In 1979, the annual Midwinter Bald Eagle Survey (MWBES) was initiated by the National Wildlife Federation to monitor the status of Bald Eagle wintering populations in the contiguous United States by estimating national and regional count trends, overall and by age class. The MWBES takes place during the first two weeks of January each year. In 2007, the U.S. Army Corps of Engineers (USACE) partnered with the U.S. Geological Survey (USGS) to assume the national coordination, administration, and management of the annual MWBES, including long-term database management, data analysis, reporting and publication thru January 2021. Many states still continue to participate and count both Bald and Golden Eagles along standard survey routes, with thousands of conservation agency personnel and volunteer “citizen scientists” contributing time and resources towards this national conservation effort.

The MWBES represents a unique source of long-term, baseline data on a species recently delisted by the U.S. Fish and Wildlife Service. Unlike nesting surveys, it provides information on both breeding and non-breeding segments of the population at a potentially limiting time of year. Key to success of management efforts supported by the MWBES has been the timely public availability of annual count data and periodic trend analyses. In accordance with the USGS and USACE partnering agreement for the MWBES (2007), a number of tasks were resourced including the most recent 30-yr (1986-2015) trend analysis completed in 2019. Eakle et al. (2015) reported 25-yr MWBES count trends from 1986-2010, while Eakle et al. (2013) reported Golden Eagle records collected during MWBES counts from 1980-2010. Boise State University statisticians ran hierarchical mixed models to estimate count trends with the 1986-2015 dataset, which will inform management recommendations for wintering Bald Eagles at USACE Civil Works projects in an O&M status (Eakle et al. In Prep).