NONBREEDING BALD EAGLE COMMUNAL AND SOLITARY ROOSTING BEHAVIOR AND ROOST HABITAT ON THE NORTHERN CHESAPEAKE BAY

We studied roosting behavior and habitat use of nonbreeding bald eagles (Haliaeetus leucocephalus) on the northern Chesapeake Bay during 1986-89. In summer and winter, 11 and 13 communal roosts, respectively, and many solitary roosts were used simultaneously in the 3,426-km2 study area. Radio-tagged eagles roosted solitarily with differing frequency by season (60, 21, 39, and 44% of 81 eagle nights in summer, fall, winter, and spring, respectively) (P < 0.05). Roost trees, predominantly oaks (Quercus spp.) or yellow poplars (Liriodendron tulipifera), were larger in diameter and provided greater conopy cover than random trees (P < 0.05). Roost sites had snags present more often than did random sites (P < 0.01). Most roosts (86%) were in woodlots > 40 ha, and none were in human-developed habitat. In contrast, only 23% of random sites were in woodlots > 40 ha, and 9% were in developed areas. Roosts were farther from human development than were random sites (P < 0.05); 57% of the roosts were found on public lands, compared to only 20% of the random sites (P < 0.001). Winter roost sites were protected from prevailing northerly winds more often than were summer sites (P < 0.05). We prescribe a 1,360-m-wide shoreline management zone that extends 1,400 m inland to encompass roost sites and provide a buffer from human disturbance.