National Geographic Magazine/Volume 31/Number 4/Friends of Our Forests/Worm-eating Warbler
The Warblers of North America
Range: Breeds mainly in the Carolinian Zone from southern Iowa, northern Illinois, eastern and western Pennsylvania, and the Hudson and Connecticut River valleys south to southern Missouri, Tennessee, Virginia, and mountains of South Carolina; winters from Chiapas to Panama, in Cuba and the Bahamas.
He who would make the acquaintance of the worm-eating warbler must seek it in its own chosen home, far from which it never strays. It is a bird of shaded hillside and dark thickets along watercourses. Though nimble in its movements and an active insect hunter, it is an unobtrusive little warbler, garbed in very modest colors, and is likely wholly, to escape the notice of the unobservant.
There seems to be an unusual degree of jealousy among the males, and a pair, the hunting and the hunted, are often seen pursuing a rapid, zigzag flight through trees and bushes. I imagine that in such cases the pursuing male, whose angry notes show how much in earnest he is, is asserting the right of domain over his own hunting grounds, and driving from his preserves an intruder.
Like several of our terrestrial warblers, the worm-eater has caught the trick of walking, perhaps borrowing it from his thrush neighbors, and he rarely or never hops. In his case the term “terrestrial” must be modified by the statement that to a certain extent he is a connecting link between the arboreal members of the family, as the black-throated green and Tennessee, which descend to the ground only casually, and such species as the Connecticut and the Swainson, which seek their food chiefly on the ground. Of the musical ability of the worm-eating warbler little is to be said save that his song is so very feeble that one must listen carefully to hear it at all, and that it much resembles that of our familiar “chippy” when heard a long distance off. This warbler nests on the ground, often on a hillside or in a shallow depression, and the pairs seem so much attached to their old home that they may confidently be looked for in the same place year after year.