NUTCRACKEB 



395 



on April 30, 1916, a pair of adult nutcrackers was seen foraging in some 

 willows, and near Walker Lake on May 9 of that year another pair was 

 encountered. In each case the headquarters of the birds were likely on 

 the higher east face of the Sierras close by. During a visit to the upper 

 margin of the forest on Mono Craters on June 10, 1916, at least four 

 family parties all containing fully fledged young were observed. The 

 young birds were following their parents about and begging assiduously 

 for food. Whether or not these families were reared in the immediate 

 \icinity is problematical. Adult birds collected in Lyell Caiion in mid- 

 Jnly showed by dissection that the breeding season was long passed. It 

 may be safely inferred that the pairs of adults seen by themselves in April 



Fig. 49. Head of Clark Nutcracker, showing protecting "mask" of feathers which 

 serves to keep snow and other foreign materials out of nostrils. Natural size. 



and early May had eggs or young, more likely the latter. All of this 

 evidence points to nest building as beginning in the Yosemite region in 

 March or early April. 



The staple article of diet of the Clark Nutcracker seems to be pine 

 nuts. An adult female shot on Williams Butte, September 22, 1915, held 

 in its throat 72 ripe seeds of the piilon, comprising a volume of about one 

 cubic inch. Another female taken September 25 of the same year on 

 Warren Fork of Leevining Creek held in her distended throat 65 mature 

 seeds of the white-bark pine, and some fragments, all together weighing 

 10 grams or close to 7 per cent of the weight of the bird, which was 146 

 grams. The nutcrackers on the east side of the mountains often descend 

 to the slopes where piilons are abundant, and the nuts of that tree are 

 known to be a favorite food in many localities elsewhere in its range. 

 During at least a part of the year, however, this vegetarian diet is varied 



