Blue jays are relatively large songbirds (about the size of a robin) with blue upperparts and whitish underparts. A blue crest on the head can be raised or lowered depending on the bird’s mood. The back is rather lavender, and the wings and tail are sky blue with black bars and white highlights. The strong bill and feet are black; the face is white and is nearly surrounded by a black collar. The voice varies from soft murmurs to loud screams to clear, chime-like whistles.