580 ANIMAL LIFE IN THE YO SEMITE 



Occurrence. — Common resident of Upper Sonoran Zone on west slope of Sierra 

 Nevada where recorded in nesting season from near Lagrange and at Pleasant Valley 

 eastward to Smith Creek, six miles east of Coulterville, and to El Portal. Strays to 

 higher altitudes in summer and fall months, as in Yosemite Valley, near Glacier Point, 

 and on slope north of Mirror Lake. Eecorded once east of mountains, at Williams 

 Butte, September 22, 1915. Forages chiefly in foliage of oaks, sometimes in tops of 

 the larger brush plants. In flocks of ten to twenty-five or so, except at nesting time 

 when in pairs. 



The California Bush-tit is a common inhabitant of the oak belt in the 

 western foothills of the Sierra Nevada. It is one of the smallest birds 

 found there, and is indeed one of the smallest birds in the Yosemite section, 

 not much larger than a hummingbird. The California Bush-tit 's coloration 

 is of the plainest sort, dull gray with no contrasted markings anywhere. 

 The top of its head is brownish, this being one of the features Avhich sep- 

 arate the present species from the Lead-colored Bush-tit found on the east 

 side of the Sierras; but this brown cap can be seen only at close range 

 and when looked for especially. Certain individual bush-tits have the iris 

 of the eye white though in the majority of the birds it is dark-colored. 

 This is a peculiarity which does not seem to be correlated with age, sex, 

 or season. 



The bush-tit is characteristically a flocking species and for the greater 

 part of the year the birds go in bands which number from ten to twenty- 

 five or more individuals. The separation into pairs for nesting occupies 

 the period from about late March through May. As soon as the young 

 are fledged the family goes about as a unit, soon joining one or more other 

 families to form the regulation flock. 



The flock formation of bush-tits is not so coherent as that of blackbirds 

 or sandpipers; each individual exercises a considerable measure of inde- 

 pendence, especially in changing its location. A foraging flock is usually 

 spread out through two or more trees and moves along slowly, the birds 

 stringing along one after another, all going in the same direction from 

 tree to tree, but no two moving at exactly the same instant. Those in 

 the rear fly ahead and in turn are passed by their companions. While 

 engaged in ordinary foraging the members of a flock keep up a series of 

 faint notes which doubtless help to keep the band together. At times an 

 individual wiJl become absorbed in foraging in one particular place and 

 be left behind by his companions. The belated one then utters a series 

 of notes quite insistent in tone, and as soon as he gets a response indicating 

 the new location of the flock he hurries on in direct course to join the 

 others once more. 



In general behavior bush-tits remind one of chickadees. Individual 

 birds when hunting food will assume any position, even that of hanging 

 inverted from some small branch or leaf. Their foraging is done very 

 largely in the foliage of the live oaks, the leaves being scrutinized from 



