The Wilson's Warbler is a small bird of the warbler family. Males of the species can be recognized by the black cap they sport. Females have a lighter crown patch or none at all. Both sexes have more... similar body plumage: yellow underparts and olive-green upperparts. The Wilson's Warbler is named for the ornithologist who discovered the species for science in 1811: Alexander Wilson. This is our totally cute Birdorable Wilson's Warbler!