BLACK ROSY FINCH 371 



their search was unsuccessful. In most cases the young birds are 

 susceptible to the predations of these or other mammals for only a 

 brief period, just after leaving the nest. 



In a nest in the Absaroka Range of Wyoming the nesthng black 

 rosy finches were infested with blood-sucking larvae of a fiy, later 

 identified as belonging to the genus Protocalliphora. The harm result- 

 ing to the young birds could not be determined. They at least 

 survived to the time of leaving the nest. 



Fall. — The rosy finches start to flock in the high mountains by the 

 time the young birds become independent of the parents. These 

 flocks coalesce until they may be composed of several hundred indi- 

 viduals. These hardy birds remain at high elevations until well 

 after freezing weather sets in, where they have been seen regularly 

 throughout October and as late as November 2 in the Uinta Mountains 

 and the Wasatch Mountains of Utah. At about this time the birds 

 begin to appear in the valleys and deserts at lower elevations and 

 start using their winter roosts in these areas. The exact paths and 

 distances involved in the migration are not yet known, but a com- 

 parison of the summer and winter ranges indicates that the birds 

 probably move about 300 miles and several thousand feet in altitude in 

 the process. 



Winter. — The winter range of the black rosy finch includes Utah, 

 the southern half of Wyoming, and the western half of Colorado. 

 The species has been reported in adjacent parts of Arizona, in Nevada, 

 and even in extreme eastern California. These and the other rosy 

 finches have communal winter roosts which they use year after year. 

 Where the winter ranges of two or more kinds of rosy finches overlap, 

 these birds will occur in mixed flocks that will use the same roosts. 

 At a cave in Bingham County in southeastern Idaho, gray-crowned 

 rosy finches, L. t. tephrocotis, and Hepburn's rosy finches, L. t. littoralis, 

 regularly may be found roosting together in winter. In southwestern 

 Wyoming and throughout Utah the black rosy finch occurs with these 

 two, and in central and southern Colorado a fourth, the brown-capped 

 rosy finch, L. australis, joins the winter flocks. 



The winter roosts provide overhead shelter and escape from the 

 wind. Known roosts are few, but those that have been observed 

 include cave entrances, mine shafts, abandoned cliff swallow nests, 

 and such man-made structures as piers, out-buildings, and barns. 

 The birds leave the roosts at daybreak to forage in surrounding areas 

 and return by midafternoon. Although feeding flocks met with 

 during the day are large, the birds seem to return to the roost in small 

 groups. The birds settle on their individual perches within the dimly 

 lighted cave or structure well before sundown. 



646-737— 68~pt. 1 26 



