| Zusammenfassung: | 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 $3,426-\text{km}^{2}$ 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 canopy 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.
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