Migratory Bird Program
Conserving the Nature of America

Bald Eagle Post-Delisting Survey Results

Bald Eagle

U.S. Fish and Wildlife Service 2009 (baseline) Bald Eagle Post-Delisting SurveyBackground:

The Final Post-delisting Monitoring Plan (Plan) details how the Service will monitor the status of the Bald Eagle through a series of surveys. The surveys involve collecting data on occupied nests and combine information from nest check monitoring activities conducted by the States and information from aerial surveys where sample plots are searched for nests. The set of known occupied nests will be statistically combined with the numbers of newly identified occupied nests to estimate the total number of nesting pairs in the contiguous 48 States. As identified in the Plan, the surveys will take place every five years over a 20-year period, with the initial (baseline) survey in 2009.

The surveys are designed to balance recovery monitoring with cost-effectiveness by setting the goal of the surveys as having an 80 percent chance of detecting a 25 percent or greater change in occupied Bald Eagle nests over any of the five-year intervals. Were this degree of decline to occur, even with no further increase in Bald Eagle numbers, the population would still be at a level recognized as recovered (in 2000, when the initial proposal to delist was published there was a population estimate of 6,471 Bald Eagles). If declines are detected, the Service will determine if Bald Eagles warrant expanded monitoring, additional research, or resumption of Federal protection under the Endangered Species Act (ESA).

Pilot Studies:
The Service collaborated with several States, representing a variety of geographic areas and a range of comprehensiveness of nest lists, to test the effectiveness of the survey design we now use for the post-delisting surveys. These pilot studies were conducted in Maine, Florida, Minnesota, Washington, and Missouri between 2004 and 2006 and were collaborations among USGS, Service, and State biologists experienced in Bald Eagle surveys (see Appendix 1 in the Plan for details).

The 2009 Baseline Survey:

The Service completed the 2009 Bald Eagle post-delisting survey in May of 2009 (See Appendix 2 in the Plan for a complete description of survey protocols). Table 1 (below) summarizes the States where aerial surveys were flown to sample area-search plots for eagle nests. Following the aerial survey effort, we continued to work with our partners to share nest list data with particular focus on representation of the States with lower known eagle nest densities.
We received nest list data from 30 of the 48 lower States and 10 of the 12 States originally identified as having the highest densities of known Bald Eagle nests. Having worked through some of the communication and logistical challenges, we anticipate a higher response rate for future surveys.

Survey Analysis and Results:
The Service has been continuing to work on the analysis of the data from the 2009 baseline survey as time allows. Recent prioritization of eagle-wind issues, and specifically the evaluation of site-specific risk of eagle take at proposed wind facilities, has delayed the post-delisting survey report. The Service will continue to work with State, Tribal, and other partners as we work toward completing the analysis and evaluate the results.

Table 1. Summary of the States surveyed, general survey timing, and observers/pilots involved in the 2009 Bald Eagle post-delisting survey.

Regions/States Surveyed

Survey Timing




State plane and observers



FWS plane, State observers



FWS and State planes, State observers

(DC, MD, VA, DE)


FWS planes, FWS and State observers



FWS plane, State observers

(IA, IL, MN, WI, MI)


FWS and State planes; FWS, State, Tribal and volunteer observers



FWS plane and contract plane and helicopters, FWS and volunteer observers

Suvey PlaneIn memoriam
On January 17, 2010, David S. Pitkin and V. Ray Bentley were lost when their small plane crashed as they were returning from conducting a mid-winter count of migratory geese and ducks along the Oregon Coast. Both Ray and Dave participated in the 2009 Bald Eagle post-delisting survey; they were dedicated, passionate biologists and will continue to be greatly missed. See full tribute article: http://www.fws.gov/oregoncoast/In_Memory_of_Dave_Pitkin_and_Ray_Bentley.htm

For A PDF of the Post Survey Report

Last updated: October, 2012.


Last updated: October 19, 2012