DENDROICA NIGRESCENS (Townsend)
BLACK-THROATED GRAY WARBLER
Plate 35
HABITS
The black-throated gray warbler is neatly dressed in gray-black and white, with only a tiny spot of bright yellow in front of the eye. Its breeding range extends from southern British Columbia, Nevada, northern Utah, and northwestern Colorado southward to northern Lower California, southern Arizona, and southern New Mexico. It spends the winter in Mexico.
As a summer resident it is common and sometimes abundant in western Washington, even at lower elevations where, Samuel F. Rathbun tells me, it “prefers a locality somewhat open, with a second growth of young conifers; this may occur in the rather heavy forest, if such condition exists there, or along the edge of the timber; the species is partial to this character of growth.”
In southern Oregon, according to C. W. Bowles (1902), it seems to combine the habitat requirements of the eastern black-throated green and the prairie warbler. Like the former, it seeks tall trees, preferably conifers, well scattered and interspersed with bushes, since it nests in both. Like the prairie warbler, it chooses high dry places with dry ground underneath for its nest.
Farther south, the black-throated gray warbler seems to prefer growths of hardwood and underbrush for its summer haunts—oaks, scrub oak, pinyon, juniper, manzanita, and the like. Dr. Walter K. Fisher wrote to Dr. Chapman (1907) that, in California, “it lives in chaparral such as deer brush, wild lilac of various species, scrub oak, and sometimes, particularly in the humid coast districts, among evergreens. It is fond of the neighborhood of clearings where it works constantly and carefully among low growth.” Dr. Grinnell (1908) says that in the San Bernardino Mountains, “this warbler appeared to be be confined exclusively to the golden oak belt during the breeding season.” Referring to the Great Basin region, Dr. Linsdale (1938) writes: “The black-throated gray warbler was one of the few species adapted to occupy the piñon belt on the Toyabe Mountains. Not only did this bird tolerate conditions on dry slopes, but it was practically limited to them. The pairs were scattered far apart, but because this type of habitat takes up so much of the total area, this warbler must rank high among all the summer resident birds on the basis of numbers.”
This warbler is a common breeding bird in the mountains of southern Arizona. In the brushy foothills and canyons of the Huachucas, we found it between 4,000 and 7,000 feet in altitude, in the oak belt about halfway up the canyons, principally among the scrub oaks and manzanita bushes. In New Mexico, according to Mrs. Bailey (1928), it is found in summer at slightly higher levels, 5,500 to 8,000 feet, in the oak and pinyon pine country.
Nesting.—In Washington, the black-throated gray warbler seems to nest in fir trees exclusively, at heights ranging from 7 or 8 feet up to 50 feet above the ground. Rathbun has sent me the data for seven nests, all in firs, at heights ranging from 71⁄2 to 35 feet; they were all on horizontal branches and from 4 to 10 feet out from the trunk. He describes in his notes a typical nesting site as follows: “From a distance I saw a fir tree the character of which, from my experience, was favored by this warbler as a nesting place. It was of considerable size, one of a number scattered along the edge of the forest, and had considerable undergrowth beneath. After a very careful examination I located the nest near the extremity of one of the large lower limbs, at a distance from the trunk of 9 feet and at a height above the ground of 23 feet. The nest was placed at the side of the limb and was securely attached at a point where grew several small twig-like branches.” He says that this bird is very regular in its nesting date, the average date for fresh eggs is between June 3 and 8, and that the nest is always a neat one. He describes a typical nest as follows: “Plant fibers, dry grasses and a few very small weed-stalks were all neatly woven together to form the walls of the nest. The lining was a few feathers—two being those of the ruffed grouse, with others from sparrows, the quill of each being worked into the walls of the nest; next to this lining were soft and very fine plant fibers, with a few horsehairs.”