mid-1970's at 20,000 pairs (Mendall 1976). In 1977 eider nests were found on 

 240 islands, and the breeding population was approximately 22,390 pairs. 



Great black-backed gull . This large gull has expanded its nesting range 

 southward during this century. No great black-backed gulls nested in New 

 England during the closing decades of the 19th century. Allen and Norton 

 (unpublished) stated that no great black-backed gulls nested in Maine in 1883 

 or 1914. Norton (1907) reported that this gull was roosting in small numbers 

 on three islands in Maine. Since the mid-1920's breeding black-backs have 

 increased in number along the entire coast of Maine. 



Norton (unpublished) found 25-35 pairs nesting at eight different loca- 

 tions in 1931. Gross (1945) estimated that the nesting population in Maine 

 was at least 1,700 pairs on 98 islands in the 1940's. Many of the colonies 

 consisted of only 1 to 5 pairs, but Gross found that black-backs in some 

 areas were in colonies of up to 150 pairs. Drury (1973) estimated that in 

 1972 the Maine breeding population of great black-backed gulls was approxi- 

 mately 7,500 pairs. In 1977, 220 great black-backed gull colonies were found 

 with an estimated population of 9,847 pairs (Figure 9). Black-backs usually 

 nested in association with herring gulls. 



Herring gull . William Drury has had a special interest in the herring 

 gull population of the Northeast, including Maine, and has compiled population 

 estimates for different periods of time based on interpretations of data of 

 various researchers. Allen and Norton (unpublished) stated that an 

 extensive inspection of the coast carried out in the summer of 1903, located 

 only 14 herring gull colonies, numbering about 11,000 pairs. In 1931, Norton 

 (unpublished) conducted another extensive search for seabird colonies and 

 found approximately 26,000 pairs on 65 islands. Drury (1973) noted that 

 some of the estimates by Norton appeared to be exceedingly high for some 

 colonies in the 1920's. Norton (unpublished) suggested that the control of 

 herring gulls was essential for the survival of smaller, more vulnerable terns. 

 Gross (unpublished) managed a gull control program, under contract from the 

 U.S. Fish and Wildlife Service, for a large section of the Maine coast between 

 1944 and 1952. Drury used Gross's unpublished data on the number of gull 

 eggs per island to estimate the breeding population. The control program 

 appeared to have limited and even reversed the growth of the herring gull 

 population in Maine for a short time. The gull control program may also have 

 accelerated the shift of gulls from the coast of Maine southward to 

 Massachusetts and from outer islands on the coast to ones closer to the 

 mainland (Drury 1973). 



The Maine population of herring gulls began to stabilize about 1945 

 (Figure 9) while the gull population in Massachusetts increased rapidly. The 

 southward extension of the breeding range continued during the 1950's. The 

 shift from outer islands toward centers of human population has continued 

 during the last 20 years. Drury (1973) believed that the population in Maine 

 remained relatively constant for the last 20 years and estimated that 29,000 

 pairs of herring gulls nested in the coastal region between Portland and the 

 Canadian border in 1972. The 1976-1977 census found herring gulls nesting 

 in 222 colonies with an estimated population of 26,037 pairs. 



47 



