328 BAY, SEA OR DIVING DUCKS 



flying against the wind or in stormy weather (northeast storms seem to 

 be particularly favorable for the migration of the scoters) they fly close 

 to the water and in rough weather they take advantage of the eddies 

 between the waves. The flight is usually along the seacoast, following all 

 the large indentations of the coast and crossing the smaller bays; but, 

 where considerable distance is to be gained they often fly across capes or 

 necks of land, usually all at about the same place." Gunners take advan- 

 tage of this confirmed habit and assemble at these places in large num- 

 bers to shoot at the passing flocks; "when flying against a strong south 

 wind they usually fly low enough to shoot, but, if not, a loud shout from 

 the gunners often brings them scurrying down to within range" (Bent, 

 1925). 



The food of the White-winged Scoter comes almost entirely from 

 the animal kingdom. The stomach contents of 819 of these birds, taken 

 during every month except June and September, and collected in 15 

 States, Alaska, and 5 Canadian Provinces, upon analysis gave the fol- 

 lowing approximate percentages of diet: molluscs (including rock clams, 

 14; oysters, 14, blue mussels, 12, scallops, 3), 75; crustaceans, 13; insects, 

 2; fishes, 2; miscellaneous animal food, 2; total animal food, 94 per cent. 

 Eelgrass, 2 burr reed, 1; miscellaneous plant food, 3; total plant food, 

 6 per cent. Almost every bird examined in this food study had consumed 

 some sand or gravel but in smaller volume than is the case with many 

 other waterfowl. The quantity found in reasonably full stomachs 

 ranged from a trace to about 50 per cent, yet the total averaged but 

 7.22 per cent of the stomach content. Probably a smaller quantity of this 

 abrasive material is taken because the molluscs, which are consumed 

 freely, themselves serve as effective grinding material. Pebbles as large 

 as 1 by 3^ by 14 inch, approximately, are swallowed by these birds. 

 Specific investigation at commercial shellfish beds in Massachusetts 

 showed that scallops formed about half the food of a series of White- 

 winged Scoters collected there, and a similar investigation at planted 

 oyster beds in Washington revealed that oysters were supplying a like 

 quantity. Such examples represent extreme cases, yet under such cir- 

 cumstances protective measures or control operations are imperative. 

 Fortunately these birds, along with most of the true sea ducks, feed al- 

 most entirely by day and are fairly easily driven out by the operation 

 of a motorboat equipped with loud sirens, particularly when combined 

 with a little shooting. 



The strength and degree of elasticity of the stomach of this sea-fowl 

 is surprising, and the grinding power of its gizzard is almost unbeliev- 

 able. Oysters and other molluscs are swallowed whole and many shells, 

 that require a hard blow of a hammer to break, are readily ground and 

 chemically disintegrated in the gizzard of this sea-fowl. In the gullet of 

 one bird, collected over an oyster bed, were found no less than 10 oysters, 

 one measuring over two inches in length. The remains of 46 oysters were 

 found in the gizzard of another. In the gullet of a bird collected over a 

 scallop bed were four shells, the largest being nearly 2 inches long and 



