Gulls of several species are the rpost abundant and conspicuous birds on New England 

 tidal flats. They feed on a wide variety of fish and invertebrates and scavange hurran 

 waste. (Photo by L.C. Goldman; courtesy U.S. Fish and Wildlife Service) 



birds from preferred areas by herring 

 gulls (Nisbet 1973), and also from winter 

 predation pressure by residents of the 

 Guianas on the northern coast of South 

 America (W.H. Drury; College of the 

 Atlantic; Bar Harbor, Maine; April 1981; 

 personal communication). 



Most gulls and terns are highly gre- 

 garious. They are colonial breeders and 

 often gather in large groups where food is 

 concentrated. It is impressive to witness 

 the accumulation of a group of feeding 

 gulls. Initially only one or two nay be 

 within sight, but within a few minutes 

 there may be one hundred or more. Group 

 feeding techniques in gulls have been 

 examined by Frings et al. (1955). They 

 found that food finding and the accumula- 

 tion of feeding groups resulted from the 

 combination of auditory and visual cues. 



There is a constant visual surveillance of 

 all parts of the coast by individuals or 

 small groups of birds. A bird that has 

 spotted food flies a characteristic figure 

 eight flight pattern in an attempt at prey 

 capture and emits a characteristic call. 

 Gulls within sight respond to the flight 

 pattern and those within earshot respond 

 to the call. Terns may also form feeding 

 groups via auditory and visual cues (Erwin 

 1977). 



Colonies may serve as information 

 centers and be an important aid in food 

 finding, particularly for species that 

 feed in groups on a patchy resource (Ward 

 and Zahavi 1973; Erwin 1978). Davis (1975) 

 found that the nests of gulls that consis- 

 tently fed together at fish docks were not 

 randomly dispersed in the breeding colo- 

 nies, but were clumped, suggesting that 



57 



