Речной колючник Thamnophilus cryptoleucus

Large black antshrike with a white back patch. Males have white wingbars, absent in females. An inhabitant of seasonally flooded forests, second growth, and river islands with dense understory composed of Cecropia and Heliconia vegetation. Forages in the understory and rarely accompanies mixed-species flocks. The song is an accelerating series of low descending notes.