302 Birds of Colorado 
Genus MOLOTHRUS. 
Small birds—wing under 4-5—with a short, conical bill and small. 
rounded nostrils ; wing long and pointed, with the eighth to sixth pri- 
maries sinuated on the outer web ; tail about % the length of the wing, 
even or slightly forked; tarsus a little longer than the middle toe 
and claw; the claws short and curved ; plumage chiefly glossy black 
and brown. 
This genus contains the Cow-birds, many of which are parasitic in 
habit, laying their eggs in the nests of other birds. They are found 
throughout temperate and tropical America, and a number of species 
have been described ; only the common North American form is found 
in Colorado. 
Cow-bird. Molothrus ater. 
A.O.U. Checklist no 495—Colorado Records—Allen 72 pp. 150, 157 
(Molothrus pecoris); Aiken 72, p. 202; Henshaw 75, p. 312; Tresz 81, 
p. 94; Allen & Brewster 83, p. 192; Drew 85, p. 16; Beckham 85, 
p. 142; Morrison 89, p. 148; Lowe 92, p. 101; Bendire 92, p. 434; 
95, pp. 587-597; Cooke 97, pp. 93, 211; Henderson 03, p. 236; 
09, p. 234; Dille 03, p. 74; Warren 06, p. 22; Markman 07, p. 157; 
Gilman 07, p. 156; Rockwell 08, p. 169; Warren 08, p. 22; 09, p. 15. 
Description.—Male—General colour above and below black, with 
metallic purplish gloss ; head, neck and chest all round sepia-brown ; 
iris brown, bill and legs black. Length 7-5; wing 4:5; tail 3-10 
culmen -65; tarsus 1-0. 
The female is smaller (wing 4-1) and dusky greyish-brown in colour, 
rather paler below, marked with darker centres and blackish shaft- 
streaks especially above ; the chin nearly white; bill brownish. The 
young birds are rather duller than the adults and more variegated, 
with paler margins and darker centres to the feathers. 
Distribution.—Breeding throughout the United States, except Florida, 
and the southern portions of the Dominion to the Mexican border and 
the Pacific coast ; south in winter to central and south-eastern Mexico 
In Colorado the Cow-bird is a fairly common summer resident in the 
eastern foothills region and plains from Larimer co. (Markman), 
through El Paso co. (Aiken), to Baca co. (Warren); it passes up in 
the mountain parks to an elevation of about 7,000 to 8,000 feet, having 
been found breeding in both Middle and South Parks by Carter (Cooke) ; 
it is reported from La Plata co. in spring (Gilman) and is common in 
Mesa co. (Rockwell), and in Routt and Grand cos. (Warren). It 
arrives from the south about the end of March, and departs again 
about the end of September. 
Habits. — The Cow-bird is gregarious, polyandrous 
and parasitic in its habits ; after arrival from the south 
