Quite large warbler, olive-green above and yellow below. Distinctive features include longish, daggerlike bill, long primary projection in the wings, and square tail. Told from similar Melodious Warbler by usually conspicuous pale wing panel and gray (not brown) legs. Usually difficult to see when singing except during song flights, when long wings are apparent. Found in tall forest with oaks and birch, mixed forest, gardens, and parks. Song is fast, loud, and melodious with lots of mimicry.