Code

CCBTR-12-05

Publication Date

2012

Abstract

Sustaining the duel military and environmental stewardship missions on Aberdeen Proving Ground (APG) has become increasingly challenging as the number of eagles using the installation has grown dramatically. Military testing and training activities conducted on APG are vital to national security. APG likely holds the greatest conservation value for bald eagles of any federal property along the Atlantic Coast. The property supports a complex mixture of eagles including a growing breeding population that is rapidly approaching saturation, a large population of non‐breeding residents, and migrant populations from the northeast and southeast. Major activity centers such as active nests, communal roosts and foraging areas are protected under the disturb and sheltering provision of the federal Bald and Golden Eagle Protection Act. The level of site‐specific information on eagles required to tightly integrate their needs into the space requirements of a diverse and dynamic military operation has not been available. The focus of this project has been to collect and provide eagle information that will enable the incorporation of effective environmental planning into the military mission. Between 2007 and 2009 satellite transmitters were deployed on a large (n = 65) cohort of eagles that represent the cross section of populations that use APG. Between 2007 and 2011 transmitters collected nearly 700,000 GPS locations from within every state and Canadian province along the Atlantic Coast confirming APG’s role as a hub of eagle activity within eastern North America. Locations (n > 320,000) within the upper Chesapeake Bay were used in spatial models to develop probability surfaces that identify high‐use activity centers by season within APG. Midnight locations (n > 10,300) were used in separate spatial models to delineate communal roosts. Results of this study provide site‐specific information designed to inform future management decisions. Maps reveal the locations of significant communal roosts, foraging areas, loafing areas and movement corridors used by eagles on APG. Levels of use are quantified by location to facilitate prioritization of sites for management consideration. Seasonal and time‐of‐day patterns are provided to inform the scheduling of activities. The intersection of activity centers with the electrical infrastructure is examined to identify locations with the highest mortality risk. Lines intersecting with high‐use activity centers have produced mortality rates that are 42 times higher than lines intersecting with low‐use areas. Site‐specific information is provided to allow for the phasing of hazard mitigation. This report concludes the largest investigation of space use by bald eagles ever conducted. The project has clarified several aspects of eagle ecology within the upper Chesapeake Bay and has moved the science of eagle management forward in a way that will inform management throughout the species range. The still ongoing tracking database holds a great deal of promise for new ecological discoveries and management solutions.

Topic

Habitat Quality/Use/Movement; Survival/Mortality; Wildlife and Society; Tracking (Satellite)

Species

Bald Eagle

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