404 BULLETIN 196, UNITED STATES NATIONAL MUSEUM 



inches, but the cavity is usually deep enough completely to conceal 

 the incubating bird. 



A. D. Henderson tells me that the ruby-crowned kinglet is an abun- 

 dant breeder at Belvedere, Alberta, "building its nest usually in a slim 

 spruce in a muskeg. The nest is very difficult to see, and is usually 

 found by watching the birds go back to it, when the female comes off 

 to feed. If the exact location of the nest is not seen, but its presence 

 is suspected, every nearby spruce is rapped with a stick; and when the 

 one with the nest is struck, the sitting female drops like a bullet to 

 within a few feet from the ground. I have seen one nest of the ruby- 

 crowned kinglet only 5 feet from the ground and another 45 feet up; 

 ten other nests ranged from 7 to 25 feet up." 



Eggs. — The ruby-crowned kinglet lays 5 to 11 tiny eggs, closely 

 packed in its little nest; sets of four are probably incomplete, from 

 seven to nine are the commonest numbers found, and any larger num- 

 bers are uncommon or very rare. The eggs are so much like those of 

 the golden-crowned kinglet that the two are practically indistinguish- 

 able. They vary in shape from ovate to oval or rounded oval. The 

 ground color is pale buffy white, dirty white, or clear white. The egg 

 is more or less evenly covered with very fine dots or small spots of 

 reddish brown or dull brown; sometimes these markings are concen- 

 trated around the larger end, and sometimes they are so faint that the 

 eggs appear immaculate. The measurements of 40 eggs average 13.7 

 by 10.8 millimeters; the eggs showing the four extremes measure 14.8 

 by 10.9, 14.0 by 11.4, 11.9 by 10.6, and 13.5 by 9.8 millimeters. 



Young. — The period of incubation does not seem to have been 

 learned, but it is probably the same as that of the European goldcrest, 

 12 days, and the young probably remain in the nest for about the same 

 length of time under normal circumstances. Incubation is apparently 

 performed wholly by the female, but both parents feed the young in 

 the nest, and for some time after they leave it. J. Dewey Soper (1920) 

 watched a pair of these kinglets feeding their young, while he was in 

 the tree near the nest and again from the top of a ladder within 3 feet 

 of it; he writes: 



During the half hour which I clung to the tree the male visited the nest with food 

 three times and the female twice. The former upon deposition of the food vacated 

 the nest promptly but the female on the contrary, often remained with the young 

 until the return of her mate, when she then slipped quietly away. In this manner 

 the young were left alone for certain periods but sheltered again for longer ones 

 when the female returned. * * * 



The detention of the female at the nest I observed, was due to her habit of 

 regularly cleaning the nest of all the sac-like excrement; due to the rapid digestion 

 of the hungry infants, her obligations in this respect seemed never to cease. The 

 matter was probed for with scrupulous care, some consumed by her, and the 

 remainder dropped overboard at some distance from the nest. In this the male 



