The grey-bellied cuckoo is a smallish cuckoo at 23 cm. Adults are mainly grey with a white lower belly and undertail. The wings have a white patch on them. Some female are of the hepatic form, which is dark-barred reddish brown above with an unbarred tail, and has strongly dark-barred whitish underparts. The juvenile is a duller greyer version of the female.The grey-bellied cuckoo takes a variety of insects and caterpillars. It is a brood parasite, and lays its single egg in the nests of warblers.