コシアカアリサザイ Euchrepomis callinota

Colorful for an antwren, and therefore might be difficult to place into the correct family at first. Small. The distinctive rufous rump can be hard to see, so note black cap, gray head, olive back, yellow wingbars, and yellow belly. Bill is quite long and narrow. Female is similar to male but slightly duller. Typically found in pairs. Follows mixed-species flocks through the forest, usually fairly high in the canopy.