Mountain-Bluebird 529 



The nest is placed in old Woodpeckers' and other 

 holes, or sometimes between a slab of bark and the trunk 

 of a dead pine tree, or in nesting-boxes if provided, 

 and the eggs, four or five in number, are pale blueish. 

 Fresh eggs are to be met with about the end of May or 

 beginning of June. 



Mountain-Bluebird. Sialia currucoides. 



A.O.U. Checklist no 768— Colorado Records — Baird 54, p. 13 {S. 

 arcfica) ; Allen 72, pp. 148 155, 161 ; Aiken 72, p. 194 ; Trippe 74, 

 p. 229 ; Henshaw 75, p. 162 ; Scott 79, p. 91 ; Minot 80, p. 225 ; 

 Tresz 81, p. 284; Drew 81, p. 86 ; 85, p. 15 ; Allen & Brewster 83, 

 p. 153 ; Beckham 85, p. 140 ; 87, p. 125 ; Morrison 86, p. 153 ; 88, p. 71 ; 

 Kellogg 90, p. 90; Dille 94, p. 36; 03, p. 74; Lowe 94, p. 270; 01, 

 p. 276 ; McGregor 97, p. 39 ; Cooke 97, pp. 18, 126, 223 ; Keyser 

 02, p. 98 ; Henderson 03, p. 237 ; 09, p. 242 ; Gihnan 07, p. 195 ; 

 Warren 08, p. 26 ; 09, p. 17 ; Rockwell 08, p. 180 ; Cary 09, p. 185. 



Description. — Male — Above bright blue of a turquoise shade, lighter 

 than that of the other two species, becoming dusky on the tips and 

 inner webs of the longer wing-feathers ; below blue, paler and less 

 bright than above, paling to white on the abdomen and under tail- 

 coverts ; iris dark brown, bill and legs black. Length 6-25 ; wing 

 4-5 ; tail 2-75 ; culmen -45 ; tarsus -78. 



The female is much duller than the male ; upper-parts greyish- 

 blue, becoming rather a brighter blue on the rximp, wings and tail ; 

 no white on the outer web of the outer primary ; a white orbital ring ; 

 below brownish-grey, a little buffy on the throat, paling on the abdomen 

 and under tail-coverts to dull white ; a little smaller than the male — 

 wing 4-35. In winter the male is duller in colour, the blue being 

 obscured by the brownish tips to the feathers above and below ; early 

 arrivals in El Paso co. in March show this plumage. Young birds are 

 ashy-brown above, the interscapular area spotted with white ; rump 

 and upper tail-coverts light ashy ; below dull white ; the feathers of 

 the throat and breast broadly edged with brown, giving a strongly 

 squamated appeaxance to that part. 



Distribution. — Breeding in western North America, chiefly in the 

 motintains from Yukon to Chihuahua in northern Mexico, east to south 

 Dakota and Texas, west to California ; wintering in the southern 

 portion of the breeding range and at lower elevations. 



This is far the most abundant of the Bluebirds in Colorado ; it 

 arrives from the south normally in the middle of March, and is found 

 nesting everywhere from the plains to timber line. A warm spell 



LL 



