Food.—The food of the yellow-throated warbler has apparently not been well investigated. Little appears in the literature, an illustration of the need to learn more of the diet of small, woodland birds. Records of the examination of seven stomachs reveal that insects compose most of its diet, for according to Howell (1932) “beetles, moths and their larvae, flies, bugs, grasshoppers, grouse locusts, crickets, scale insects, and spiders” are included in the food. Witmer Stone (1937) in writing of the first observance of this warbler at Cape May Point, N. J., on July 13, 1920, states that he saw it take “a green caterpillar about an inch in length.” D. J. Nicholson has noted (1929) that while watching one of these birds in Volusia County, Fla., he saw it eat at least ten “worms” in a few minutes as it searched the trees near where he sat.
I have often watched these warblers feeding in my yard and have seen them take small, active caterpillars on numerous occasions. There seems little doubt that scale insects are often taken, as the yellow-throated warbler, creeping about the limbs of trees as it does, undoubtedly finds many of these tiny, but destructive pests. There can be little question as to its benefit to agriculture.
Behavior.—There is much that is reminiscent of the brown creeper in the habits of the yellow-throated warbler. Its actions are deliberate and methodical, with none, or very little, of the nervous energy so characteristic of many species of Dendroica. As a result it is easier to watch than many other warblers, and its technique of hunting frequently brings it close to the observer. Pearson and the Brimleys (1942) state that it confines its creeping search to the limbs of trees, omitting the trunks altogether. However I have seen this warbler in my yard, feeding on the trunks of both pines and oaks. In this posture, it acts almost exactly like the black-and-white warbler (Mniotilta varia) and the brown creeper (Certhia familiaris). D. J. Nicholson of Orlando, Fla. (1929), mentions that he has seen them feeding on the “mossy trunks” of trees.
Milton P. Skinner (1928) writes:
Yellow-throated warblers are gentle and friendly, but are not really socially inclined, either toward other members of their own kind or toward other species. * * * In the trees, their movements are quick, nervous and active, and they are very neat and trim in appearance for they spend much time in preening * * * As usual with warblers, these little birds are skillful insect catchers, and eat house flies, mosquitoes, ants, crickets, beetles and many other varieties of the smaller insects. Once I saw one on an artificial feeding station eating bread crumbs.
These warblers seem even fonder of bathing than most other warblers. They go regularly and often to their baths, and after bathing they spend several minutes carefully preening their feathers.
Voice.—The song of the yellow-throated warbler is one of its distinctive characteristics. Completely unlike the thready, insect-like notes of many of its family, it is difficult to describe verbally, and interpretations of it must necessarily vary according to impressions made on human ears. That it is loud, with a definitely ringing character, is agreed upon by all, and in this respect resembles the beautiful song of the prothonotary warbler (Protonotaria citrea) another dweller of the cypress lagoons.
R. T. Peterson (1939) says that the song is “slightly suggestive” of those of the indigo bunting (Passerina cyanea) and the Louisiana water-thrush (Seiurus motacilla), although I had not noticed this resemblance, and describes the notes as “starting with several clear, slurred notes and dropping slightly down the scale.” This is true; the preliminary or “clear” notes vary in number from five to eight, and are run together at the end. F. M. Weston (MS.) says that there are “several distinct repetitions of a single note, ending weakly in an anticlimax trill,” also a satisfactory description. Rendered into words (always inaccurate and often misleading) it has been written as ching-ching-ching-chicker-churwee. F. M. Chapman (1907) remarks that he was familiar with the song for some years before being impressed with its resemblance to that of S. motacilla, and follows with the statement that it is not so much the form of the notes themselves “as their wild, ringing, carrying quality which recalls the song of the water-thrush,” in which quality a resemblance is readily understandable, and further says that the song has been compared to that of the indigo bunting “not without reason.” Howell (1932) simply characterizes it as “loud and attractive,” and also compares it with that of the indigo bunting and the water-thrush.
Aretas A. Saunders (MS.) writes: “The song is bright, musical and lively, beginning with high-pitched two-note phrases, sounding something like cheeka-cheeka-cincha-cincha, and then dropping down in pitch in a series of rapid notes. It is fairly loud, with a clear ringing quality.” This is much the best description I have seen of this highly individual song.