New Delhi, March 14: India tops a list of 24 countries in which at least 40 per cent of large herbivores and carnivores are threatened, an international team of wildlife biologists has said, iterating a call for fresh conservation efforts.

The scientists said India, among these countries, has the largest number of terrestrial megafauna species - carnivores heavier than 15kg or herbivores above 100kg - but 18 of these 28 species are vulnerable, endangered, or critically endangered under International Union for Conservation of Nature criteria.

Such megafauna typically need large habitats and could serve as "umbrellas" to conserve other species and ecosystems, the 43-member team of wildlife experts from Australia, China, India, Kenya, the US among other nations said in a report published today in the journal Bioscience.

The tiger, elephant and rhinoceros are among India's threatened megafauna, while the nilgai, kiang and the leopard are among non-threatened species. China's threatened megafauna include the giant panda, Asian elephant and the snow leopard.

"India has achieved significant wildlife conservation successes, evident through the numbers of tigers or rhinos, but multiple threats to these animals persist," said Varun Goswami, a team member senior scientific consultant with the Wildlife Conservation Society, Bangalore. "The conservation efforts need to be sustained."

The 43 scientists had last year called for globally coordinated efforts to halt the threat to megafauna, warning that 59 per cent of the world's largest carnivores and 60 per cent of its largest herbivores face extinction.

William Ripple, professor of ecology at Oregon State University in the US, and his collaborators issued the call after analysing trends facing large carnivores such as wolves, lions, tigers and bears, besides herbivores like elephants, rhinos, tapirs and zebras. The scientists had listed expansion of farm and livestock areas, illegal hunting, deforestation and human population growth among the biggest threats.

Their new report is intended to allay concerns that any focus on megafauna species might undermine efforts to save smaller species or their wider ecosystems themselves.

"We want to emphasise the protection of megafauna is not in any conflict with the conservation of smaller species or ecosystems," Goswami said.

The establishment of tiger reserves through core protected areas and the resources earmarked for tiger conservation have, for example, helped safeguard many other species and habitats across India, Goswami said.

Ripple and his collaborators have said their call for urgent action issued last year was "necessary because despite being among the most cherished species by the public, many megafauna populations and species are sliding towards extinction."