FLYCATCHEES 36;^ 



near the water or flying rather slowly out over the surface of the river. 

 In the river bottom at Snelling, in January and again in June, one of 

 our party noted six during a three-hour census. The birds were excep- 

 tionally numerous there, for seldom does an observer meet with more 

 than one or two in a morning's walk. 



The Black Phoebe does not normally occur higher than the limits of 

 the Upper Sonoran Zone ; but an occasional individual reaches the floor 

 of Yosemite Valley. On October 23 and November 6, 1915, lone birds 

 were seen on Sentinel Meadow, perching on telephone wires or on bare 

 tips of willows in the swales. On May 21 and 22, 1919, one held forth 

 from a perch over the river near Stoneman bridge. In 1920 (C. W. 

 Michael, MS) the first one in the Valley was noted on July 29 and there- 

 after the species was seen daily until September 25. 



Whatever its surroundings the Black Phoebe seems to prefer a con- 

 spicuous location for its forage perch. Often it posts itself on the tip of 

 a dead twig at the edge of a stream, or on the corner of a building, whence 

 it sallies forth for passing insects, making but a short circuit before 

 returning. When on watch its head moves from side to side almost con- 

 stantly, and its tail is raised and lowered at short intervals. The short 

 plaintive one-syllabled call note, pser, is uttered simultaneously with an 

 emphatic movement of the tail. This single call is at times replaced by 

 a series of four syllables, two with rising and two with falling inflection. 

 A bird giving this song near Bower Gave on May 13, 1919, was seen to 

 spread its tail synchronously with each pair of notes so that the narrow 

 white margin of the outer tail feathers showed momentarily. 



Black Phoebes are not distributed locally with the regularity observed 

 in shrubbery-inhabiting birds such as Wren-tits or Brown Towhees. The 

 peculiar nesting requirements of the phoebes probably account for this 

 lack of uniformity in their distribution. They must have sheltered faces 

 of rocks or wooden walls against which to place their nests, and these 

 sites must be within carrying distance of some source of the mud used 

 in nest construction. Such sites are widely and irregularly scattered. 

 The building of bridges over creeks and the maintenance of stock barns 

 with watering troughs near by have probably increased the population 

 of these birds in the country as a whole. 



At Dudley's ranch on the Coulterville Road a nest of this species was 

 seen on June 5, 1915. On that date it contained six young not more than 

 a day or so old. The nest was a cup-shaped affair, composed of mud pellets 

 with a few fine grass stems intermixed. It was placed under the gable 

 of a shed, about fifteen feet above the ground. 



