The White-line Tanager has strong dymorphism, with the male being black with a small white line on the shoulder, and the female being entirely rufous. They normally forage in pairs, which helps in identifying them. Males can look very much like Scarlet-rumped Tanagers when the rump is not visible, but the bill is gray instead of blueish. The female is also similar to the Scarlet-rumped, however it has no marks and a black bill. They also approach fruit feeders but are more wary than Scarlet-rumped preferring to forage in the dense vegetation.