58 BULLETIN 17 6, UNITED STATES NATIONAL MUSEUM 



cry. It fluttered along when I approached, but it could not fly from 

 that position, in rather long grass, though wings and tail were 

 pretty well fledged. When I picked it up, it pecked at my finger 

 angrily. It seemed as fierce as a young hawk, and its rasping cry was 

 probably calculated to inspire terror in its enemies. I placed the 

 bird on a bough of a Norway spruce, where it took a characteristic 

 cuckoo attitude and seemed much more at home than on the ground." 



Dr. Lawrence H. Walkinshaw has sent me some notes on the 

 weights and development of young yellow-billed cuckoos. One 

 "well-grown" young was weighed for three days in succession before 

 it left the nest, at 6 a. m. each morning. It weighed 28.8 grams the 

 first morning, 31 grams the second, and only 26 grams on the third, 

 August 6. The interesting point is that the loss of weight came with 

 the sudden development of the plumage, of which he says : "Wlien I 

 visited the nest on August 5, at 6 a. m., his feathers resembled the 

 quills of a porcupine, long and bluish, stretched out over his wings 

 and back. At 7 p. m., these quills had all opened and the bird had 

 taken on the resemblance of an adult cuckoo. Correspondingly, the 

 following morning, he had lost 5 grams in weight. He left the 

 nest on August 6." 



At another nest a young bird weighed 25 grams on August 25, 

 27.6 on the 26th, 32.9 on the 27th, and only 28.9 grams on the 28th ; 

 this bird left the nest on August 29, with feathers unsheathed. He 

 says that during the unsheathing process the young bird dressed its 

 feathers continually; "the wings, the tail, the scapulars, the rump, 

 and breast all shared alike, then with the feet he would work about 

 the head and throat. Wlien hungry he would pause and call a low 

 cuk-cuk-cuk-cur-r-r-r-rrr. If the parent did not come soon, these 

 calls increased in number. "While feeding, his wings would vibrate 

 rapidly, and after the parent left his call was more of contentment, 

 a short curr, or a cuk-ctinTrr. When excreting, he simply backed 

 up to the edge of the nest." 



Plumages. — Bendire (1895) says: "The young when first hatched 

 are repulsive, black, and greasy-looking creatures, nearly naked, and 

 the sprouting quills only add to their general ugliness." This is a 

 very good description, and the young birds do not improve much 

 in appearance during the period of early growth. The body is well 

 covered with the long, pointed feather sheaths until the young bird 

 is more than half grown. But the sheaths burst, the juvenal plum- 

 age appears, and the young bird is well feathered before the time 

 comes to leave the nest. 



Dr. A. H, Cordier (1923) describes this process very well as 

 follows : 



