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Camera traps have photographed the rare Mayr’s forest rail (Rallicula mayri) in the Indonesian part of New Guinea. The poorly studied bird species had last been recorded in the Foja Mountains in 2007.
The images were captured in September 2023 as part of Expedition Cyclops, an international research project led by the Indonesian NGO Yappenda. The results were published in 2026 in a study of birdlife along the elevation gradient of the Cyclops Mountains.
The six images show a small, chestnut-brown bird moving across a forest floor covered with leaves and moss. The research team led by James Alexander Kempton attributed the images to three independent events at two sites. Mayr’s forest rail was thus documented in the Cyclops Mountains for the first time since 1928—the mountain range after which its German name is derived.
An unexpected discovery
New Guinea is the world’s largest tropical island and one of its most biodiverse yet least thoroughly studied regions. Its birdlife is particularly diverse. Although birds there are better studied than other animal groups, new species continue to be discovered and known ranges expanded. In 2025, Ptilorrhoa urrissia, a new species of jewel-babbler, was scientifically described. Because field research is so difficult, automated methods such as camera traps and acoustic recorders are becoming increasingly important.
Image: Expedition Cyclops, from Kempton et al. (2026), Fig. 2A, CC BY 4.0; cropped
The expedition’s camera traps had originally been set up primarily to survey ground-dwelling mammals. One of the main objectives was to search for Attenborough’s long-beaked echidna (Zaglossus attenboroughi), for which no documented record had been available for more than 60 years.
The team installed 73 automatic cameras at elevations ranging from 143 to 1,963 meters. The devices remained in operation between June 2023 and March 2024 along animal trails, on ridges, and at sites showing signs of mammals. Together, they logged 11,869 camera-trap days and produced more than 38,000 images.
In addition to mammals, the cameras also recorded numerous birds. The researchers registered 22 bird species in a total of 1,696 independent records. These included two species that were considered “lost” at the time because there had been no known photographic, acoustic, or genetic records for more than ten years: Mayr’s honeyeater (Ptiloprora mayri) and Mayr’s forest rail.
Mayr’s forest rail was photographed at elevations of 1,700 and 1,746 meters, placing it within its already known elevational range. What made the records remarkable was therefore not so much their elevation as their location in the Cyclops Mountains, where the species had last been documented 95 years earlier.
Mayr’s forest rail is already the expedition’s third publicly announced rediscovery. The team had previously photographed Attenborough’s long-beaked echidna again after more than six decades. Mayr’s honeyeater, for which no documented record had been available since 2008, was also captured by the cameras.
The findings show how little may be known even about a relatively small mountain range. The Cyclops Mountains are among a series of isolated mountain ranges in northern New Guinea that rise like ecological islands from the surrounding lowlands. Distinct animal and plant populations have been able to evolve within them over long periods.
No record in the Cyclops Mountains since 1928
The history of Mayr’s forest rail is closely linked to the German-American ornithologist Ernst Mayr. During an expedition, he collected several specimens in the Cyclops Mountains in 1928, which Ernst Hartert used as the basis for his scientific description of the species in 1930. The specific epithet mayri commemorates Mayr.
Map: Demis, Public Domain, via Wikimedia Commons, edited and annotated
After that, Mayr’s forest rail did not disappear completely from the scientific record. It was later recorded in the species’ three other known ranges as well: the Foja, Bewani, and Torricelli Mountains. However, it had not been scientifically documented in the Cyclops Mountains themselves since Mayr’s expedition.
Until then, the species’ most recent confirmed record had come from the Foja Mountains. An adult female was photographed there in June 2007. A specimen had already been collected and an audio recording made there in 2005. Thus, around 16 years elapsed between the 2007 photograph and the new camera-trap images from September 2023.
The researchers describe their images as the first photographs of Mayr’s forest rail. However, the Search for Lost Birds initiative points to the image of the female temporarily captured in 2007. The six images from the Cyclops Mountains are therefore probably the first camera-trap photographs of the species—and, together with the 2007 photograph, the only photographic records of Mayr’s forest rail known to date.
Why Mayr’s forest rail is so difficult to find
The long gaps between records are probably due at least in part to the way Mayr’s forest rail lives. The small, dark-colored bird spends most of its time on the ground in dense montane rainforests. Among ferns, mosses, leaf litter, and dense undergrowth, it is easily overlooked even at close range.
Image: Expedition Cyclops, from Kempton et al. (2026), Fig. 2B, CC BY 4.0; cropped
The inaccessibility of its habitat is another factor. The Cyclops Mountains, which cover around 250 square kilometers, rise steeply from New Guinea’s northern coast to approximately 1,970 meters. High rainfall, a lack of trails, and some very steep slopes make biological surveys difficult. The higher northern slopes in particular had received little ornithological study before the 2023 expedition.
To reach the remote study areas, the expedition team first had to travel for several hours in off-road vehicles and then continue into the mountains on foot. Malaria, infections, leeches, and the difficult terrain made the work even harder. The knowledge of the local Indigenous community contributed substantially to the expedition’s success, as community members identified suitable animal trails and camera-trap sites.
Camera traps are therefore particularly well suited to secretive ground-dwelling species. They can remain in the forest for months and record animals without researchers having to be present continuously. However, the method has limitations: Of the 182 bird species now known from the Cyclops Mountains, the cameras recorded only 22. Species that spend most of their time in the canopy, in particular, rarely enter the field of view of devices installed close to the ground. Camera traps therefore do not replace traditional ornithological surveys, but they can complement them.
Poorly studied—and classified as Least Concern
To this day, little is known about Mayr’s forest rail. Its four known populations occur in isolated mountain ranges in northern New Guinea. The number of animals living there and the size of the individual populations have never been determined. It is also unclear whether gene flow still occurs between the geographically separated populations.
Little information is also available about its diet, reproduction, and social behavior. The new camera-trap images merely confirm that the species still occurs in the Cyclops Mountains. They do not permit any conclusions about the size or condition of the population there.
Image: AI reconstruction of a female Mayr’s forest rail based on Taylor and van Perlo (2010)
Nevertheless, the IUCN lists Mayr’s forest rail as Least Concern (LC). Although the species has a restricted range, there is currently no evidence of a substantial decline in its population or habitat. The number of mature individuals has not been determined but is not believed to be low enough to fall below the threshold for classification as threatened. The population trend is considered probably stable, primarily because no major declines or specific threats are known. The remote montane forests are also considered comparatively unlikely to be threatened by logging.
However, even the estimates of its abundance are largely based on old and sporadic observations. Mayr’s forest rail was once described as common in the Bewani and Torricelli Mountains, but this assessment was based on only seven specimens from 1966. Apparently, no subsequent targeted searches took place there. From the Cyclops Mountains, only four historical voucher specimens were known before the new images; during fieldwork, the species was not found in 1992. In the Foja Mountains, it was considered common or rather rare depending on the site between 2005 and 2009.
Mayr’s forest rail may be more common locally than the few records suggest. However, this has not been established. Its classification as Least Concern therefore primarily means that there are currently no concrete signs of a steep population decline—not that its populations have been thoroughly studied or that their long-term future is certain.
Future risks cannot be ruled out either. In Indonesian Papua, pressure on forests is increasing because of agriculture, plantations, mining, and the extraction of other raw materials. Whether and to what extent this also affects Mayr’s forest rail habitats at higher elevations remains unclear. Yappenda therefore supports local Indigenous communities in efforts that include securing their land rights and preserving cultural traditions closely linked to forest conservation.
One record, many unanswered questions
The 2023 camera-trap images demonstrate that Mayr’s forest rail still occurs in the Cyclops Mountains. Naturally, the few images reveal very little about the condition of the population. It remains unclear how many animals live there, how widely the species is distributed, and what habitat requirements it has. Nor is it known how changes to montane forests or climate change might affect it.
Answering these questions would require long-term studies in other parts of the mountain range. In addition to more camera traps, audio recordings, genetic samples, and targeted observations could help researchers better understand the species’ distribution, behavior, and population structure.
The new record therefore merely closes a long gap in the documentation. Nearly 100 years after its scientific description, research into Mayr’s forest rail is still in its infancy.
Sources
- Bergen, M. (2026, July 29). FOUND: Mayr’s Forest Rail Rediscovered in Indonesia’s Cyclops Mountains. Search for Lost Birds. https://searchforlostbirds.org/news/found-mayrs-forest-rail-rediscovered-in-indonesias-cyclops-mountains
- BirdLife International. 2017. Rallicula mayri. The IUCN Red List of Threatened Species 2017: e.T22692303A118088528. https://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T22692303A118088528.en
- Kempton, J. A., Balázs, A., Bessoran, Y., et al. (2026). New avian records along the elevation gradient of the Cyclops Mountains, New Guinea, revealed by camera trapping. Birds, 7(2), Article 27. https://doi.org/10.3390/birds7020027
- Taylor, B., & van Perlo, B. (2010). Rails: A guide to the rails, crakes, gallinules and coots of the world. Christopher Helm.
About the author: Doreen Fräßdorf
Doreen Fräßdorf is the author and publisher of artensterben.de. She researches and writes about extinct and endangered species in the modern era, with a focus on red lists, scientific studies, historical sources, and current conservation efforts. The goal is a clear, evidence-based overview of biodiversity loss and species protection.
She is also the author of a non-fiction book about extinct modern-era mammals.
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