Generally shy and elusive, the yellow-billed cuckoo can be easily overlooked. Its calls are usually loud and often provide the best evidence to the presence of the bird. It favors eating caterpillars and seems to respond well to outbreaks of tent caterpillars.

The yellow-billed cuckoo has a slender body, a long tail, and rounded wings. Adults have grayish brown upperparts with whitish underparts. The crown can be noticeably grayer than the rest of the upperparts on some individuals. The rounded wings have reddish primaries. The long tail is graduated with brown central rectrices tipped in black; the remainder are black and broadly tipped with white. It has a yellow orbital ring. The bill is curved with a black culmen extending over