A shrinking home for endemic birds

17 Western Ghats species have smaller ranges than what experts at IUCN estimated

Lost world: Almost 88% of the habitat of the Nilgiri pipit has disappeared, according to researchers.

Birds endemic to the biodiverse Western Ghats appear to be in greater danger than they were thought to be, because the range of places they live in may have been overestimated.

Researchers from four American universities who analysed range maps used by the influential global authority, the International Union for Conservation of Nature (IUCN), found that for 17 of 18 bird species, the distribution was smaller than IUCN estimates.

The ‘Red List’ classifications of the IUCN serve to guide protection policies; ‘less vulnerable’ species receive a lower conservation focus. The study published in the journal

Biological Conservation , argues that IUCN overestimated the habitat of these bird species by up to 88%. Of the 18 species, habitats of 12 were overestimated by over 50%. Under the new model, 10 species could be bumped up on the IUCN scale, for a higher risk. An example is the Malabar grey hornbill which IUCN classifies as ‘Least Concern’ and believes is distributed across 2.3 lakh sq.km in Kerala and Karnataka. But when researchers used a spatial modelling technique, they found its range was just 43,060 sq. km, or, nearly 81% less than the estimates. This would put the bird in the ‘Near Threatened’ category. Again, the Nilgiri pipit appears to have lost 88% of its habitat, making it “endangered” rather than “vulnerable”.

The lead author of the study, Vijay Ramesh, a spatial and computational ecologist at the Cary Institute of Ecosystem Studies, who worked with scholars from Columbia, Cornell, and Duke universities, says underestimating threat and overestimating habitat reduces policy response. “Moving towards the 2030s and 2040s, if we are not aware of where exactly these birds are found today, there is very little you can do later on,” he says.

IUCN uses expert sightings and other records, while the study used land cover, forest type (satellite imagery), temperature, precipitation and ‘citizen science’ using the eBird online birding checklist.