34 LIFE HISTORIES OF NORTH AMERICAN DIVING BIRDS 



duced the abundance of the species considerably, but it is probably 

 holding its own again now or perhaps even increasing where it is 

 protected. 



Fall. The fall migration starts late in August and proceeds 

 slowly. Throughout the northern portion of their breeding range 

 the birds linger until driven out of the lakes by freezing; but from 

 the southern portions of its breeding range the species never wholly 

 disappears, although the individuals seen in winter were probably 

 not bred in that vicinity. There is a coastwise movement as well as 

 a southward migration in the fall; the species winters abundantly 

 along the southern half of the California coast, as well as farther 

 south, and in the lakes of the interior. 



DISTRIBUTION 



Breeding range. Western North America. East to central Mani- 

 toba (Shoal Lake and Red River), southwestern Minnesota (Heron 

 Lake), northern Iowa (Eagle Lake, Hancock County, and Clear 

 Lake, Cerro Cordo County), and eastern Nebraska (West Point and 

 Omaha). South to southern Texas (Lavaca and Bexar Counties), 

 northern New Mexico (San Miguel and Rio Arriba Counties), 

 northern Arizona (Stoneman's and Mormon Lakes and near Flag- 

 staff), and southern California (Escondido, San Diego County). 

 West to the Sierras of California (also Bear Lake, San Bernardino 

 Mountains, and Elizabeth Lake, Los Angeles County), probably 

 eastern Oregon and eastern Washington (east of Cascade Moun- 

 tains) and south central British Columbia (Kamloops). North to 

 southern Mackenzie (Great Slave Lake). 



Winter range. Southward mainly west of the Rocky Mountains, 

 particularly along the Pacific coast. East to Nevada (Carson City) 

 and Texas (San Antonio). South to Guatemala (Lake Duenas). 

 West to the Pacific coast; western Mexico (Guaymas), Lower Cali- 

 fornia (off La Paz and Magdalena Bay) and California (entire 

 coast). North to Washington (Nisqually Flats). 



Spring migration. Northeastward starting in April. Lower Cali- 

 fornia: Colnett Bay, April 8; San Quentin Bay, May 9. Colorado: 

 Barr Lake, April 14. Wyoming: Lake Como, May 4. Nebraska: 

 End of April. Kansas: Last of April to middle of May. Missouri: 

 April 9 to May 3 (formerly). Montana: Teton County, May 1. 



Fall migration. Southwestward across the Rocky Mountains. 

 Montana: Custer and Davenport Counties, October 2. Idaho: 

 Coeur d'Alene Lakes, October 9. Colorado: El Paso County, 

 October 27. Wyoming: November 10. Missouri: September 22 

 to November 2 (formerly). Kansas: September to November, 



