Introduction
The Undulated Tinamou (Crypturellus undulatus) is a medium-sized, ground-dwelling bird in the tinamou family, Tinamidae. It occurs widely across northern and central South America, where its far-carrying whistle is often heard more readily than the bird is seen. Despite its largely terrestrial habits, it can make a sudden, noisy flight when flushed.
Physical Description
The Undulated Tinamou is approximately 28–32 cm long. It has a compact, rounded body, a short tail and sturdy legs suited to walking through dense vegetation. The upperparts are greyish brown to olive-brown, with fine dark vermiculation that is usually subtle at a distance. The throat is whitish, while the breast and belly are pale grey, creamy or buff, with fine barring or vermiculation on the flanks and lower body. The bill is dark, and the legs are generally greyish to yellowish green.
Males and females are broadly similar in appearance, and reliable external sexual differences are not normally used for field identification. Juveniles are less well documented than adults and may appear duller and more heavily marked. As with other tinamous, the body is cryptically coloured, helping the bird blend into leaf litter, woodland shade and scrub.
Range and Habitat
The species is resident in eastern and northern South America. Its range extends from southern Venezuela, eastern Colombia and eastern Ecuador through Amazonian Brazil, Bolivia and Paraguay to northern Argentina. It also occurs in a variety of regions within Brazil, including the Amazon Basin, Cerrado, Pantanal and other wooded landscapes.
The Undulated Tinamou uses humid and seasonally dry lowland forest, gallery forest, river margins, woodland, forest edges, secondary growth and some savanna-woodland mosaics. It is also recorded on large river islands and in dry forest and scrub where sufficient cover remains. Available distribution data place it mainly at low elevations, generally below about 900 m, although local records may extend higher.
It is not considered migratory. Geographic variation is recognised among several subspecies, with differences in the tone of the upperparts, the strength of barring and the colour of the underparts. These differences can be difficult to assess in the field.
Behaviour and Diet
The Undulated Tinamou is secretive and usually walks quietly through ground vegetation, foraging alone or in pairs. It may remain motionless when approached, but a close disturbance can produce a short, explosive flight. It is most often detected by its clear, fluted whistle, commonly given in a repeated three- or four-note phrase. Calling may occur during the day and at night, with activity often noticeable around dawn and dusk.
Its diet includes fallen fruit, seeds and small invertebrates such as insects. The balance of plant and animal food varies with habitat and season. By consuming fruit and seeds, the species may contribute to the movement of plant propagules, although its specific importance as a seed disperser is not well quantified.
Breeding and development
Like other tinamous, the Undulated Tinamou has a reversed division of parental roles. The female lays the eggs, while the male undertakes most or all of the incubation and cares for the young after hatching. The nest is a shallow depression on the ground, usually concealed among leaves or other vegetation. Clutches commonly contain several eggs, and the eggs are noted for their smooth, glossy appearance and variable vinaceous, pinkish or greyish colouring.
Incubation has been reported to last about 17 days in captivity. The chicks are precocial, leaving the nest soon after hatching and following the attending male while feeding. Detailed information on nesting success, chick survival and the timing of breeding varies geographically and remains limited.
Identification Tips
- Look for a stocky, short-tailed bird about 30 cm long moving quietly through woodland or dense ground cover.
- The combination of greyish-brown upperparts, a pale throat, finely marked underparts and grey or yellowish-green legs is useful, although the markings can be difficult to see.
- The species is more often heard than seen. Its clear, mournful whistle usually consists of three or four fluted notes, with the final note often rising or strongly accented.
- When flushed, it leaves the ground abruptly with rapid wingbeats and a loud clatter, then usually disappears quickly into cover.
- In areas where it overlaps with the Red-legged Tinamou (Crypturellus erythropus), the Undulated Tinamou generally has greyish or yellowish-green legs rather than distinctly red legs. Calls and habitat should also be considered because plumage differences can be subtle.
Conservation Status
The Undulated Tinamou is currently assessed as Least Concern on the IUCN Red List. This classification reflects its broad geographic range and continued occurrence across many habitats, not an absence of local threats.
Habitat loss and fragmentation caused by agricultural expansion, deforestation, woodland clearance and other land-use changes can reduce suitable cover. Hunting may also affect local populations, particularly where the species is accessible and occurs at low densities. Research from the Brazilian Pantanal has documented seasonal calling patterns and highlighted the value of acoustic monitoring for a secretive species whose population status is difficult to assess visually.
Maintaining connected forest and woodland, protecting riverine and gallery habitats, managing hunting pressure and improving monitoring are appropriate conservation measures. The global population size is not reliably quantified, so precise population figures should not be inferred from the species’ Least Concern status.
Frequently Asked Questions
Where does the Undulated Tinamou live?
It occurs across much of northern and central South America, including parts of Venezuela, Colombia, Ecuador, Brazil, Bolivia, Paraguay and northern Argentina. It uses forest, woodland, river margins, scrub and other habitats with adequate ground cover.
Is the Undulated Tinamou migratory?
No. It is generally regarded as a resident species rather than a regular migrant, although local movements may occur in response to habitat conditions.
What does the Undulated Tinamou eat?
Its diet includes fallen fruit, seeds and small invertebrates, especially insects. The relative importance of these foods varies with season and habitat.
How can the species be identified by sound?
It is recognised by a clear, fluted whistle commonly delivered as three or four notes. The call often carries a considerable distance through woodland and is frequently the first evidence that the species is present.
Does the male or female incubate the eggs?
The male incubates the eggs and cares for the chicks. The female lays the eggs, making this an example of the reversed parental roles found in tinamous.
Is the Undulated Tinamou threatened?
It is currently classified as Least Concern, but habitat clearance, fragmentation and hunting can cause local declines. Its secretive behaviour also makes population monitoring difficult.
References
- BirdLife International. n.d. Undulated Tinamou Crypturellus undulatus Species Factsheet. BirdLife Data Zone. Available at: https://datazone.birdlife.org/species/factsheet/undulated-tinamou-crypturellus-undulatus (accessed 8 September 2026).
- Gill, F., Donsker, D. and Rasmussen, P. (eds). 2026. IOC World Bird List, version 15.2. International Ornithologists’ Union. Available at: https://www.worldbirdnames.org/ (accessed 8 September 2026).
- Davies, S. J. J. F. 2002. * ratites and Tinamous*. Oxford University Press. [The book covers tinamou morphology, ecology and breeding biology.]
- Hilty, S. L. 2021. Birds of Northern South America: An Identification Guide. Princeton University Press. Species account for the Undulated Tinamou, Crypturellus undulatus.
- Pérez-Granados, C., Schuchmann, K.-L. and others. 2020. Vocal behavior of the Undulated Tinamou (Crypturellus undulatus) over an annual cycle in the Brazilian Pantanal: new ecological information. Biotropica. https://doi.org/10.1111/btp.12742.
- Schelsky, W. M. 2004. Conservation of Amazonian tinamous. Ornitologia Neotropical, 15 (Supplement), 317–321. Available at: https://sora.unm.edu/sites/default/files/journals/on/v015s/p0317-p0322.pdf (accessed 8 September 2026).
- Del Hoyo, J., Collar, N. J. and others. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World, Volume 1: Non-passerines. Lynx Edicions and BirdLife International.
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