YELLOW-BILLED CUCKOO 59 



At the end of seven clays the young Cuckoo resembled a porcupine more than 

 a bird. I now cut the limb holding the nest and brought it to the ground. 

 Within three feet of it I then put up the umbrella tent that I might at close 

 range observe minutely the rapid transition of the porcupine-looking object 

 into a fully feathered, beautiful Rain Crow. * * * 



The first picture was made at nine o'clock. * * * ^jiig shows the young 

 by the unhatched egg; the homy, sheathed feathers were fully two inches 

 long, making the bird look like a porcupine. About ten-thirty the sheaths 

 began to burst, and with each split a fully formed feather was liberated. 

 This process took place with such rapidity that it reminded me of the com- 

 motion in a corn popper or a rapidly blooming flower. All the while I was 

 within three feet of the bird, and could see every new feather, as it blossomed, 

 so to speak. 



At three p. m., six hours after the first picture was taken, 1 made another 

 photograph, showing this same bird in the full plumage of a Cuckoo, except 

 the long tail. 



Ill this first plumage the young cuckoo looks very much like the 

 adult, perhaps slightly paler above and with a slight wash of tawny 

 or pale buff on the throat and breast; but the tail is quite different, 

 lacking the conspicuous black and white markings so prominent on 

 the sides of the adult tail; in the young bird the dark spaces in the 

 tail are not black, but dark gray or lighter gray, variable in different 

 individuals or in different feathers in the same individual; the light 

 spaces are not so sharply defined as in the adult and are grayish 

 white instead of pure white. 



The Juvenal body plumage appears to be molted in fall, from 

 August to October; but the juvenal wings and tail are worn through 

 the first winter at least ; I have not been able to detect this plumage 

 in spring birds, so I suppose that a more or less complete molt occurs 

 while the birds are in their winter homes, producing a practically 

 adult plumage before they return in the spring. Adults have a 

 complete molt between July and October, and possibly a more or 

 less complete molt in spring before they arrive here, but winter 

 specimens to show it are lacking. 



Food. — Cuckoos are among the most useful of our birds, mainly 

 because of their fondness for caterpillars, which are some of our 

 most injurious insect pests and which constitute the principal food 

 of these birds during their seasons of abundance. Edward H. 

 Forbush (1907) writes: 



Tlie Cuckoos are of the greatest service to the farmer, by reason of their 

 well-known fondness for caterpillars, particularly the hairy species. No cater- 

 pillars are safe from the Cuckoo. It does not matter how hairy or spiny they 

 are, or how well they may be protected by webs. Often the stomach of the 

 Cuckoo will be foimd lined with a felted mass of caterpillar hairs, and some- 

 times its intestines are pierced by the spines of the noxious caterpillars that it 

 has swallowed. "Wherever caterpillar outbreaks occur we hear the calls of 

 the Cuckoos. There they stay; there they bring their newly fledged young; 



