522 U.S. NATIONAL MUSEUM BULLETIN 2 37 pakt i 



Earlier they write: 



"The foundation of the nest was of twigs of conifers. The super- 

 structure was of fibrous material stripped from plant stems, a few 

 grass blades, several pieces of herbaceous plant stems, a small tuft 

 of hair, and a fascicle of pine needles (Pinus flexilis) . The lining was 

 of shredded bark, lichens, and fine hair (no feathers so far as we could 

 see). The nest measured (after collection) 107-123 mm. in over-all 

 diameter, 52 mm. in over-all depth. The cup proper was 60 mm. 

 wide and 27 mm. deep." 



A. Lang Baily wrote Mr. Bent that numbers nested on Genesee 

 Mountain, 20 miles west of Denver, commencing Dec. 20, 1951. 

 Nesting was still in progress when he wrote on June 6, 1952. Of 14 

 nests known to have complete sets of eggs, three nests held four eggs, 

 each; nine nests held three eggs each; and two nests held two eggs 

 each. Egg measurements varied from 22.6 X 16.4 to 21.3 X 16.2 

 millimeters, averaging 21.95 X 16.26. There was evident color 

 variation. 



Later, Baily (Bailey, A. M., Baily, A. Lang, and Niedrach, R. J., 

 1953) published a full account of this nesting colony, which may be 

 summarized briefly: Nesting began in late December in the yellow 

 pine (Pinus ponderosa) stands in the foothills and slowly moved up- 

 slope, reaching the Hudsonian zone by midsummer. Territoriality 

 was observed only at the time of nest site selection. Females took 

 the leading role in nest site selection and nest construction. The 

 total time involved in nesting, from start of construction to fledging, 

 was from 43 to 48 days: nest construction, 5 days; completion of nest 

 to laying of fu'st egg, 4 to 5 days; egg laying at one per day, 2 to 4 

 days; incubation, 14 days; nestling period, 18 to 20 days. Clutches 

 averaged 3, varying from 2 to 4. Only females incubated. Strong 

 evidence of double nesting was found. One nest was used for a second 

 set of eggs after the first set was destroyed. Nesting success averaged 

 one bird fledged for every three eggs laid. 



Plumages. — H. B. Tordoff (1952) shows that the first winter plum- 

 age of male benti is fully as red as adult male winter plumage, benti 

 differing in this respect from the eastern North American and Old 

 World subspecies. In first winter plumage, young birds can be dis- 

 tinguished by the color of the edgings of certain flight feathers (red 

 in adults, yellowish in immatures). He also demonstrated that 

 benti (and probably other subspecies) has a distinct, although limited, 

 prenuptial molt involving the chin, throat, and to a lesser degree the 

 rest of the head. In northeastern Kansas, where his studies were 

 made, the feathers produced by this prenuptial molt lack red pigment 

 in the males. He suggested that the failure to develop red pig- 

 ment might be based on hormonal balance of the birds at the time 



