BARN SWALLOW. Hirundo erythrogaster erythrogaster Boddaert

Field characters.—Body size about that of a Linnet but tail and wings much longer and slenderer; tail deeply forked, with the outermost feathers very narrow toward tips (pl. 46e). Upper surface of body iridescent dark blue; forehead and under surface of body light reddish brown; chest with a dark band, not often complete. Voice: A series of twittering notes.

Occurrence.—Common summer visitant locally at low altitudes both east and west of Sierra Nevada. Recorded from Snelling and near Lagrange eastward to Bower Cave, 12 miles east of Coulterville; also, east of mountains, in neighborhood of Mono Lake. Chiefly near smooth flowing water; local distribution controlled largely by availability of suitable nesting sites such as low bridges. Usually in pairs, at most in small companies.

The general range of the Barn Swallow in the Yosemite region is practically the same as that of the Cliff Swallow, but as the nesting requirements of the two species are different, their local distribution is not the same. While the Cliff Swallow must have an expanse of wall, either of rock or board, and nests in colonies, the Barn Swallow prefers to live more apart and places its solitary nest on a beam beneath a bridge. Thus the Cliff Swallow is to be found in considerable numbers in a few localities, whereas small numbers of the Barn Swallow are found in many places through the lowland and foothill districts. By reason of its choice of nest site the Barn Swallow is often associated with the Black Phoebe.

The Barn Swallow differs conspicuously from all its fellows in the possession of a deeply forked tail (pl. 46e). This, in flight, is the most easily noted field character. When the bird is perched on a wire or twig the observer sees four points of feathers projecting backward from its body; these comprise the tips of the elongated and narrowed wings and the long outermost tail feathers. The six species of swallows found in the Yosemite section exhibit little difference in skill of flight, yet the Barn Swallow, with its attenuated tail, seems to us to be slightly more adept and certainly more graceful in its aerial coursing than its square-tailed relatives.

Like other hunting birds which feed exclusively on flying insects these swallows spend most of the daylight hours on the wing. At times they come to rest on a wire or other convenient perch where they are wont to spend some minutes in dressing and preening the long flight feathers of the wings. Depending as they do so completely on these organs for gaining their livelihood it is not to be wondered at that the swallows take exceedingly good care of their wings. In consequence of their care of their plumage and of the open nature of their forage area, the primary feathers do not show anywhere near so much wear as do the flight feathers of birds which inhabit shrubbery, grass or trees, whose feathers come in direct contact with these objects.

The Barn Swallow arrives in the Yosemite region during March and lingers until late summer or even early fall. Six individuals, including some young of the year already on the wing, were seen near Merced Falls on August 17, 1915. About 12 birds of this species were observed near Grant Lake, east of the Sierras, on September 14, 1915.

At Mono Mills on June 19, 1916, a nest of the Barn Swallow was found at the side of an old cellar which had once been used for the storage of potatoes. No bridge beams being available the birds had made use of the one site most nearly like that usually chosen. The nest contained five eggs in which incubation was well advanced.

In Bower Cave on July 18, 1920, a pair of these swallows was seen to enter a dark cavern at the bottom of the pit, skimming close over the water. One bird was carrying a fluffy white chicken feather which could be followed by the eye after the bird itself had become invisible in the gloom. Nest construction was probably under way even though, seasonally, the date was late. On July 20, 1920, near Dudley, 6 miles east of Coulterville, a nest containing two fresh eggs was discovered in a mining shaft 30 feet below the surface of the ground.

The Barn Swallow, like the Cliff Swallow, constructs a mud nest. But the nest of the former is open-topped, like a phoebe's, instead of retort-shaped, and has more straws and feathers incorporated into it.