66 Birds of Colorado 
by their shorter necks, and from the Ducks by their 
reticulate tarsi; the sexes are alike and the hallux or 
hind toe is simple and not lobed. 
Key oF THE GENERA. 
A. Bill and feet always black. Branta, p. 68. 
B. Bill and feet not black, usually pink or yellow. 
a. Depth of bill at base more than the length of the culmen; 
plumage mainly white. Chen, p. 66. 
b. Depth of bill at base less than half the culmen; plumage 
never mainly white. Anser, p. 68. 
Genus CHEN. 
Bill about equal to the head, high at the base, its depth there more 
than half the length of the culmen; serrations on the cutting-edge 
of the upper mandible prominent, large and fully exposed ; plumage 
chiefly white, or white and grey; bill and feet red. 
Four species, chiefly in the Arctic regions of the Northern Hemisphere. 
Key oF THE SPECIES. 
A. Outline of the frontal feathering forming « convex line at the 
base of the bill. 
a. Larger; wing over 17. C. h. nivalis, p. 67. 
b. Smaller; wing under 17. C. hyperboreus, p. 66. 
B. Outline of the frontal feathering nearly straight; size still 
smaller, wing about 14:5. C. rossi, p. 67 
Snow-Goose. Chen hyperboreus. 
A.O.U. Checklist no 169—Colorado Records—Henshaw 75, p. 470; 
Thorne 87, p. 264; Morrison 89, p. 165; Cooke 97, pp. 18, 58, 196; 
06, p. 65; Henderson 03, p. 234; 09, p. 226; Rockwell 08, p. 158. 
Description. Adult—Pure white except the wing, the tips of which 
are black and the bases grey; head often stained with rusty-brown ; 
iris dark brown, bill dull red with a white tip and black along the 
cutting-edge; legs dull pink. Length 25-0; wing 17-0 or less; tail 
5-5; culmen 2-3; tarsus 3-1. 
Young birds have the top of the head and upper-parts light grey, 
and the bill and feet dark. 
Distribution.—Breeding on the Arctic coasts of the Mackenzie 
Province and probably in north-east Asia; wintering from the Mis- 
sissippi Valley to California and south to central Mexico; in Asia 
to Japan. 
