TEXAS NIGHTHAWK. Chordeiles acutipennis texensis Lawrence

Field characters.—Same as those for Pacific Nighthawk (which see), but narrow white hand across long flight feathers (primaries) scarcely more than its own length from end of wing; in other words this white bar is well beyond middle of wing rather than close to midway. Voice: A mellow, long-continued, rolling trill.

Occurrence.—Common summer visitant to Lower Sonoran Zone. Seen in vicinity of Snelling and near Lagrange. Active during evening and morning twilight and during the night. Forages close over ground, rarely rising over 50 feet into the air. Rests during the day on ground in shade of bush or in open gravelly situation.

The Texas Nighthawk is a summer visitant to the warmer parts of the southwestern United States and in the Yosemite section it was observed only at our lowest stations, west of the foothills. On the evening of May 25, 1915, 3 were noted in flight over the river bottom near Snelling, the first at 7:15 P.M., well after sundown. The next evening 2 were abroad at about the same hour, 'hawking' over the alfalfa fields and doubtless in search of the night-flying insects to be found there.

When we established camp on a gravelly bench beside the Tuolumne River below Lagrange on the evening of May 5, 1919, it was evident at once that we had closely invaded the special domain of this nighthawk, for two pairs were coursing about actively at 6:30 P.M. (sun-time). The mellow trilling notes of the males were heard off and on throughout the succeeding night, so the birds must have been active during most of the hours of darkness. And on the following morning they were flying around now and then until about 8 o'clock.

It was the height of the nesting season and the birds were courting actively. A male, distinguished by the larger and whiter bands on his wings and the more conspicuously white chin patch, was pursuing a female. The male always followed, but at close range, rarely more than two lengths behind the female. Occasionally a second male joined in the pursuit, but evidently with only partial interest, for he frequently circled off by himself. Less often the two male birds pursued one another, weaving an irregular course up and down, in and out, but never rising much if any over 50 feet above the ground. The progress through the air was easy yet swift, a few strokes of the long wings sufficing to carry the birds through a long glide. Often as they passed close over the observer the barred pattern of the under surface was clearly visible, as was also the broad subterminal band of white on the lower side of the tail. While the males were on the wing their low crooning trills were heard almost continually, swelling and diminishing as the birds approached or departed. When they rested on the ground between flights they gave the same notes prolonged but also with longer intervals of quiet. One trill lasted 25 seconds and another fully a minute. These notes remind one of the quavering call of the Screech Owl save that they are longer continued, on one key, and uttered in almost the same cadence throughout.

Each individual nighthawk seemed to have a favorite resting place to which it returned regularly. This was on the gravel, at the side of, and partially shaded by, a lupine or other bush. The male bird of the pair mentioned was seen to return to the neighborhood of such a spot time and time again, and upon flushing him directly and thus ascertaining its exact location, the site was found to be marked by an accumulation of droppings of characteristic form—each a small spiralled mass composed chiefly of finely triturated insect remains.

Careful scrutiny of the ground within 100 feet of this male bird's 'roost' eventually led to the discovery of a 'nest' with two eggs which were being incubated by the female. The latter flushed when the observer was about 50 feet away, and then made off along the ground with a peculiar dragging flight, her wings fluttering and held downwards from the body, almost touching the ground. When she flew off, the male, who had been resting in his favorite spot, set up his crooning trill and continued it with varying loudness for a full minute, until the female alighted upon the gravel some distance away. When she again took wing he joined and followed close in her wake as she flew about. This was at 1:30 P.M., in the heat of the day.

The eggs lay 2 millimeters apart, and with their long axes at about 30° to each other, evidently just as the body of the female had fitted over them. They were situated on a little sandy area, in a tract generally covered with gravel. When not shielded by the female the eggs were fully exposed to the heat of the sun. The slender branches of a dead weed, 300 millimeters away to the southwest, formed the only semblance of a shelter. The bird could flush only to the northeast although she could easily see all about her for a hundred feet or more. The eggs were found (on May 6) to be about one-fourth incubated and one had a slight "stone bruise" which was covered on the inside by hardened albumen.

As is clearly seen in the illustration (pl. 45b) the coloration of the eggs is strikingly like that of many of the water-rounded pebbles in the vicinity. In all stages, egg, chick, and adult, the color scheme of the Texas Nighthawk is to the last degree protective in character—a feature of evident usefulness to a species which spends all of its life, except when foraging, on the open ground.