A new species of bird has been found in an Amazonian national park - it's almost unafraid of humans

In the mountains of the Serra do Divisor National Park (SDNP) in western Brazil, ornithologists have described a new species of tinamou in the genus Tinamus - called Tinamus resonans. However, this ground-dwelling, almost flightless forest dweller may already be in danger of extinction. The work is published in the journal Zootaxa.

The unusual bird was first spotted... by ear. In autumn 2021, a member of the expedition recorded an unfamiliar song in the undergrowth of the Serra do Divisor. Scientists described it as an "unusual acoustic phenomenon": the voice seemed to dissolve into the forest, creating a deceptive sense of distance and direction of sound. The song resembled the vocals of other tinamou, but did not match any known species.

In the following years, researchers heard the voice several more times, but the dense vegetation, steep slopes and echoing sound made it impossible to determine where exactly the bird was singing from. It wasn't until November 2024 that the team managed to "pull" the performer into the light using a playback of his own song. It turned out that the source of the strange echo is a small, poorly flying bird with a dark, almost slate-grey "mask" on its head and a brownish-red lower body.

Behaviour was also unusual.

"In direct contact, individuals showed no avoidance reactions and seemed surprisingly tame, as if they did not perceive humans as potential predators. The birds calmly and slowly crossed open areas of undergrowth without any noticeable signs of wariness - a behaviour in stark contrast to the usually very fearful Tinamus," the study authors wrote.

The new species was named Tinamus resonans - from the Latin resonare, "to respond, sound, resonate," after the characteristic effect of its voice in the forest.

Additional observations revealed that Tinamus resonans is only found in a very narrow altitudinal zone.

"The species was recorded exclusively on steep forest slopes in the transition zone between sub-montane and low-montane forest at altitudes of approximately 310 to 435 metres above sea level," the researchers said.

This site is characterised by a dense, continuous carpet of fine roots and fallen leaves on poor, quartzitic sandstone soils. The birds move along this network of roots to find food.

During the entire observation period, the scientists managed to record only 15 individuals. Using spatial analysis and modelling of suitable habitats in GIS, they estimated the total population size at around 2,100 individuals. All specimens collected for detailed study were females. The sex of the other birds observed was difficult to ascertain, as many Tinamus species have males and females coloured similarly.

The authors suggest that the absence of males in the type series is related to the behavioural peculiarities of Tinamus:
females, as a rule, occupy a dominant position and more often respond to playbacks in defence of territory. Therefore, they are the first to respond to the audio bait, which creates a bias in the sampling.

Formally, the habitat of Tinamus resonans is entirely within the national park. But the status of this area could change. According to the authors, Serra do Divisor is exposed to serious political and economic risks: proposals are being considered to change its status from a national park to an "environmental protection zone", where a much wider range of economic activities are allowed.

In addition, road and railway construction and the development of mining projects are planned in the region.

For a new species, this combination of factors - small numbers, narrow range and almost no fear of humans - creates a very high risk of rapid extinction. Some researchers are already comparing the situation of Tinamus resonans to that of the dodo on the island of Mauritius, which disappeared shortly after humans arrived there.

The authors of the paper call for increased protection measures not only for Tinamus resonans, but also for the Serra do Divisor ecosystem as a whole. One possible way is to develop ecotourism, which can both contribute to the conservation of the unique fauna and generate income for local communities.