Post-delisting Monitoring Plan for the Bald Eagle - March 2009 Final
Below is the Summary of the Post-Delisting Monitoring Plan, click here to download a PDF file of the complete 76-page Plan.
The Post-delisting Monitoring Plan (Plan) will monitor the status of the bald eagle by collecting data on occupied nests over a 20-year period with sampling events held once every 5 years starting in early 2009. The Plan will continue the nest check monitoring activities conducted by the States over the past years and add census of area sample plots. The area sample plots will be selected from eagle habitat across the contiguous 48 States based on known nesting density. The set of known occupied nests (list frame) will be combined with the numbers of newly identified occupied nests from the area plot samples (area frame) to provide a dual frame estimate (Appendix 1). Statistically combining the results of these two data sets will provide a single estimate for the bald eagle population of the contiguous 48 States that more closely represents the actual nesting population of bald eagles than either the traditional nest check for occupancy or area plot sampling alone, based on our pilot studies in Maine, Minnesota, Florida, Washington and Missouri (Appendix 1). Reduction in future nest check monitoring (list frame) by the States will be compensated by sampling the list frame during the area plot surveys. In addition, dual observer sampling protocols are recommended to reduce bias (Appendix 2). Some States, particularly those with sparse numbers of nesting pairs, are currently collecting data in a highly accurate manner and may not need to employ the dual frame methodology. Data from these States will be included as a complete census.
The Plan recommends that the State agencies continue the occupied nest survey data collection and submission and assist with the area surveys while the U.S. Fish and Wildlife Service (Service) coordinates the area survey, manages the database, provides expertise including dual frame sampling design and data analysis, and initially funds the area sampling. This Plan is not intended to replace specific plans to manage eagles or monitor them in a different manner for specific management purposes.
The sample design is based on an 80 percent chance of detecting a 25 percent or greater change in occupied bald eagle nests over any period, measured at five-year intervals. We believe this is a goal that will both ensure recovery and be cost-effective. Were this degree of decline to occur with no further increase, the bald eagle population would still be at a level recognized as recovered (from 9,789 occupied nests when the bald eagle was delisted in 2007 to 7,342 occupied nests, a 25 percent reduction) based on a population estimate of 6,471 when the initial proposal to delist was published in 2000. If such declines are detected, the Service’s Bald Eagle Monitoring Team in conjunction with the States will investigate causes of these declines, including consideration of natural population cycles, weather, productivity, contaminants, other mortality factors, habitat changes or any other significant evidence. The result of the investigation will be to determine if the population of bald eagles in the contiguous 48 States warrants expanded monitoring, additional research, and/or resumption of Federal protection under the Endangered Species Act (ESA). At the end of the 20 year monitoring program, we will conduct a final review. It is the intention of the Service to work with all our partners toward maintaining continued species population expansion and management.