LIFE HISTORIES OF NORTH AMERICAlSr DIVING BIRDS. 131 



bird in winter is darker above than the adult and lacks the white 

 frontal plumes. This plumage is worn all through the winter and 

 often through the first nuptial season, though some mottling is ac- 

 quired on the breast during the spring and summer. In their first 

 summer plumage young birds closely resemble adults, but the bills 

 are smaller, lacking the knob, and the frontal plumes are usually 

 lacking or very small. Young birds probably do not breed until 

 their second nuptial season. At the first postnuptial molt, which is 

 complete and is prolonged through August and September, young 

 birds become indistinguishable from adults. 



The adult winter plumage resembles the first winter plumage in 

 being black above and pure white below, but the black of the upper 

 parts is not so intense, the sides of the head and neck are " plum- 

 beous " or " cinereous," and the bill is larger, with signs of the nup- 

 tial knob; the white frontal plumes are usually present in winter 

 adults and are often more pronounced than in spring. A partial 

 prenuptial molt in the spring produces the nuptial plumage with 

 the mottled under parts. 



Food. — The food of the least auklet consists mainly of amphipods 

 and small crustaceans which it obtains by diving. Among the Aleu- 

 tian Islands, I have seen them feeding a few hundred j^ards off shore 

 but often they fly way out to sea to feed. Considering that the aver- 

 age depth of Bering Sea in the vicinity of the Pribilof Islands is 

 from 30 to 50 fathoms, it hardly seems possible that these little birds 

 can dive to such great depths to obtain their food on the bottom. It 

 would seem as if they must obtain most of their food near the surface 

 or in shallower water. 



Beliavior. — The natives on St. George Island capture large num- 

 bers of least auklets for food. During the late evening hours, from 

 7 to 10 o'clock, when the birds are returning to their breeding grounds 

 in vast numbers after spending the day at sea, it is an easy matter 

 for the expert natives to catch them in nets. This custom has been 

 well described by Mr. William Palmer (1899) as follows: 



On this vast breeding range of this species, on the 28th of May, I accom- 

 panied a native for the purpose of getting a few specimens for myself, while he 

 desired a meal. With a large long-handled dip net I crouched behind one of 

 the numerous large moss and grass-bedecked rocks which so liberally covered 

 the ground. As the birds fly low and in a nearly straight line and have great 

 difficulty — in fact, they have little necessity — in making a sudden curve to avoid 

 an object, it was only necessary when a flock was seen approaching to raise the 

 net directly in their path. If the distance and their velocity had been well 

 calculated several birds would be unable to swerve off in time and in conse- 

 quence would be engulfed in the net. A quick bringing of the net to the 

 ground would then complete the capture. A half hour's work resulted in my 

 securing some 20 specimens, but the Aleut close by had ten times as many. 



55916— 19— Bull. 107 10 



