Wintering eagles need secure hunting perches, predictable food sources, and sheltered roosting areas.
Eagles stand more than 3 feet tall and have a 6- to 7 1/2-foot wing span, requiring large trees for suitable perches. Trees with large, widely spaced branches provide the structure these large raptors can use. Large shoreline trees adjacent to open water provide perch sites from which eagles can scan the water for food, and to which they return with prey to eat. Stands of mature conifers, particularly white pine, sometimes mixed with large hardwoods, provide sheltered roosting areas where eagles spend the night and periods of inclement weather. These roosts are characterized by large-diameter white pines spaced far apart to allow easy access into the roost and provide sufficient overhead cover. Roost trees are often found on easterly facing, steeper slopes so the birds can roost out of the prevailing winds.
Winter roost sites are typically located near foraging areas (i.e., ducks, geese, fish, and roadkill), though they may be some distance from the shore. Roosts must provide protection from the wind and from extreme cold, as well as open access to perch sites. Winter is stressful because cold temperatures increase energy demands and food can be difficult to obtain. Eagles spend many winter hours perching quietly in protected locations.
Eagles vary in their tolerance of human activity, depending on the individual eagle, the particular roost or perch, and even the individual human involved. Human activity near roosts and perches can interfere with foraging and disturb eagles from protected perches, increasing energy demands and sometimes forcing eagles to perch in exposed locations.
Winter bald eagle counts in New Hampshire increased since 1982 from two to a record 67 in 2008. Wintering bald eagles occur in limited areas, usually near open water, though they sometimes roost up to half a mile from water in the Lakes Region, the Great Bay area, and along open stretches of the Androscoggin, Merrimack, and Connecticut rivers.
Manage for structural habitat features (i.e., tree-branching patterns and stand densities) of shoreline perch trees and night roost areas. Avoid human disturbance of these sites from December through March.
4.3 Forest Management in Riparian Areas; 6.10 Woodland Raptor Nest Sites.
N.H. Fish and Game. Bald Eagle Profiles. http://www.wildlife.state.nh.us/Wildlife/Wildlife_profiles/profile_bald_eagle.htm Accessed February 23, 2010.