354 U.S. NATIONAL MUSEUM BULLETIN 237 taut i 



Young. — Shaw (1936) inferred from his studies that the incubation 

 period is about 14 days. Of four helpless young rosy finches he says: 

 "Tender skin was noticed, irregularly tufted with fluffy gray down, 

 which moved in the breeze. Large, dark, closed eyes, — yellow- 

 rimmed mouths, thin, wobbly necks through which pulsed spurts of 

 warm blood from strong heart to brain, all showing most vividly 

 when the birds were brought from their hidden retreat to open day- 

 light. No sound was uttered. Every effort was made by the fledg- 

 lings to hide the eyes from the light." 



When 6 days old the young "weighed 56 grams for the four of 

 them, or 14 grams apiece. They still retained the gray downy plum- 

 age of hatching; but now had in addition, blackish pterylae of pin- 

 feathers and stubby wing and tail quills. The eyes of one or two of 

 them were just faintly opening and they had tiny far-away voices, 

 rarely used, at long intervals." 



At 9 days of age, "they had advanced markedly and weighed 84 

 gi*ams, or an average of 21 grams apiece. They were now showing 

 distinct signs of intelligent, awakening interest. Hunger seemed to 

 be a rather constant stimulus. Baby down was now giving way to 

 rather coarser resistant feathers. Eyes were all open, as also were 

 gaping yellow-rimmed mouths on sUghtest provocation." 



At 14 days of age, the young were beginning to leave the nest. 

 One of the remaining two weighed 26 grams. "The following day 

 no birds, young or old remained. The Rosy Finches had abandoned 

 their glacier nesting places for the more congenial and fruitful for- 

 aging sites beside the moist edges of the retreating snow banks of 

 the flower-clothed moraines." 



Plumages. — The molts and plumages are apparently similar in all 

 the rosy finches. The plumages are well described under the brown- 

 capped rosy finch, but there is too little material available for a study 

 of the molts. 



Food. — Rosy finches are mainly ground feeders, picldng up the 

 seeds of weeds and wild plants. The Leffingwells (1931) made a 

 study of the winter habits of Hepburn's rosy finch at Clarkston, 

 Wash., and "found that 99 percent of the food consists of the seeds 

 of weeds found abundantly on the steep slopes of the canon walls or 

 in the wheat fields on the tops of the bluffs, while but one percent was 

 insect material. The seeds most commonly taken are Russian thistle, 

 Salsola kali] wild grass, Sporoholus cryptandrus', Jim Hill mustard. 

 Sisymbrium altissimum; and sunflower, Helianthus annuus." They 

 list six other species of plants of which the seeds are eaten. 



They also mention that the summer food of both adults and young 

 consists more largely of insect food; in 16 birds, collected by Swarth 



