It has a total length of approximately 18 cm (7 in).
It is overall ashy-brown with contrasting black lores and rufous wings.
The taxon fringillarius has more black in the face and is overall more rufescent (less ashy).

It is social and commonly seen in small groups.
Unlike the "true" cowbirds in the genus Molothrus, this species is not a brood parasite.
In contrast, the screaming cowbird is a brood parasite of the grayish baywing, and while adult screaming cowbirds are overall blackish, juvenile screaming cowbirds closely resemble grayish baywings.
It has a total length of approximately 18 cm (7 in). It is overall ashy-brown with contrasting black lores and rufous wings. The taxon fringillarius has more black in the face and is overall more rufescent (less ashy).
It is social and commonly seen in small groups. Unlike the "true" cowbirds in the genus Molothrus, this species is not a brood parasite. In contrast, the screaming cowbird is a brood parasite of the grayish baywing, and while adult screaming cowbirds are overall blackish, juvenile screaming cowbirds closely resemble grayish baywings.
Grayish baywing