MASSACHUSETTS 



Seabirds 



As in northern New England, both great black-backed and herring gull 

 populations expanded yery rapidly from the 1940's through the 1960's (Kadlec 

 and Drury 1968a, Drury 1973) (Table 29). Recently, there appears to have been 

 a reduction from population levels found in the 1965 to 1972 period for her- 

 ring gulls but not for black-backs. Local population shifts also are occurring. 

 Some Boston Harbor colonies are decreasing while others are increasing (J. 

 Hatch unpubl. notes). Although the large Muskeget Island population has de- 

 clined, the Coatue, Nantucket and Monomoy colonies have expanded considerably. 

 Causes of these population shifts require investigation. 



Laughing gull numbers expanded rapidly on Muskeget Island from the early 

 1900's to a peak of 20,000 pairs in 1940 (Nisbet 1971a, b, Wetherbee et al. 

 1972). Since then, the colony moved to Monomoy Island and numbers dwindled 

 until 1972 when only 135 pairs remained (I. Nisbet pers. comm.). In 1977, 

 they had increased to 200 pairs, providing some optimism for the future of 

 this species in the State. In Massachusetts, they nest near terns in upland 

 vegetation rather than in salt marsh (Spartina ) as they do in New Jersey 

 (Burger 1977) and furtfier south. 



Arctic terns, at the southern limit of their nesting range, have declined 

 by nearly 50% since 1972 (Nisbet 1973, 1976b). Major declines were found at 

 Plymouth Beach, Nomans Land Island, and Tern Island during the 1970's with 

 only modest increases at Nauset Beach and along the north shore (Nisbet 1973 

 pers. comm.). This species usually nest with common and roseate terns. 



Common tern populations also decreased by about 40% between 1972 and 1977 

 (Nisbet 1973 pers. comm.). Major shifts have occurred in colony location dur- 

 ing the 1970's. Dramatic reductions have occurred in the past 6 or 7 years at 

 the formerly large colonies at Nomans Land, Ram Island, Grays Beach, Plymouth 

 Beach, Monomoy and Snake Island. Increases have been found at Bird Island and 

 New Island, Nauset, but these increases have not compensated for the reduc- 

 tions at the major colonies. 



Roseate tern populations have decreased by about 70% over the past 25 

 years (Nisbet 1973 pers. comm.). Major declines have occurred at six of the 

 seven colonies. The two large colonies at Grays Beach and Nomans Land have 

 nearly vanished. More than 95% of the breeding population is concentrated at 

 only two colonies. This species is faring badly in New York as well and war- 

 rants consideration for "threatened" or even "endangered" status. 



Least terns are faring better than any of the other terns in the State 

 (Nisbet 1973 pers. comm., Blodget 1978). Thorough censusing in 1977 revealed 

 a population at least equal to the "peaks" of about 1,500 pairs during the 

 late 1940's (Nisbet 1973). Because of its asynchronous nesting pattern, small 

 colony size, and tendency to shift colony sites, the least tern is probably 

 underestimated in most censuses. Its population stability (or even increase) 

 in recent years is particularly surprising considering the degree of distur- 

 bance along the beaches by vehicles and other types of human recreation 

 (Blodget 1978). 



59 



