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.0.U. Checklist no 768—Colorado Records—Baird 54, p. 13 (S. 
arctica); 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; Gilman 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 rump, 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 E] 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 appearance to that part. 
Distribution.—Breeding in western North America, chiefly in the 
mountains 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 
