336 BAY, SEA OR DIVING DUCKS 



its daily pursuit of food and to escape from its enemies in emergencies. 

 It dives with an awkward splash, but very quickly and effectively, open- 

 ing its wings as it goes under, and using them in its subaqueous flight. It 

 can remain under for a long time and swim for a long distance without 

 coming up; it is useless to attempt to chase a slightly wounded bird" 

 (Bent, 1925). As a rule scoters dislike flying over land and usually follow 

 the coast line. When they do encounter a bold cape they are evidently 

 at a loss. Sometimes they will turn one way, then another, and either 

 decide to follow the shore around the cape, increase their elevation to a 

 considerable height and fly over the cape, or turn back and settle in the 

 water as though to decide what course to pursue. It is characteristic of 

 the flight of these scoters that an audible, deep whistling of the wings ac- 

 companies the few beats of the wings just as the bird alights on, or 

 rises from the water, and that it holds its wings extended upward for a 

 short interval after alighting. 



As their name implies, these birds are adepts in diving through the 

 breaking surf. Mrs. Bailey (1916) describes their ability in this regard 

 as follows: "It was a pretty sight when, under a gray sky, the beautiful 

 long green rolls of surf rose and combed over and the Surf Scoters came 

 in the from the green swells behind to feed in front of the surf and do 

 skillful diving stunts to escape being pounded by the white waterfalls. 

 As the green wall ridged up over their heads they would sit unmoved, 

 but just as the white line of foam began to appear along the crest they 

 would dive, staying under till the surf had broken and the water was 

 level again. When diving through the green rollers near the shore the 

 black bodies of the scoters, paddling feet and all, showed as plainly as 

 beetles in yellow amber." 



Nearly nine-tenths of the food of this duck is from the animal king- 

 dom. One hundred sixty-eight adults were collected in 13 States, Alaska, 

 and 7 Canadian Provinces, in every month of the year, and an analysis 

 of the stomachs gave the following approximate percentages of diet: 

 molluscs (including the blue mussel, 29), 61; crustaceans, 10; insects, 10; 

 fishes, 3; miscellaneous animal food, 4; total animal food, 88 per cent. 

 Pondweeds, 3; miscellaneous plant food, 9; total plant food, 12 per cent. 

 Gravel averaged about 18 per cent of the total stomach volume. An anal- 

 ysis of the stomach contents of seven juveniles collected in July and 

 August showed that young birds consumed six times as many insects, 

 less than one-third as many molluscs and nearly twice as much plant food 

 as the adults; this modified diet no doubt accounts for the greater palata- 

 bility of the flesh of juveniles. Many of the stomachs of the adult birds 

 were collected during an investigation to determine the extent of their 

 depredations on the commercial shellfish beds off the coast of Massa- 

 chusetts; neither oysters nor scallops were taken to any extent and it was 

 established that the Surf Scoter cannot be considered a serious menace 

 to the shellfish industry. Both the White-winged Scoter and the Ameri- 

 can Scoter indulge in these choice molluscs to a far greater extent than 

 does this species. 



