The endangered Banasura laughingthrush survives across only 50–60 sq km of high-altitude habitat in and around Wayanad, where recurring forest fires, landslides, climate change and a proposed twin tunnel road are increasing pressure on one of the Western Ghats’ most restricted bird species, according to the first quantitative study of its distribution, occupancy and abundance.
The study, published in Nature Scientific Reports, estimates the bird’s population at 1,000–1,500. Researchers recorded it only in montane shola forests across three isolated hill ranges: Camel’s Hump Mountain, Banasura Hills and Brahmagiri Hills. Despite extensive surveys, the bird was not detected at Kurichyarmala, where earlier records had not been confirmed.
The research team surveyed 54 grids and 157 spatial replicates across four hill ranges, covering 89.5 km over 84 man-days. They recorded 316 detections, with the species found in 35 grids. Occupancy and detection rates declined from south to north, with the highest levels at Camel’s Hump Mountain, followed by Banasura Hills and Brahmagiri Hills.
Elevation, slope, shrub cover and vegetation productivity influenced where the bird was found. Although it was recorded at elevations ranging from 1,400 metres to above 2,300 metres, occupancy and abundance increased markedly above 1,700 metres. However, the amount of available habitat narrowed sharply at higher elevations, falling from 38.97 sq km at 1,400–1,500 metres to 5.05 sq km at 1,900–2,000 metres and just 0.05 sq km above 2,300 metres.
N S Sujin, one of the researchers, said the bird’s small range made it highly extinction-prone because range size is a strong predictor of extinction in terrestrial species. The species is among the rarest and least-studied birds in the Western Ghats, he said, partly because its habitat consists of difficult terrain that is frequently covered by heavy rain and mist during the monsoon.
The Brahmagiri population may number only around 20 birds, according to the researchers’ estimate. Its small size, isolation and limited habitat could increase its exposure to demographic fluctuations, inbreeding, reduced genetic diversity and predation.
Human-caused fires are a major threat. Using satellite data and field observations, the study mapped 3,020.4 hectares of burnt area in and around the bird’s habitat between 2018 and 2025. The worst years were 2019, when 1,024.7 hectares were burnt, and 2020, when the burnt area reached 1,030.3 hectares.
The study says fires destroy shola vegetation, open the forest canopy, reduce connectivity between habitat patches and gradually convert forest into grassland. The researchers also flagged new road and tunnel projects proposed through the landscape, which they described as geologically ancient and inherently prone to landslides. Such activity, the study said, could further worsen habitat degradation and slope instability.
The Union environment ministry’s expert appraisal committee made scientific monitoring of the bird a mandatory condition when it granted environmental clearance to the Anakkampoyil-Kalladi-Meppadi tunnel project in May 2025. The report does not establish whether the monitoring condition has already produced new findings.
Nearly 99% of the bird’s range lies outside the protected area network. The researchers have recommended declaring Camel’s Hump Mountain a national park and expanding Malabar Wildlife Sanctuary to include Banasura Hills before upgrading it to a national park. They have also called for minimal human interference, stronger fire management and restrictions on tourism.