WHITE-CROWNED SPAEEOWS 447 



White-crowned Sparrows occur somewhere in the Yosemite region at 

 all times of the year, but the same individuals are not continuously in 

 residence at any one place nor is the species to be found in any one locality 

 at all seasons. As explained in footnote 27 there are two subspecies rep- 

 resented in the region. One of these, the Hudsonian White-croAvned Spar- 

 row, is the summer representative at the higher altitudes, while the other, 

 the Intermediate White-crowned Sparrow, or Gambel Sparrow, is to be 

 found in winter at the lower elevations to the west, and elsewhere in 

 migration. The change, while involving considerable time during the 

 spring and fall seasons of migration, is eventually complete, for none of the 

 former race has been found in the region in winter nor do any of the latter 

 remain there to nest in summer. 



The earliest definite records of the arrival of the Hudsonian White- 

 crown in the Yosemite region are for May 10 (1916) near Williams Butte 

 and for May 8 (1917) at Smith Creek, east of Coulterville. Migration 

 was still in progress on May 22 (1919), as a male bird in Yosemite Valley 

 on that date tarried only a short time before moving on. The birds often 

 establish themselves in the leafless willow thickets which border the streams 

 in the boreal meadows before human invasion of those heights is easy. 

 Hence, the first travelers of the season are apt to find the White-crowns 

 already busy with nesting duties. Some individuals continue in their 

 summer haunts until the end of September, several having been noted by 

 us at Tuolumne Meadows on September 29, 1915, but none anywhere later 

 than that date. 



Our highest record for the Hudsonian White-crowned Sparrow was 

 close to 11,000 feet altitude, in a patch of stunted willows in a draw between 

 Mount Gibbs and Mount Dana, July 29, 1915. 



The occurrence of the Intermediate Sparrow in the lower zones is 

 practically complementary to that of its congener at the higher altitudes. 

 Our earliest fall record for gambeli was made near Williams Butte on 

 September 17, 1915. In Yosemite Valley the earliest date of its occurrence 

 is September 18, 1917 (Mailliard, 1918, p. 18). Numbers were seen in the 

 Valley on September 24, 1915. After mid-September the birds are to be 

 met with commonly in the brush lands below 4500 feet. We think it likely 



British Columbia northward, and which is distinguished by having grayish white (instead 

 of black) between bill and eye (pi. 8c) is a winter visitant in the lower zones (Sonoran) 

 from Snelling and Lagrange eastward to El Portal; it also passes as a migrant, in 

 fall and spring, along the east side of the Sierras in vicinity of Mono Lake, west to 

 Walker Lake and Warren Fork of Leevining Creek, and is common in Yosemite Valley 

 in the fall. It arrives in mid-September (September 17, 1915, near Williams Butte) and 

 departs in late spring, remaining as late as May 6 (1919, at Lagrange). Frequents 

 brush and small trees. Loosely flocking. 



White-crowned sparrows may often be approached closely enough in the field for 

 the observer to see whether the small area between bill and eye is black (leucophriis) or 

 gray {gamheli). The two subspecies will not often be found on common ground, and 

 any particular bird not closely seen may usually be guessed as to name by giving con- 

 sideration to date and place of occurrence. 



