Red-billed Curassow (Crax blumenbachii)

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Image of a Red-billed Curassow in its natural habitat
Birds Curassow

Introduction

The Red-billed Curassow (Crax blumenbachii) is a large, ground-feeding member of the curassow family, Cracidae. Endemic to Brazil, it is associated with the lowland Atlantic Forest and is one of the region’s most threatened large frugivorous birds. The species has disappeared from much of its former range because of habitat loss, forest fragmentation and hunting.

Physical Description

The Red-billed Curassow is a large, heavy-bodied bird, reaching about 84 cm in length and weighing approximately 3.5 kg, although measurements vary between individuals and sources.

Adult males are predominantly glossy black, with contrasting white lower underparts and a conspicuous red bill base. They also have a prominent, curled crest and dark legs. The red bill base is most noticeable in the male and may be accompanied by small fleshy ornaments during the breeding period.

Females are distinctly different in appearance. Their wings and lower back are barred or vermiculated with rufous and white, while the crest is more strongly barred. The underparts are generally rufous, the bill is darker than the male’s, and the legs are reddish. This pronounced sexual dimorphism is useful for identification.

Young birds resemble females more closely than adult males and develop adult plumage progressively as they mature.

Range and Habitat

The Red-billed Curassow is endemic to Brazil. Its original distribution extended through lowland Atlantic Forest from southern Bahia southwards through Espírito Santo and eastern Minas Gerais to Rio de Janeiro. It has been lost from much of this range, and Rio de Janeiro is considered to have only historical or reintroduced occurrences.

Remaining and re-established populations are associated with isolated forest remnants in Bahia, Espírito Santo and Minas Gerais. The species favours warm, humid lowland forest, particularly primary forest and mature secondary forest with dense undergrowth. Available records generally place it at low elevations, mostly below about 500 m.

It is non-migratory. Because it depends on large, connected forest remnants and is reluctant to cross open agricultural landscapes, fragmentation can isolate populations and restrict natural recolonisation.

Behaviour and Diet

Red-billed Curassows spend much of their time on the forest floor, where they search through leaf litter for fallen fruits, seeds, tender leaves and small animal prey such as insects, spiders, centipedes and snails. They may also take fruit directly from vegetation before carrying it to the ground.

Recent research has documented a diverse fruit and seed diet and supports the species’ role as a seed disperser. Seeds recovered from droppings have included many Atlantic Forest plant species, suggesting that the curassow can contribute to forest regeneration and the movement of seeds away from parent trees.

Individuals may occur alone, in pairs or in small groups. The species is generally quiet and inconspicuous, despite its size, and often retreats into vegetation or flies into low trees when disturbed. Its low-frequency calls and other vocalisations are associated with communication and breeding behaviour, but the details of its social system and seasonal activity remain incompletely understood.

Breeding information from the wild is limited. Captive observations indicate that clutches usually contain two eggs, with incubation lasting about 30 days. Chicks leave the nest soon after hatching and remain dependent on adult birds during their early development.

Identification Tips

  • Look for a large, heavy-bodied forest bird that spends much of its time walking on the ground.
  • Adult males are glossy black with white lower underparts, a curled crest and a red bill base.
  • Females are much more patterned, with rufous-and-white barring on the wings and back, a barred crest and rufous underparts.
  • The strong difference between male and female plumage is one of the species’ most useful identification features.
  • In its range, the combination of large size, forest-floor behaviour and the male’s red bill base helps separate it from other Atlantic Forest cracids.

Conservation Status

The Red-billed Curassow is listed as Endangered on the IUCN Red List. The current Brazilian assessment identifies continuing population decline, with fewer than 2,500 mature individuals inferred across the remaining and reintroduced populations.

The principal threats are the loss and fragmentation of lowland Atlantic Forest, hunting for meat and the isolation of small populations. Habitat degradation can also reduce food availability and make relict populations more vulnerable to local extinction.

Important conservation measures include protecting remaining forest, improving enforcement against hunting, restoring habitat corridors, monitoring wild populations and maintaining genetically managed captive populations. Brazilian conservation programmes have used captive breeding and reintroduction to restore the species in areas where it had disappeared, including parts of Minas Gerais and Rio de Janeiro. Reserves such as Reserva Biológica de Sooretama and Reserva Natural Vale in Espírito Santo provide important habitat for the species, while the Parque Estadual do Rio Doce has been the focus of more recent reintroduction work.

Frequently Asked Questions

Where does the Red-billed Curassow live?

It lives in Brazil’s Atlantic Forest, especially lowland and mature forest remnants in Bahia, Espírito Santo and eastern Minas Gerais. Some populations have also been reintroduced into parts of its former range.

Is the Red-billed Curassow endangered?

Yes. The species is classified as Endangered by the IUCN because its population continues to be affected by habitat loss, fragmentation and hunting.

What does the Red-billed Curassow eat?

Its diet includes fallen fruits and seeds, as well as leaves and small invertebrates. Its varied fruit diet means it can play an important role in dispersing seeds through the forest.

How can male and female Red-billed Curassows be distinguished?

Males are mainly glossy black with white lower underparts and a red bill base. Females are rufous, brown and white, with strongly barred wings, back and crest.

Does the Red-billed Curassow migrate?

No. It is a non-migratory forest bird. Its movements are mainly local and are influenced by food availability, breeding and the condition of the surrounding forest.

What is being done to protect this species?

Conservationists are protecting forest remnants, reducing hunting, restoring habitat, monitoring populations and using captive breeding and reintroduction programmes to re-establish the species in suitable protected areas.

References

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