Wildlife biologists and legal experts say it is "illegal" to shift the leopard until it becomes a threat to the people in the neighbouring areas. They recommend community involvement in developing a programme for co-existence like the one at Mumbai's Sanjay Gandhi National Park.

Ritwick Dutta, an environmental lawyer, has already sent a notice to the Delhi government highlighting that the effort violates the wildlife protection act. The notice, sent to the chief wildlife warden under Section 55(C) of the act, says a Schedule-I wild animal can be captured only if it has "become dangerous to human life or so disabled or diseased as to be beyond recovery". The warden has also not passed an order in writing under Section 11(a) stating the reasons for the move, it added.

"This leopard is inside a forest and is feeding on wild prey. There have been plenty of leopards in Delhi, both in the Aravali belt and the Yamuna Khadar area," said Neha Sinha, a wildlife conservationist. "We need to co-exist by adopting simple avoidance behaviours like not leaving garbage out in the wild, having well lit paths, and spreading awareness."

VidyaAthreya, wildlife biologist and founder of Waghoba—a leopard conservation project, said the government's effort also violated the environment ministry's 2011 guidelines for human-leopard conflict management.

Under the guidelines, mere sighting of a leopard in the vicinity of human habitations does not necessarily mean that the animal has strayed from the forest and needs to be captured; its arbitrary removal may lead to increased conflict. "The focus should be on long-term solutions. These include better sanitation measures like proper garbage disposal in villages and towns so that feral pig and dog populations are kept under check and do not attract wild carnivores."

A wildlife official also said the leopard was not trying to come out of the forest. "Its belly is full as it has recently killed a bluebull. There is no reason to panic." The leopard seems to be a fit, 2.5-year-old male but its preying habits are slightly different, he added. "We didn't see it climb trees, which is a little unusual. But it doesn't seem to have any injury. The habitat has an entire herd of bluebulls and lots of hare. Moving him out is not a solution."

The forest department and ecologists like C R Babu, the brain behind DDA's Yamuna Biodiversity Park, have been striving for years to ensure that leopards come back to Delhi as it is an indicator of a thriving ecosystem and biodiversity. "We now have an integrated ecosystem in the park and there are plenty of herbivores. There is a need for a carnivore to maintain the ecological balance and complete the food chain. This leopard most likely came from the Shivalik range through the river corridor," said Babu.

The professor emeritus, DU, said the leopard should stay integrated in this ecosystem but the government had to decide. "To provide wild animals a large habitat, we need at least a 12-foot boundary fence and about 600 acres that will ensure that the park's area is close to the river. In the absence of these, we should let the government decide," Babu added.