370 U.S. NATIONAL MIJSETJM BULLETIN 23 7 pabt i 



flight. If one bird flew over the other's head, the second bird im- 

 mediately forgot what it had been doing and flew in pursuit. 



The flight of the black rosy finch is distinctive. Quick strokes of 

 the wings followed by a glide, seemingly with almost folded wings, 

 result in an undulating path of flight. Viewed from beneath, the 

 luster of the undersurfaces of the wings shows plainly when they are 

 in motion. 



Voice. — The black rosy finches use only three primary notes, which, 

 plus variations, serve all purposes. These birds, therefore, cannot 

 be considered as having a true song. The three call notes are: A 

 descending rather harsh chew or tsew note somewhat similar to the 

 chirping of an English sparrow, a low, throaty sharp pert, and a high 

 piercing peent. 



Flocks in flight utter a call which resembles pert-pert-chew. It is 

 heard most frequently in winter flocks and probably serves to hold 

 the group together. When the birds go to roost on a high cliff, their 

 roosting or territorial calls may be heard clearly from below even 

 when the birds cannot be seen. This call consists of a series of chew 

 notes, each one on a different pitch, uttered rapidly and continuously. 

 During the breeding season it seems to function in spacing the birds. 

 The high peent seems to serve as an alarm note, generally being 

 given when a bird is startled, and resulting in the nearby birds either 

 crouching or taking sudden flight. 



Field marks. — The distinctive coloring of this species has been 

 described under plumages and the characteristic undulating flight 

 in the section on behavior. The long pointed wings give the rosy 

 finch an appearance in flight somewhat similar to that of the moun- 

 tain bluebird, Sialia currucoides. The latter, however, does not 

 exhibit the undulating path of flight, nor does the pipit, Anthus 

 spinoletta. These two birds are the ones most likely to be mistaken 

 for rosy finches in summer. On the ground pipits walk rather than 

 hop, as the rosy finches do frequently, but the typical bobbing or 

 rocking of the pipit serves to distinguish this species. The same 

 characteristics serve to distinguish the birds in winter, with the 

 additional feature that rosy finches then occur in large flocks, fre- 

 quently numbering into the hundreds of individuals. 



Enemies. — The main enemy of the black rosy flnch is the Clark's 

 nutcracker, Nucifraga columbiana. These birds have been observed 

 destroying nests, eggs, and young of the rosy finch and have been 

 suspected of other nefarious activities (French, 1955). A long- 

 tailed weasel, Mustela frenata, was once seen carrying off a young 

 black rosy finch, with the adult bird chirping noisily over its head. 

 On another occasion two weasels were searching among the rocks of a 

 talus slope, again with rosy finches protesting nearby. This time 



