Evening Grosbeaks are medium-large songbirds with very thick, seed-cracking bills. They are highly sexually dimorphic. The males have blackish heads, bright yellow undersides and backs, black wings with large, white wing-patches, and black tails. They also have yellow brows. Their bills become greenish in spring and summer. Females are brownish-gray with dark heads. They have black wings with white patches, but less white on their wings than the males. They also have yellow underwings. Juveniles look similar to females.