Nuttall describes their notes and their habits as resembling the common Parus atricapillus, and remarks that they are constantly uttering a complaining call, sounding like tshe-dē-dē.
Until quite recently, nothing has been positively known in regard to its nesting. Audubon has described its nest as made of dry mosses and the fallen bloom of the hickory and the chestnut, and as built in bushes several feet from the ground. He describes the eggs as cream-colored, marked about the larger end with reddish-brown. These descriptions have not been confirmed, and all our information has led us to look for its nest on the ground.
Mr. Trippe states that it is found, but is not at all common, near Orange, N. Y., where it arrives about the middle of May. It has, at that time, a rapid, chattering note, and it always, he says, keeps near the ground, and, besides its chattering song, has in June a series of odd notes, much like those of the White-breasted Nuthatch, but more varied and musical, yet hardly entitled to be called a song.
Mr. T. H. Jackson of Westchester, Penn., in the American Naturalist for December, 1869, mentions finding the nest and eggs of this bird. We give his account in his own words: “On the 6th of June, 1869, I found a nest of this species containing five eggs. It was placed in a hollow on the ground, much like the nests of the Oven-Bird (Seiurus aurocapillus), and was hidden from sight by the dry leaves that lay thickly around. The nest was composed externally of dead leaves, mostly those of the beech, while the interior was prettily lined with the fine, thread-like stalks of the hair-moss, (Polytrichium). Altogether it was a very neat structure, and looked to me as though the owner was habitually a ground nester. The eggs most nearly resemble those of the White-bellied Nuthatch (Sitta carolinensis), though the markings are fewer and less distinct. So close did the female sit that I captured her without difficulty by placing my hat over the nest.”
The same observing ornithologist informs me that this Warbler arrives in Pennsylvania early in May, and makes the most solitary part of the woods its home, outside of which it is rarely seen. True to its name, it is ever busy hunting out and devouring the worms that lurk among the forest foliage, pursuing its avocation in silence, with the exception of a faint note uttered occasionally. This species is not as shy as many of our Warblers that frequent the woods. Towards the latter part of May they commence constructing their nests. Mr. Jackson adds that the nest above referred to was found on a thickly wooded hillside, a few yards above a running stream. So neatly was it embedded in the ground and covered with dry leaves, that discovery would have been impossible had not the female betrayed its position. Both birds exhibited the greatest alarm at his presence, but on his retiring to a short distance the female returned to the nest, where she was easily captured. The base and periphery of the nest were composed of dry beech-leaves, while the inner lining was made of fine hair-mosses (Polytrichium).
In the latter part of June, 1871, Mr. Jackson found another nest of this species, containing five young birds about half grown. He was seated on a log, resting after a hard tramp, when a Worm-eating Warbler alighted near him, having a large green worm in its beak. After at first manifesting much uneasiness, and scolding as well as she could, she suddenly became silent and flew to the ground. On his going to the spot both parents flew from the nest. It was in all respects, in regard to materials, manner of construction, and situation, the exact counterpart of the other. Both were placed on steep, wooded hillsides, facing the east.
Two of the eggs of this Warbler thus identified by Mr. Jackson, and kindly loaned to me by him, are of a somewhat rounded-oval shape, less obtuse at one end. They have a clear, crystal-white ground, and are spotted with minute dottings of a bright red-brown. These are much more numerous in one than in the other, and in both are confluent at the larger end, where they are beautifully intermingled with cloudings of lilac-brown. These eggs measure, the one .78 by .60 of an inch; the other, .70 by .56 of an inch.
Another nest of this species, found by Mr. Joseph H. Batty of New York, on the side of a hill near Montclair, N. J., was also built on the ground, in a part of the woods where there was no underbrush, and was placed in a slight hollow, with dry oak-leaves collected around it, and partly covering it. The nest was made of dry leaves, and lined with grasses and fine roots. It contained four eggs, alike in their marking, and corresponding exactly with those obtained by Mr. Jackson. Mr. Batty nearly stepped on the bird without her leaving the nest.
Dr. Coues found the Worm-eating Warbler a rather uncommon summer resident near Washington, breeding there but sparingly. It arrives there during the first week in May, and remains until the third week in September. He describes it as slow and sedate in its movements.