BLACK PHOEBE. Sayornis nigricans (Swainson)

Field characters.—But slightly longer than English Sparrow (length 6-1/2 inches); build slender; head with a low crest. Plumage solidly black-appearing except for white of belly. Perches on boulders, posts, telephone wires, and buildings; frequently turns head from side to side, and at intervals moves tail up and down. Voice: Usually a one-syllabled call, shrill and rather plaintive, pser; also, as a 'song,' a persistent repetition of two pairs of similar notes, with alternate rising and falling inflection.

Occurrence.—Resident in Upper and Lower Sonoran zones, barely entering the lower part of the Transition, as at Smith Creek (Dudley's ranch); an occasional individual reaches the floor of Yosemite Valley. Lives along streams and about unpainted buildings.

The black garb and typical flycatcher habits of the Black Phoebe combine to make it one of the easiest of birds to identify; moreover, its preference for open situations along streams and about buildings brings it to the attention of even casual observers within the stretch of country which it inhabits.

Like most flycatchers this species is solitary and the individual birds, even of a mated pair, are usually widely separated. The Black Phoebes are most frequently seen along rock-bordered streams, like the lower Merced River. From the windows of the train as it traverses the Merced Cañon, birds of this species may often be observed perched low on boulders 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 exceptionally 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 thereafter the species was seen daily until September 25.

Whatever its surroundings the Black Phoebe seems to prefer a conspicuous 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 constantly, 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 Cave 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.