Nesting.—Dr. Bachman did not discover the breeding grounds of this warbler, and it was more than 60 years before the first nests and eggs became known to science; Widmann (1897) found the bird breeding in the St. Francis River country of Missouri and Arkansas on May 13, 1897. The nesting area extended “over two acres of blackberry brambles among a medley of half-decayed and lately-felled tree-tops, lying in pools of water, everything dripping wet with dew in the forenoon, and steaming under a broiling sun in the afternoon.” The first nest, which he describes as being 2 feet from the ground, “was made of leaves and grass blades, lined with a peculiar black rootlet; it was tied very slightly to a vertical blackberry vine of fresh growth and rested lightly on another, which crossed the former at a nearly right angle. From above it was entirely hidden by branchlets of latest growth, and the hand could not have been inserted without at first cutting several vines, overlying it in different directions.”
Ridgway (1897) describes this nest as, “a somewhat compressed compact mass composed externally of dried weed- and grass-stalks and dead leaves, many of the latter partially skeletonized; internally composed of rather fine weed- and grass-stalks, lined with black fibres, apparently dead threads of the black pendant lichens (Ramalina, species?) which hang in beard-like tufts from button-bushes (Cephalanthus) and other shrubs growing in wetter portions of the western bottom-lands. The height of the nest is about 31⁄2 inches; its greatest breadth is about 4 inches, its width in the opposite direction being about 3 inches. The cavity is about 11⁄2 inches deep and 11⁄2 × 2 inches wide.”
In 1906, Wayne (1907) found six nests of Bachman’s warbler near Charleston, S. C., from two of which the young had flown. "The swamp in which this warbler breeds is heavily timbered and subjected to overflow from rains and reservoirs. The trees are chiefly of a deciduous character, such as the cypress, black gum, sweet gum, tupelo, hickory, dogwood, and red oak. In the higher parts of the swamp short-leaf pines, water oaks, live oaks, and magnolias abound. The undergrowth is chiefly cane, aquatic bushes, and swamp palmetto, while patches of blackberry brambles and thorny vines are met with at almost every step.” The first two nests, found on April 17, are described as follows:
The first nest was placed upon a dead palmetto leaf, being supported by a small aquatic bush, and was completely hidden by a living palmetto leaf which overhung the nest, like an umbrella. It was in a dense swamp, two feet above the ground, and contained four pure white eggs, almost ready to be hatched.
The second nest, which was within one hundred yards of the first one, was built in a bunch of canes (Arundinaria tecta), and supported by a palmetto leaf. This nest was three feet above the ground, in a comparatively dry situation, and contained four pure white eggs in an advanced stage of incubation. * * *
The two nests are similar, being constructed of fine grass, cane leaves, and other leaves, the latter skeletonized. The second nest, taken April 17, is 61⁄2 inches high, 6 inches wide, 2 inches wide at rim, and 2 inches deep. It is composed almost entirely of dead cane leaves, a little Spanish moss (Tillandsia usneoides), and a few skeletonized leaves. * * *
The female is a very close sitter; indeed so close that I found it necessary to touch her before she would leave the nest. This habit was the same in both females.
The other nests were in low bushes, vines, or canes.
During that same year Embody (1907) discovered Bachman’s warbler breeding in Logan County, Ky., and later Holt (1920) found it nesting in Autauga County, Ala. The localities in which these birds were breeding and the locations of the nests were not very different from those described above by Wayne.
Eggs.—The egg of Bachman’s warbler is ovate and pure white, and usually glossy. The only spotted egg on record is one of a set described by Holt (1920) as follows: “The nest contained four eggs, three of them pure, glossy white, the other with a dozen minute dots of light brown, mostly about the large end; all were tinted faint salmon pink by the yolks.” Three to five eggs constitute a set; three seem the usual number, with four a close second, while five are unusual.