614 ANIMAL LIFE IN THE YO SEMITE 



liver from a pile of discarded mammal bodies and had carried this material 

 to the youngster as food. When the young bird had swallowed as much 

 of the liver as it could hold, a portion still protruding from its mouth. 

 The parent, in haste to clean the nest, had picked up the free end of the 

 piece of Hver, not appreciating the fact that the youngster had swallowed 

 the other end, and had carried both the liver and the young robin out 

 of the nest. 



Mr, Donald D. McLean has recorded (1919, p. 160) the finding of 

 remains of six Western Robins in the stomach of one female California 

 Wildcat killed by him March 10, 1919, near Coulterville. At Chinquapin 

 on May 20, 1919, a robin was seen flying at a Sierra Chickaree, snapping 

 its beak loudly, until it forced the squirrel to descend the tree. The evidence 

 is only circumstantial, but might indicate that the squirrel had invaded 

 the robin's nesting precincts. Much further and careful observation must 

 be made before the enemies of the robin are well known. 



Toward the latter part of June, 1920, in Yosemite Valley, at least 

 four young robins were picked up in which the plumage was oil-soaked, 

 evidently as a result of the birds having bathed in pools of water upon 

 which oil had been sprayed to kill mosquito larvae. One of these birds 

 was nearly dead ; the others were obviously not in normal condition. Here, 

 then, is another way in which man's activities interfere with the course 

 of events in nature. 



Partial albinism is not an uncommon phenomenon in the Western 

 Robin. Two instances came to our attention in the Yosemite region, in 

 both of which the birds in question had some white feathers on the head. 

 Complete albinos are much rarer, as are melanos (abnormally dark colored 

 individuals). In a bird of the size and habits of the robin, abnormalities 

 in coloration are much more likely to be observed and commented upon 

 than are similar occurrences among the smaller and more retiring species. 

 In any event, albinism is merely the outward physical manifestation of 

 some defect, local or general, in the tissues or body processes of the animal 

 in which it occurs, and does not warrant the attention which has been 

 directed to the subject by some scientific as well as many lay students. 



Northern Varied Thrush. Ixoreus naevius meruloides (Swainson) 



Field characters. — Size of Robin and somewhat similar in coloration, but with a 

 black, or (in female) slaty, band across chest, and a shorter tail. Upper surface slato- 

 colored ; under surface bright rusty brown (more orange than in Robin) ; conspicuous 

 stripe of same color behind eye; also bars and spots of same on wing. In flight like 

 Robin, but with a pale band showing lengthwise of each spread wing. Voice: Call note 

 a single, not loud, deep, staccato chuck; song a slowly uttered series of weird syllables, 

 successively on different pitches, now low, now high; each note intoned from one to 

 three seconds: zurrrrr. 



