Sp. Char. Forehead, line over and around the eye, and under parts generally, bright yellow. Upper part olive-green; a square patch on the crown lustrous-black. Sides of body and cheeks tinged with olive. No white on wings or tail. Female similar, the black of the crown replaced by olive-green. Length, 4.75; wing, 2.25; tail, 2.30.
Hab. Eastern portions of United States, west to the Snake and Humboldt Rivers; north to Alaska, south through Eastern Mexico and Guatemala to Costa Rica; Chiriqui (Salvin).
Habits. Wilson’s Black-Cap is found throughout the United States from ocean to ocean, and as far to the north as Alaska and the Arctic shores, where, however, it is not common. Mr. Dall shot a specimen, May 30, on the Yukon River, where it was breeding. Mr. Bischoff obtained others with nests and eggs at Sitka, and afterwards found it more abundant at Kodiak. On the Pacific coast Dr. Suckley found it very abundant in the neighborhood of Fort Steilacoom, where it frequented thickets and small scrub-oak groves, in its habits resembling the Helminthophaga celata, flitting about among the dense foliage of bushes and low trees in a busy, restless manner. He describes its cry as a short chit-chat call. In California, Dr. Cooper notes their first arrival early in May, and states that they migrate along the coast, up at least to the Straits of Fuca. At Santa Cruz he noted their arrival, in 1866, about the 20th of April. They were then gathering materials for a nest, the male bird singing merrily during his employment. As they have been observed in Oregon as early as this, it has been conjectured that some may remain all winter among the dense shrubbery of the forests.
This bird winters in large numbers in Central America, where it is apparently very generally distributed. Mr. Salvin found it very common at Duenas. It was taken at Totontepec, among the mountains of Oaxaca, Mexico, by Mr. Boucard.
Mr. Ridgway found it very common during the summer and autumn months among the willows of the fertile river valleys, and among the rank shrubbery bordering upon the streams of the cañons of the higher interior range of mountains. It was found in similar situations with the Dendroica æstiva, but it was much more numerous. During September it was most abundant among the thickets and copses of the East Humboldt Mountains, and in Ruby Valley, at all altitudes, frequenting the bushes along the streams, from their sources in the snow to the valleys.
Wilson first met with and described this species from specimens obtained in Delaware and New Jersey. He regarded it as an inhabitant of the swamps of the Southern States, and characterized its song as “a sharp, squeaking note, in no wise musical.” It is said by him to leave the Southern States in October.
Audubon states that it is never found in the Southern States in the summer months, but passes rapidly through them on its way to the northern districts, where it breeds, reaching Labrador early in June and returning by the middle of August. He describes it as having all the habits of a true Flycatcher, feeding on small insects, which it catches on the wing, snapping its bill with a sharp clicking sound. It frequents the borders of lakes and streams fringed with low bushes.
Mr. Nuttall observed this species in Oregon, where it arrived early in May. He calls it a “little cheerful songster, the very counterpart of our brilliant and cheerful Yellow-Bird.” Their song he describes as like ’tsh-’tsh-’tsh-tshea. Their call is brief, and not so loud. It appeared familiar and unsuspicious, kept in bushes busily collecting its insect fare, and only varied its employment by an occasional and earnest warble. By the 12th of May some were already feeding their full-fledged young. Yet on the 16th of the same month he found a nest containing four eggs with incubation only just commenced. This nest was in a branch of a small service-bush, laid very adroitly, as to concealment, upon a mass of Usnea. It was built chiefly of hypnum mosses, with a thick lining of dry, wiry, slender grasses. The female, when approached, slipped off the nest, and ran along the ground like a mouse. The eggs were very similar to those of Dendroica æstiva, with spots of a pale olive-brown, confluent at the greater end.
A nest found by Audubon in Labrador was placed on the extremity of a small horizontal branch, among the thick foliage of a dwarf fir, a few feet from the ground and in the very centre of a thicket. It was made of bits of dry mosses and delicate pine twigs, agglutinated together and to the branches and leaves around it, from which it was suspended. It was lined with fine vegetable fibres. The diameter of the nest was three and a half and the
depth one and a half inches. He describes the eggs, which were four, as white; spotted with reddish and brown dots, the markings being principally around the larger end, forming a circle, leaving the extremity plain.