CASSIN'S AUKLET 113 



and if tossed into the air they descend quickly and hide themselves from the 

 light. They commenced flying this year as early as April 2, and eggs have 

 been found as late as November 20, showing a breeding time extending through 

 eight months. 



Mr. A. W. Anthony, in his notes sent to Major Bendire, refers to 

 a nest "containing a nearly fledged young and an adult female in- 

 cubating a fresh egg; the fledgling was crowded into a branch burrow 

 away from the main nest." Mr. W. Otto Emerson, in his notes, 

 states that two or three broods are raised and that he has found 

 fully grown young in the same hole with the parent bird sitting on 

 the second laying. Possibly in all of these cases the young bird 

 and the egg may have belonged to different parents, but this hardly 

 seems likely, unless the young bird may have been sufficiently fright- 

 ened by the process of opening the burrow to have run into a com- 

 partment occupied by an incubating bird. If this bird is such a 

 prolific breeder as it seems to be this would account for its great 

 abundance over such a wide breeding range. 



Young. Mr. Emerson gives the period of incubation as 21 days 

 and Mr. Littlejohn as 30 days. The chick remains in the nest and is 

 fed by its parents on regurgitated food until it is fully fledged and 

 able to fly. Mr. Emerson says that the young are fed in the same 

 manner that a pigeon feeds its young, the parent throwing up a 

 thick, creamy, chocolate-colored matter, containing what he took to 

 be small marine insects. He says that the young become "rolling fat 

 while in their holes and the old birds are never poor from the cares 

 of incubation." The young remain in the burrows until able to fly. 



Plumages. The downy young is "blackish brown" or "fuscous 

 black" when first hatched, fading to "fuscous" or "hair brown" 

 when older, on the upper parts; the throat, breast, and flanks are 

 paler; and the belly is "ecru drab," "drab gray," or "drab." Ac- 

 cording to Mr. Howell's observations, "pin feathers begin to show at 

 the base of the down when the chick is but 2 or 3 days old. They 

 first show through on the underparts, then on the head, and the 

 down gradually is shed from the end of the feathers until a small 

 tuft below the chin is all that remains." The first plumage, which 

 is thus acquired directly from the downy stage, is not strikingly 

 different from that of the adult. The bill is decidedly smaller, how- 

 ever, the throat is whiter and the wings and tails are browner in 

 young birds. The first nuptial plumage shows no very marked 

 change and the young bird closely resembles the adult; birds with 

 smaller bills and slightly whitish throats are probably young birds. 

 Adults have no conspicuous seasonal changes of plumage, except 

 that the fall plumage looks brighter and fresher. The clear, slaty- 

 blue and black plumage of adults in the fall, together with the larger 

 bills, will usually serve to distinguish them from young birds. 



