Audubon's warbler (Setophaga auduboni) is a small bird of the family Parulidae. At one time considered a distinct species, discovery of a hybrid zone between it and the myrtle warbler in 1973 has led to it being classified as a subspecies of the yellow-rumped warbler.

Black-fronted warbler, Setophaga auduboni nigrifrons is a subspecies found in Chihuahua to Durango, Mexico.

Description

thumb|right|Female Audubon's warbler in summer plumage|300px

In the spring and summer, the adult male has a dark back with a bright yellow throat, rump, and flank patch, and black head and back. The adult female's throat and shoulders contain less yellow than the males and is further distinguished by the brown in its back and its white wing bars compared to the white wing panels of the males. The juvenile male is similarly colored but with more black in its tail and can be distinguished by its incomplete wing panel. The juvenile female is much browner than the adult female and has whitish shoulders and some yellow in the throat.

In the fall and winter, the adult male has a grey and black back with black lores and black streaks in the breast. However, there is significant overlap with the adult female so the identification of the adult male can be conclusive only if there is extensive black across the back and breast. The adult female and juvenile male are virtually indistinguishable and have lighter breast streaking and are browner than the adult male. The juvenile female is very dull and has a slightly-tinted yellow throat but there is considerable overlap between the juvenile female and adult female. The two can only be definitely distinguished in cases where the juvenile throat is white or the juvenile displays two feather ages in its greater converts.

This form is distinguished from the myrtle warbler by its lack of a whitish eyestripe, its yellow throat, and concolorous cheek patch.

The song is a simple trill, and they make a hard check call. Both males and females measure between long, with a wingspan of . Both sexes typically weigh between .

Behaviour and ecology

Audubon's warbler tends to be rather active, typically spotted while catching insects during the warmer months in the year.

  • New World Warblers by Curson, Quinn and Beadle,
  • Cornell University All About Birds guide to yellow-rumped warbler species distinctions