BLACK-HEADED GEOSBEAK 485 



There is probably no species of bird better known to summer visitors 

 to the Yosemite Valley than the black-headed grosbeak. This is the bird 

 Avhich is wont to fly dowTi from the trees surrounding a camp and pilfer 

 viands, especially butter, from the dinner table. Indeed so well has this 

 trait been developed among the grosbeaks in Yosemite that they have been 

 nicknamed "butter birds." The species is likely to bring itself to the 

 attention of visitors in other ways as well, for it is of large size for a finch, 

 and the male possesses bright and contrasted coloration and a loud and 

 pleasing song. 



The black-headed grosbeak arrives on the west slope of the Yosemite 

 section during April. The species was common in Yosemite Valley on 

 April 29, 1916; and in early May, 1919, it was well established in the 

 western foothill country. East of the mountains its migrations are some- 

 what later. The first seen there in 1916 was observed on May 14. During 

 the summer season the birds are much in evidence and can scarcely be 

 missed by anyone who enters their domain. They quiet down in July, 

 and thenceforth are much less noticeable. Mr. Joseph Mailliard (1918, 

 p. 19) states that in 1917 none was seen in Yosemite Valley after Sep- 

 tember 20. This accords with our own findings in 1915 ; in that year the 

 birds departed from the Valley prior to September 24. 



These grosbeaks are abundant in both the Upper Sonoran and Transition 

 zones. At Pleasant Valley on May 23, 1915, 20 were recorded during a 

 4-hour census, and two days later 12 were noted in 2 hours. In Yosemite 

 Valley at the same season 8 to 12 birds were observed during each of 

 several 4-hour trips on the floor of the Valley. At Snelling the population 

 was smaller, and along the shores of Mono Lake the numbers were likewise 

 small, only 3 being seen in 3 hours at the latter locality on May 31, 1916. 

 In general, the preference of the species is for rather open foliaged, broad- 

 leaved trees, such as blue oaks, black oaks, and willows. The birds are 

 most likely to be found in scattered growths rather than in thick woods, 

 and generally they are not very far from water. 



The adult male black-headed grosbeak is a strikingly colored bird. 

 At first glance one gets an impression of black, white, and brown in highly 

 mixed pattern. Upon closer examination this coloring is seen to consist 

 of black on the head, back, wings, and tail, a large white patch on middle 

 of spread wing, and white thumb marks at the ends of the outer tail 

 feathers. There are also numerous scattered white spots elsewhere on the 

 wings. The rump, the collar around the back of the neck, and the under 

 surface of the body are colored brown, of a bright tone but not so red as 

 the breast of the robin. The female grosbeak is quite different. Dull 

 brown everywhere replaces the black, the amount of white is much smaller, 

 and the head and back are coarsely streaked. There is a conspicuous light 



