12-23 



for four of the five years occurred in Area 3; for the other year, 

 highest numbers occurred in Area 5. 



The distribution of birds within the harbor is related to the 

 availability of feeding and resting habitat. The greater scaup, a 

 diving duck, feeds by diving in water to depths of two to ten feet and 

 rarely ventures onto land. This species is dependent on animal food for 

 part of its diet and heavily utilizes animal material when inhabiting 

 salt water. Cronan and Halla (1968) examined the gizzards of 157 greater 

 scaup shot on or near the Rhode Island coast during the months of Nov- 

 ember, December and January, 1954-1957. Plant material occurred in 

 31.2% of the gizzards but accounted for only 1.2% of the total food 

 volume. In contrast to this, animal material occurred in 94.3% of the 

 gizzards and accounted for 98.8% of total food volume. The most impor- 

 tant animal foods were the soft-shelled clam {Mya arenaria) , eastern mud 

 snail {Ilyanassa obsoleta) and the dwarf surf clam {Mulinia lateralis) . 



The lesser scaup appears to consume more plant material than 

 the greater scaup (Kortright, 1942) . Birds collected throughout the 

 country revealed 78% of the fall diet and 67% of the winter diet to be 

 composed of plant life (Martin et al . , 1951); however, Rogers and 

 Korschgen (1966) believe that the lesser scaup feeds primarily on animal 

 material. Of 27 gizzards collected on the Rhode Island coast in winter, 

 animal material was found in 88.9% of all gizzards and totaled 85.1% by 

 volxmie; the dominant species found in these analyses included the 

 eastern mud snail, alternate bittium {Bittium alternatum) and the lunar 

 dove-shell {Mitrella lunata) (Cronan and Halla, 1968) . 



The third diving duck found in significant numbers in New 

 Haven Harbor is the common goldeneye {Bucephala clangula) . This species 

 is also heavily dependent on animal food with 77% of the fall and winter 

 diet being composed of animal material (Martin et al . , 1951). The Rhode 

 Island study by Cronan and Halla (1968) found animal material in 54.6% 

 of all gizzards; half the 82.4% volume of animals fed upon was unidenti- 

 fied decapods, primarily crabs. Stott and Olson (1973) concluded the 

 major animal component of the diets of common goldeneye found off the 



