haliaeetus leucocephalus) since the last 2009 survey. Historically, these lists were the primary source of information on bald eagle populations. Over the last nine years nests have been left or destroyed as pairs leave to make and use nests at other locations. Also, a growing population has made new nests every year. We predict the list coverage to drop by over a half. While the nests lists are not as statistically valuable as in 2009, the dual-frame design is still worth maintaining.
The both the list and area frames are based on a grid of 10 by 10 km2 plots. The survey is divided into 15 strata over 20 of the 48 states with high densities of nests. The design accounts for the deficiencies in list coverage, detection of nests, and nest status. To make better use of flight time, we add the list sample to the area sample, so all habitat is searched for new nests before checking list nests in each plot. We use a hierarchical Bayesian version of the Haines-Pollock dual-frame screening estimator with multiple observer detection on new nests.
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