FAMILY ALCIDA.— AUKS, PUFFINS, AND MURRES. 29 
Back, with white spots ; throat, white or whitish (immature or winter). 
Gavia lumme. Red=throated Loon. 
See No. 7. 
Back, without distinct white spots; the feathers, edged with ashy: throat, white or 
dusky (immature or winter). Gavia arcticus. Black-throated Loon. 
see No. 6. 
* Group 3. Wing, over 15 inches long. 
Feet, webbed; head, black, in adult; head, gray; throat, whitish, in immature. 
Urinator imber. Loon. 
See No. 5. 
FAMILY ALCID-. 
Auks, Puffins, and Murres. 
Toes, three; no hind toe (hallux); toes, palmate (full 
webbed) ; nostrils, separate, and not tubular. 
* Group |. Wing, less than 5 inches long. 
Winter plumage: Upper parts, black; underparts, white. Jn swimmer: Vhe 
breast, throat, and sides of the head and neck, sooty brown. 
Alle alle. Dovekie. Little Auk. 
See No. 17. ce eer S 
* Group 2. Wing, 5.50 to 6.50 inches long. 
Bill, parrot like; underparts, white; back, black; usually a black 
collar. Fratercula arctica. Puffin. Sea Parrot. 
See No. 9. 
Adult in summer: General plumage, black, a white patch on 
the shoulder; basal half of the greater wing coverts (feathers 
forming the white patch on the wing), black. Winter birds have 
the underparts white, and the upper parts, black and white. 
Cepphus grylle. Black Guillemot. Sea Pigeon. 
See No. 11. 
Similar to Black Guillemot, but has the wing coverts (feathers forming the white wing 
patch) entirely white and not with basal half black. 
Immature and winter birds (except wing coverts), resembling the Black Guillemot. 
Cepphus mandtii. Mandt’s Guillemot. 
See No. 12. 
* For directions for measurement, sce page 9, 
