Habitat 



Characteristics of eagle habitat . Bald eagle habitat is closely 

 associated with bodies of water, which provide the preferred diet of fish. 

 Coastal marine and estuarine systems contain 82% of all the eagle breeding 

 sites known in the characterization area. Lacustrine and riverine habitats 

 support only 17% and 1%, respectively, of the breeding areas in coastal Maine. 

 Most nests are located on offshore islands and nearby headlands adjacent to 

 bays. The relative isolation of these sites offers ideal breeding habitat to 

 eagles . 



Bald eagles nest generally near large water bodies. The distance of 118 nest 

 sites in Maine from open water averages only 149 yards (135 m) . Eighty-one 

 percent are within 275 yards (250 m) . Mean distance from the shoreline varies 

 significantly in different habitats from 44 yards (40 m) on coastal islands to 

 253 yards (230 m) on nearby headlands. This contrast between adjacent areas 

 probably results from greater shoreline development and greater human activity 

 on the mainland. 



Nest locations near water provide both proximity to a food source and exposure 

 of the site. Exposure allows maximum visibility from the nest, a clear flight 

 path to and from the nest, and updrafts favorable for flight. The high 

 proportion (88%) of supercanopy and dominant nest trees used by eagles in 

 Maine also reflects exposure requirements. Seventy-three percent are old- 

 growth white pines, which normally offer superior height and whorls of strong 

 limbs to support nests. 



Eagle populations in coastal Maine are probably largest during winter. All 

 eagles observed in the characterization area during midwinter surveys were 

 found in marine and estuarine habitats. Inland lakes, ponds, and rivers are 

 used infrequently, since winter ice cover limits foraging opportunities. 

 Wintering eagles also favor undeveloped shoreline habitats although they 

 appear to be more tolerant of human activities than breeding eagles. Tall 

 white pines near open water are favored winter perches. They provide a wide 

 panorama, are accessible, and have stout horizontal branches for secure 

 perching. 



Food Habits 



Bald eagles are capable but often inefficient predators and generally adopt an 

 opportunistic strategy that includes scavenging carrion. They forage 

 primarily in areas of open water. Land-based feeding attempts also are 

 limited to open areas rather than forested habitats. 



The diet of Maine eagles varies considerably in different habitats. More than 

 90% of eagle food remains observed at nest sites during the breeding season in 

 freshwater habitats were fish, primarily bottom-dwelling species, such as 

 brown bullhead, chain pickerel, and white sucker. Fish represent only 35% of 

 the food debris in marine and estuarine systems. Bottom-dwelling species, 

 such as tomcod and sculpins, often are eaten but eagles also eat alewives, 

 blueback herring, and American eels. 



Maine eagles increasingly depend on birds as a food source during winter. 

 Avian remains constitute over 80% of eagle food debris in coastal Maine on a 



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