guira, (Guira guira), bird of eastern tropical South America in the cuckoo family, Cuculidae. It is 40 cm (16 inches) long, with gray-brown streaked body, short frowsy crest, and a thinner bill than that of its close relatives, the anis. Guiras live in small flocks in grasslands and feed on grasshoppers and other insects. Guiras, like anis, give off a strong, pungent odour.