Guwahati: The slender-billed vulture, one of three critically endangered vulture species in India, has experienced catastrophic population declines of over 97% since the 1990s. Essential scavengers in the ecosystem, these vultures face threats like habitat destruction, food scarcity, and poisoning. Once common across Southeast Asia, the species is now extinct in countries such as Malaysia and Thailand, making conservation efforts in India critical.
A comprehensive study by researchers from Rajiv Gandhi University in Doimukh which mapped the habitat suitability for the critically endangered Slender-Billed Vulture(SBV) (Gyps tenuirostris) across Arunachal Pradesh found only 0.12% is categorized as “extremely suitable” for SBVs, located mainly in low-elevation areas like East Siang, Lohit, and Namsai districts.
Published in Current Science journal, the study used predictive MaxEnt modeling to identify the distribution and suitability of habitats for the vulture, emphasizing the limited availability of areas that meet the species’ survival needs.
The study done from 2016 to 2019, focused on Arunachal Pradesh, a biodiversity hotspot with diverse ecosystems and rugged terrain. Researchers surveyed 850 km of road routes, documenting 19 georeferenced points of slender-billed vulture occurrences. The MaxEnt model was used to analyze these data points against environmental variables, including elevation, land cover, temperature, precipitation, vegetation indices, human population density, and livestock density.
“Around 97% of the state’s terrain was classified as unsuitable for SBV habitation due to factors like elevation and dense forest cover” the study found out.
An additional 350.91 sq km (0.43%) was considered “highly suitable,” mostly in foothills and open plains near the Assam border.
Environmental factors influencing habitat suitability
The model highlighted that elevation, influencing 63% of habitat suitability, is the primary factor affecting vulture distribution. These vultures favored low-lying areas with open landscapes and sparse vegetation, as these regions offer greater access to carrion. Other significant variables include:
Land Cover and Vegetation: Open land, croplands, and barren areas were favorable, while dense forests were unsuitable for foraging.
Climate: Moderate temperatures above 18°C and consistent precipitation levels were ideal, whereas extreme variations in temperature or precipitation reduced suitability.
Human and Livestock Density: Though lesser factors, areas with moderate livestock density supported SBV habitation by providing a consistent food source.
Conservation implications and recommendations
The study identifies critical areas where conservation efforts could be concentrated to support SBV populations. Protecting open landscapes and reducing disturbances in low-elevation zones are recommended. Researchers have suggested for having community awareness programs to educate locals about the ecological role of vultures to build community support. Further studies are needed in predicted suitable areas lacking SBV presence to identify possible barriers, such as food scarcity or human interference.
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