Белоплечий колючник Thamnophilus aethiops

Shy antshrike found in understory of lowland and foothill rainforest. Male is dark gray or black; he also has small white dots on the shoulder and a white line at the bend of the wing, but these features are not always evident in the field. Female is plain brown; on the western edge of the range, she also has a black face, throat, and tail. Usually first detected by voice: song is a soft series of evenly spaced, nasal caws.