LIFE AND BEHAVIOK OF THE CUCKOO 
233 
5. The American black-billed cuckoo is born with rudimentary 
down, which never unfolds. It has strong grasping reflexes, and 
is remarkably enduring. It can hold by one leg or toe, for a sur- 
prising length of time, and draw^ itself up to the perch with one or 
both feet, at birth or shortly after, powers which no other birds 
in this part of the world are known to display, and which must be 
regarded as preparatory to the climbing stage soon to follow. 
6. On the sixth day the complete quill stage is reached, when 
the bird bristles with feather-tubes, which bear at their apices the 
white hair-like tubes of the down. The preening instinct has then 
asserted itself, and the horny cases of the feather-tubes, giving 
way to their bases, are rapidly combed off by the bill over the 
greater part of the body. The wing- and tail-quills, as well as 
some of the contour-feathers are released in the usual way, cen- 
tripetally from their tips. 
7. Fear is attuned to the climbing stage, and not to that of 
flight as in all the common altricious birds, and matures with com- 
parative suddenness on the sixth day, or shortly before^ the bird 
is ready to climb. 
8. l^arental instincts are as strong in the American cuckoos as in 
thrushesorin passerine birds generally, and there is no more indica- 
tion of a retrogression to parasitism in the former than in the latter. 
9. The nests of these cuckoos, though slight, are well adapted 
to their purposes, and often long outlast their us(\ 
10. When disturbed in its nest-activities, the black-hill has 
been known to transfer its eggs to a new nest of its own, an action 
which strongly suggests the practice of the European cuckoo of 
carrying its laid egg in bill to the nest of a nurse. 
11. The American species occasionally ^exchange' eggs, or 
lay in other birds' nests, and when so doing the black-bill has been 
known to struggle for possession of the stolen nest. Since similar 
actions have been repeatedly observed in one or another degree, 
in numerous species, in which no suspicion of parasitism exists, 
and in all parts of the world, they must be ascribed, in addition 
to the reasons given above, not to "stupidity or inadvertance," 
orito "si tendency towards parasitism," but to temporary irregu- 
larities in the rhA^thms of the reproductive cycle. 
THK JOtTRN VI. OK KX 1' KKl M K.NTAI. ZOOLOGY, VOI . 9., NO. 1. 
