1068 U.S. NATIONAL MUSEUM BULLETIN 23 7 paet 2 



* * *." He adds that severe weather at a critical period in the life 

 cycle increases chances of predation. 



Fall. — With family cares behind them, as fall approaches the 

 jimcos start gathering in flocks to forage together on the matured 

 seeds that are plentiful and readily available in most of the country- 

 side. I believe Oregon jimcos that summer in the high mountains 

 of our western states stay in the mountains until fall storms drive 

 them down. With the first hard snow, which can come in early 

 October in the high country, the jimcos quickly move to lower ele- 

 vations or leave altogether. The fall migration may involve long 

 flights for many shufeldti and montanus. For many thurberi the fall 

 migration is merely a withdrawal from the high Sierra to adjacent 

 foothills and vaUeys. 



Migrating juncos may be found in a wide variety of habitat: edges 

 of chaparral, fence rows bordering farm and ranch lands, juniper 

 (Juniperus utahensis or J. scopulorum) and pinon (Pinus edulis) 

 woodland, sagebrush {Artemisia tridentata) , city cemeteries, brush 

 tangles, riparian plant growth along streams, suburban yards, or- 

 chards, and country roads with weed- or brush-covered rights-of-way. 

 Here again, the "edge" effect appears to be overwhelmingly attrac- 

 tive to migrating jimcos. They prefer habitats consisting of some tree 

 or bush cover adjoining patches of open ground. Presence or absence 

 of snow affects their movements. Juncos usually desert parts of the 

 country subject to heavy or prolonged sno\\^all, except for a few 

 individuals held by artificial feeding or those able to peck out a living 

 around a barnyard. 



Winter. — Oregon juncos of the three races discussed in this account 

 commonly occur in winter in the lower mountains of Colorado, New 

 Mexico, and Arizona, on the great plains adjacent to the Rocky 

 Mountains, the coastal and lowlands of Oregon, Washington, and 

 California, the interior valleys and foothills of California, suitable 

 places in the Nevada and Arizona deserts, similar locations in other 

 western states, and at lower elevations within the breeding ranges 

 of some of the forms as far north as British Columbia. Oregon jimcos 

 of different races become thoroughly intermingled in the winter flocks, 

 and according to Winifred S. Sabine (1955) the same winter flock 

 may contain both local and migrant individuals. 



C. F. Batchelder (1885) writes about wintering jimcos he saw near 

 Las Vegas Hot Springs, San Miguel County, N. Mex., in December 

 1882: 



Passing the various hot springs that come boiling to the surface at numerous 

 points along the stream, a short walk up the canon brings you to one of the 

 openings where the retreating hills leave a level stretch of a few acres. Among 

 the thick clumps of low scrub oaks that are scattered over it, or in the large 

 patches of tall dead weeds, I was siu-e to find companies of Jimcos (Junco oreqonus 



