The lack of yellow in the plumage of the Black-throated Gray Warbler (except for the lores) distinguishes it from all warblers except the Blackpoll (alternate male) and Black-and-white Warblers. Both those species have different face patterns and the Black-and-white Warbler behaves quite differently preferring to forage on the trunks and main branches of trees nuthatchlike rather than in the leaves and smaller twigs.
Length and wingspan from: Robbins, C.S., Bruun, B., Zim, H.S., (1966). Birds of North America. New York: Western Publishing Company, Inc.