348 Birds of Colorado 
Aiken found one in a willow at Limon, on the plains. 
It is a somewhat flat structure, formed of twigs and root- 
lets and well lined with fine rootlets and hairs; the 
eggs, three or four in number, are pale bluish-green, 
speckled chiefly at the larger end with rusty-brown. 
They measure about ‘65 x °45. 
Dille states that the Siskin nests in the lilac bushes 
in the Denver suburbs ; he found three eggs laid between 
May 13th and 17th. 
Genus PASSER. 
Rather small birds with a stout and deep bill in which the lines of 
the culmen and the gonys are slightly convex, and the upper mandible 
is slightly deeper than the lower ; nostrils concealed by the nasal plumes ; 
wing moderately pointed, the difference between the primaries and 
secondaries about equal to the tarsus; tail about -75 the length of 
wing, nearly even; plumage without red or yellow; wings white 
barred. 
The genus is by nature confined to the Old World. Two species have 
been introduced and one has spread over the greater part of North 
America ; the other, the European Tree-Sparrow, seems to be confined 
to the neighbourhood of St. Louis, Mo. 
English Sparrow. Passer domesticus. 
Colorado Records—Lowe 95, p. 99; Cooke 97, pp. 99, 165, 213; 
Keyser 02, p. 127; Henderson 03, p. 236; 09, p. 236; Warren 06, 
p. 22; 08, p. 23; 09, p. 16; Gilman 07, p. 156 ; Markman 07, p. 157; 
Rockwell 08, p. 171. 
Description.—Male—Crown dark grey bordered on either side by a 
triangular postocular patch of dark chestnut; back rufous-chestnut, 
striped with black ; rump grey; wings and tail dusky, with chestnut 
edgings and tips, middle-coverts tipped with white; below ashy, 
becoming white on the centre; a black patch covering the chin, throat 
and upper-breast; bill black, feet horn-brown. Length 5-5; wing 
3-0; tail 2-25; culmen -5; tarsus -70. 
The female has the crown and postocular region greyish-brown or 
olive, no black on the throat and is less brightly coloured; bill 
horny-brown. Young birds are like the female but soon acquire 
the dusky throat. 
Distribution.—Europe, except Italy; introduced into America, 
Australia and many other parts of the world and thoroughly naturalized. 
Said to have been first brought to Portland, Maine, in 1858 ; established 
