CASE STUDY: THE BALD EAGLE 



Introduction 



Bald eagles ( Haliaeetus leucocephalus ) have been treasured as our national 

 symbol in the United States since 1782. In the ecological community they have 

 an additional value as high level consumers and indicators of environmental 

 quality. A recent decline in their populations and the designation of eagles 

 as an endangered species resulted in widespread concern for their status. 

 Bald eagles nesting in Maine represent more than 90% of the known eagle 

 population breeding in the northeastern United States. Maine's eagles, 

 especially those inhabiting the characterization area, are more closely allied 

 to those of the Canadian Maritime provinces. Eagles breeding in coastal Maine 

 and Nova Scotia are the major remaining segments of a previously larger, 

 continuous maritime eagle population. 



Bald eagles inhabit the characterization area throughout the year. The Maine 

 coast supports more than 75% of the State's resident breeding and wintering 

 eagle populations and is used by spring and fall migrants. Coastal Maine 

 offers food chains capable of supporting eagles throughout the year, 

 relatively isolated sites for nesting habitat, and ice-free waters that 

 enhance eagle winter residence. 



Status 



Taxonomy . The American Ornithologists' Union (1957) recognizes two 

 subspecies of bald eagles. Breeding eagles and most wintering eagles in Maine 

 belong to the northern race (H. 1. alaskansus Townsend) . Southern bald eagles 

 (H. 1_. leucocephalus Linnaeus) are irregular visitors to the State. Palmer 

 (1949) cited a confirmed occurrence of the southern race in coastal Maine in 

 1890. These divisions are now considered arbitrary but have influenced 

 recognition of bald eagles as an endangered species. 



Historical distribution and abundance . No early appraisals of bald eagle 

 distribution or abundance in Maine are available. References to eagles appear 

 in the notes of James Rosier (1605), Captain John Smith (1614), and John 

 Josselyn (1672; in Palmer 1949) during explorations of coastal Maine. The 

 Abenaki Indians' word for eagle was "Sowangan" . The name "Swan Island" in 

 coastal Maine (region 2 and 5) is an adaptation of this word and implies 

 eagles were present, not swans, as commonly assumed (Palmer 1949). Names such 

 as Eagle Island, Eagle Hill (regions 1, 4, and 5), Eagle Bluff (region 4), 

 Eagle Lake, and Eagle Point (region 5), reinforce the historical importance of 

 the eagle. 



Previous population estimates imply eagle abundance in Maine has been 

 relatively low since the turn of the century. Knight (1908) suggested that 

 the breeding population did not exceed 100 pairs at the close of the 19th 

 century. Palmer (1949) considered 60 breeding pairs to be a liberal estimate 

 in the late 1940s. Historical breeding sites in the characterization area 

 documented prior to the initiation of State nesting surveys in 1962, are 

 summarized in table 16-10. 



16-33 



10-80 



