Costa rican warbler Basileuterus melanotis

Small understory warbler, dull buffy-brown overall. Bold black stripes on head, including cheek patch. Sexes alike. Recalls Worm-eating Warbler but plumper with longer tail; face pattern different. Found in pairs or small flocks moving through the forest understory. Often with a mixed-species flock. Energetic twittering song is a good clue that there’s a flock nearby.