Bachman's Warbler - Description

Description

Bachman’s Warbler is a sexually dimorphic species and the adults have two distinct plumages, one for the spring and one for the fall. In the spring, adult males have a yellow forehead, supraloral, and supercilium. The area below the bird’s eye is yellow, while the lores are a dusky olive. The bird’s forecrown is black with gray at the edges, while the rear crown and nape are olive-gray. The rest of the bird’s upperparts are an olive green, with the rump being the brightest. The chin and upper throat are yellow, while the center throat and upper chest are black. The belly is yellow, and the undertail coverts are white. Males in their first spring are nearly identical to the adult male, but have less black on their crown and chest.

During the spring, adult females are a light yellow in their forehead and supraloral, blending into the gray crown and nape. Its lores are a gray-olive and it has a white eye ring. The rest of the female’s upperparts are an olive-green, which like the male is brightest on the rump. The chin and throat are also a light yellow, while the sides of the neck and the upper breast are gray. Older females have a few black upper breast feathers. The rest of the breast and the belly is light yellow, blending into white on the undertail coverts. The flanks are also washed with gray. First spring females resemble the adult female, but appear to be more worn.

Bachman’s Warbler molts over the summer into its fall plumage. For adult males, the fall plumage is nearly identical to the spring, with the only difference being that the forecrown changes from black to gray. First year males also resemble their spring plumage, but have an olive forecrown and duller yellow underparts. Adult females possess the same plumage, though it looks fresher in the fall, while first year females have an olive-yellow forehead and a dull eyering.

Hatchlings obtain their first plumage in May and undergo their first molt in June. Juvenile Bachman’s Warblers have a dusky brown head and upperparts and are a paler brown below, which transitions to dull white on the lower body and undertail.

This warbler is 4.25 inches (0.108 m) in length. Its is relatively small for a warbler and has a short tail. It is unique amongst warblers for its thin and decurved bill. The bill of Bachman’s Warbler is blackish brown in adults and brown in the young. The legs are a grayish-brown, while the eyes are dark brown.

Bachman’s Warbler’s song is composed of a rapid series six to twenty-five buzz notes, sometimes ending in a sharp, slurred note zip. Five to ten buzz notes were delivered in a second. This song was noticeably monotone, which differentiated it from species such as the Northern Parula. Multiple call notes have been recorded, ranging from a soft tsip to a low, hissing zee-e-eep.