USE OF SATELLITE TRANSMITTERS TO DELINEATE BALD EAGLE COMMUNAL ROOSTS WITHIN THE UPPER CHESAPEAKE BAY

Although Bald Eagle (Haliaeetus leucocephalus) roosts are protected under the federal Bald and Golden Eagle Protection Act, we have little systematic information on the distribution and abundance of roosts, and a policy framework that governs day-to-day management decisions has not been developed. We used satellite transmitters (n = 63) deployed OH Bald Eagles that represented a cross section of age classes and populations present within the study area. The units were programmed to record nocturnal roost locations (n = 10 321) to assess roosting behavior and to delineate the boundaries of communal roosts within the upper Chesapeake Bay. More than 27% (n = 2800) of roost locations were not associated with communal roosts and were assumed to reflect solitary roosting. The remaining 72% (n = 7475) of roost locations were clustered within 170 communal roosts that varied in area (0.04-20.13 ha), relative use (5-755 roost-nights), and number of transmittered birds present (2-35). The number of communal roosts within the study area has grown 10-fold over die past. 20 yr, presumably reflecting the growth of source populations and eagle use of the area.