Bird Species Spotlight: Guira Cuckoo

I saw my first Guira Cuckoo on the ground in the grasslands of Brazil in 2018. These cuckoos are frequent visitors to drier habitats, such as second-growth scrub, scrub savannahs and woodlands, pampas, pastures, fields and coastal dunes. They are very social birds and live in groups of 6 to 8 individuals, although as many as 20 birds in one flock have been recorded. They are very noisy birds and make a wide variety of noises, including yodels, guttural calls, gargled trills, and whistles. And, like other cuckoos, they give off a very strong odor.

A Flock of Guira Cuckoos © Jake Jacoby

Guira Cuckoos are omnivores and groups will forage together for insects, frogs, eggs, large arthropods such as spiders, crabs, etc., and small mammals such as mice, as well as the nestlings of small birds. Their beak is thick and has a downward curve, which is designed for eating meat. They belong to the same family as the Roadrunner.

Guira Cuckoo in the open field © Jake Jacoby

Guira Cuckoo courtships occur on the ground, with the male dancing around the female with wings open, crest raised, tail raised and feathers fanned out. These cuckoos are polyandrous (females mate with multiple males) and polygynous (males mate with multiple females). Breeding pairs preen each other and will defend their breeding territory during the mating season from any intruder. Guira Cuckoos build large, communal nests where up to 10 females lay as many as 25 eggs at a time. In an attempt to increase the chances of their own offspring surviving, the females will eject another’s eggs from the nest when nobody is looking. They do not behave aggressively in the communal nest and when the weather turns cold, they will huddle together and roost together at night as well.

Nests are constructed of large platforms of sticks built high in a tree. Often a nest used in previous years will be renovated and reused, and several females will lay their eggs in the same nest. Guira Cuckoos have a high rate of egg loss, as well as a high mortality rate for nestlings, due to the tossing behavior of the adults. Adults will eject eggs and young birds from the nest but this behavior is not fully understood. Up to 20 eggs can be laid in a group nest.

Guira Cuckoo in the cattle pastures © Jake Jacoby

Eggs are blue to greenish-blue and are covered in white chalky splotches and streaks. The incubation period is 12-13 days and the fledgling period varies from 5 to 6 days if the young are disturbed; and, 12 to 15 days in an undisturbed nest. Parental care will continue for about 3 weeks after the juveniles fledge.

Guira Cuckoo in the trees © Jake Jacoby

The Guira Cuckoos name comes from an indigenous Tupi Indian name which translates to “bird with the headdress”. The undoubtedly refers to the birds crest, which resembles an indigenous ceremonial headdress.