the lake-plateau region of interior Ungava preferred to nest by bog ponds and 

 other waters in open lichen-spruce woodland. 



Feeding Johnsgard (1975) noted that foraging Surf Scoters fed in shallow- 

 er waters than did White-winged Scoters and indicated that Surf Scoters forage 

 closer to coasts than do either of the other two scoters. 



Winter and Offshore Most of the wintering population is exclusively marine 

 but small numbers also winter on the Great Lakes (Palmer 1976b). Palmer (1976b) 

 indicated that non-breeding Surf Scoters are found more typically in the lit- 

 toral zone of the ocean than are the other two scoter species. Others are found 

 on adjoining coastal estuaries and bays. In the northeast, sandy substrates 

 that harbor molluscs important in the diet are favored. All three species of 

 scoters tend to congregate at the mouths of estuaries where food is more plenti- 

 ful (Stott and Olson 1974 in Bellrose 1976). 



FOOD AND FEEDING BEHAVIOR 



Surf Scoters dive for their food. They dive either with wings closed or 

 with half-spread wings, and they may or may not use their wings for propulsion 

 underwater. Diving birds may clear the surface before a dive and may dive 

 either straight down or at an angle (Palmer 1976b). 



Diving periods off the shores of the North Pacific ranged from 19 to 45 

 sec, with the lowest mean (20 sec, n = 9) recorded in the shallowest water and 

 the greatest mean (43.25 sec, n = 4) recorded in the deepest (Alford 1920). 

 Surf Scoters wintering near Vancouver, British Columbia, dove for 32.7 to 65.3 

 sec (mean = 51.9 + 2.29) in about 3.1 to 9.2 m (10.2 to 30.1 ft) of water (Dow 

 1964). 



The sequence of dives made by a Horned Grebe and a Surf Scoter near Comax, 

 Vancouver Island, British Columbia, and the behavior of the grebe suggested that 

 these two species were feeding commensally (Pearse 1950). The grebe dove short- 

 ly after the scoter did and apparently obtained food dislodged by the feeding 

 scoter. Paulson (1969) later reported similar observations of two Horned Grebes 

 and a Surf Scoter at Deception Pass, Whidbey Island, Washington. 



We know of no detailed information on the food habits of the Surf Scoter 

 in the southeastern United States nor have its food habits been studied well 

 elsewhere. Cottam (1939 in Palmer 1976b, Bellrose 1976) indicated that 88% of 

 the diet was composed of animals, chiefly molluscs (60.8%), crustaceans (10.3%), 

 and insects (9.6%). Studies on the wintering grounds have revealed that animal 

 foods comprise from 96% (Maine to Long Island) to 100% (New Hampshire and Massa- 

 chusetts) (authors cited iri Bellrose 1976) of the food items. 



Aside from molluscs (e.g., mussels, clams, olive shells), crustaceans 

 (e.g., barnacles, clams), and various insects (mostly aquatic forms), Surf 

 Scoters eat echinoderms (particulary Strongylocentrotus ) , marine worms, clam- 

 worms, sea anenomes, hydroids, and fish ( Ammodytes , Fundulus ) and their eggs 

 ( Clupea ) (Palmer 1976b). Judging from the few studies available, blue mussels 

 ( Mytilus edulis ), Arctic wedge clams ( Mesoderma arctatum ) , Atlantic razor clams 



372 



