It is a rather scruffy-looking bird, with a total length of approximately. The sexes are very similar in appearance, except that the female is slightly larger than the male. Juveniles appear quite similar to adults. The species has dark brown upperparts streaked with white, and whitish-buff throat, breast, underparts and rump. The tail is relatively long and broad, dark brown in color with a white-tip, and the legs are dark gray. The eyes and beak are yellow to orange, with a thin ring of featherless yellow skin around the eye. There is a prominent orange-rufous crest. Like other members of the subfamily Crotophaginae, the guira cuckoo gives off a strong, pungent odour.
Behaviour
The guira cuckoo is a bird of open habitats such as pastures and wetlands, and its range has expanded significantly due to deforestation. Within its distribution, it is commonly seen in suburban parks and gardens. Like the related squirrel cuckoo, the guira cuckoo is not a particularly adept flier, and usually flies only for short distances. It is often seen gliding or hopping from one perch to another while vocalizating loudly. The bird's call is unmistakable for being long and shrill, something between a long whistle and a wailing. Although it is primarily an arboreal bird, it is often seen foraging on the ground, sometimes alone but often in flocks of up to 18 individuals. It is sometimes seen with other birds whose behaviour is similar, such as the smooth-billed ani. Unlike many of the Old World cuckoos, the guira cuckoo does not practice brood parasitism or kleptoparasitism.
Feeding
The guira cuckoo is an opportunistic predator, gathering small prey items on the ground or searching for them among branches. It feeds on worms, insects and other arthropods, tadpoles and frogs, eggs, small birds and small mammals such as mice. It also has been observed feeding on lizards.
Nesting
The nest is built on a tree fork from the ground. The eggs are dark green and covered with a chalky layer. They are incubated either in individual or community nests; in the latter one can find up to 20 eggs. Under community nests there are many broken eggs. The competition between young being great, mortality is significant.
