In an effort to shape future conservation strategies for the sloth bear, scientists from the Wildlife Conservation Society-India Program and the Centre for Wildlife Studies are working on developing distribution maps of the endangered species in India.
Despite being on the International Union for Conservation of Nature (IUCN) Red List of threatened species, negligible information is available about the distribution of sloth bears across the country.
Sloth bears are found in India, Nepal, Sri Lanka and Bhutan. In Bangladesh, their existence is not certain because the last records about their presence in the country date back to the late 1990s. Due to loss of habitat and poaching, their population has declined by 30-49% over the past 30 years.
Using a ‘multi-scale’ approach towards mapping these mammals, the researchers estimated the habitat range of sloth bears across India as covering 2.97 million sq. km of area; at the landscape scale in the Western Ghats region of Karnataka, the habitat range covers 38,540 sq. km.
“There are many non-protected landscapes where a lot of species live, such as wolves, sloth bears and leopards. Some sort of prioritisation needs to be given to such areas, so that they are not used for infrastructure projects,” said Mahi Puri, lead author of the paper, describing the work in the journal Diversity and Distributions.
Puri added that apart from a few animals such as the tiger and the elephant, there are no population estimates for animal species.
The study by the scientists suggested that nationwide, sloth bear densities are greatest in protected areas and areas with dense or deciduous forest cover. While the animals also occupy barren areas and scrublands, cultivated landscapes seem to repel sloth bears.
The study further found that they avoid areas with human inhabitants or farmland, and many of them have found sanctuary in reserves set up to protect tigers. The authors proposed that the sloth bear could be considered a potential ‘umbrella species’, a species whose conservation allows for the preservation of a much larger spectrum of biodiversity in their habitats.
Although no reliable large-scale population estimates exist for sloth bears, guesstimates hint there are 20,000 or fewer sloth bears, and thus less than 10,000 adults, according to the IUCN.
“These distribution maps were created in 2005 after considering only select protected areas and by using radio collars on the bears and extrapolating the numbers across the country. There are much more reliable methods now and so data needs to be analysed,” Puri explained.
The scientists used a grid-based occupancy approach to determine sloth bear distribution patterns and at the nationwide scale, they used data from questionnaire surveys of field experts. At the landscape scale, they conducted field surveys of bear signs. Using occupancy modelling methods or using repeated observations.
The researchers developed a human cultural tolerance index using information on socio-cultural practices, conservation history, hunting practices and the efficacy of anti-hunting law enforcement in various states. This index can be used to categorise people as the most, least and medium tolerant to sloth bears’ presence. The authors found that while Rajasthan and Gujarat rank high on the tolerance index, the seven north-eastern states, Chhattisgarh and Jharkhand are the least tolerant to the presence of sloth bears.
“Our study underlines the need to integrate human-modified areas with existing conservation landscapes. Protection of widespread species such as the sloth bear in other landscapes may complement current conservation strategies for large mammalian communities,” the authors of the study concluded