Common and widespread breeder and migrant in deciduous and mixed forest. Scarce in winter. Distinctive behavior: creeps on or under branches, sometimes upside down, like a black-and-white mouse. Nests on ground. On migration joins feeding flocks that will often include several BWWA. ID: A medium-sized warbler with short tail, heavy in the belly, and long, downcurved bill, and pointed head — a distinctive profile. Large feet for grasping branches. From below, black undertail coverts are a giveaway. Despite large variation in plumages, the bold black-and-white striped head pattern and coloring make it an easy warbler to ID. Ad ♂ br: solid black cheeks, throat, and flank streaking. Throat and ear coverts paler toward fall. Ad ♀/1st-yr ♂: paler than ad ♂ with white ear coverts and throat. Diffuse streaking on variably buff flanks and undertail coverts. 1st-w ♀: paler and more buff. 1st-yr birds have brown greater primary coverts.