Laughing gull . Maine 1s the northern breeding limit of laughing gulls 

 and the population has never been very large. In 1895 there was only one 

 colony, Western Egg Rock, containing seven pairs (Gross 1945). In 1900, 

 approximately four pairs of nesting birds and 50 nonbreeding associates 

 remained in Maine (Norton 1924). By 1920 this colony had increased to 

 several hundred birds. In 1937 about 300 pairs were found on two islands, 

 and in 1940 about 300 pairs nested in the only remaining colony on Little 

 Green Island. Encroachment by herring gulls and grazing of sheep on 

 certain islands resulted in poor nesting conditions. Palmer (1949) reported 

 that after 1944 this species did not nest in Maine. Laughing gulls returned 

 to breed in the early 1950's when sheep were removed from Little Green 

 Island, but the gulls left when sheep were reintroduced. 



In 1969 and 1970 there were only three colonies in Maine with approxi- 

 mately 100 breeding pairs (Nisbet 1971). In 1977 six active laughing gull 

 colonies were found with an estimated population of 231 pairs. 



Common and Arctic terns . Drury (1973) pointed out several problems 

 that are encountered when one attempts to synthesize historical population 

 data on terns. The foremost of which is that until recently censuses in Maine 

 did not distinguish species (i.e., common or Arctic terns). Also, terns often 

 shift nesting locations from year to year making it difficult to compare data 

 obtained in successive years. Lastly, few researchers have been able to 

 conduct total nest counts; instead, the total number of birds flying above a 

 nesting colony has been estimated (excluding those nonbreeding birds loafing 

 near the colony). 



Allen and Norton (unpublished) listed 67 Islands on which terns nested 

 in Maine in 1886. By 1890 that number declined to 32 and by 1900 to about 

 16. Since 1900 terns have nested on 80 different Islands in Maine but have 

 occupied no more than 30 in a given year (Drury 1973). 



The history of common terns in Maine since 1900 has been one of early 

 increase followed by three decades of decline (Figure 10). From the early 

 1900's until the 1940's common terns Increased. Norton (unpublished) esti- 

 mated the population in 1931 to be 3,650 pairs in 19 colonies. Several 

 sources indicate that in 1940 the population peaked with approximately 8,000 

 pairs nesting on 25 Islands. From this peak the population declined to about 

 2,600 pairs on 18 islands in 1972 (Drury 1973). In 1977, 24 common tern 

 colonies with a total estimated breeding population of 2,095 pairs were found. 

 Many of the colonies were small; less than 50 pairs. Harassment by gulls and 

 Norway rats ( Rattus norvegicus ), overgrazing of cover by sheep, and human 

 disturbance are believed to have contributed to the recent decline. However, 

 common and Arctic terns have "been subject to ceaseless series of cycles with 

 an alternating ebb and flow of their numbers and contraction and expansion 

 of their breeding range" (Norton 1924). 



Arctic terns are less abundant now on the Maine coast than they have 

 been at any time in the last 75 years. According to Drury (1973), 5,500 pairs 

 of Arctic terns nested in Maine (including Machias Seal Island) in 1902 and 

 1911. Allen and Norton (unpublished) censused four major Arctic tern colonies 

 in 1930 and listed 1,650 pairs, excluding Machias Seal Island. Palmer (1949) 



48 



