Anis (Smooth-billed and the very similar Groove-billed) are bizarre, coal-black cuckoos with long floppy tails and unique, very deep and broad-sided bills. They occur in tropical lowlands and foothills, in a variety of open and semiopen habitats. In most places, only one species occurs, but the two occur together locally, as on Cozumel Island. Smooth-billed is slightly larger, with overall smooth sides to the bill. The typical calls of the two species are different; Smooth-billed has a hawklike, whistled scream.