Similarly, a survey in 2017 put the number of crocodiles in the Sunderbans between 150 and 205.

However, the census also pointed out that the crocodiles are at the risk of extinction due to seven reasons, including deaths of baby crocodiles in fishing nets, movement of water vessels in the Pashur river, and dumping of industrial waste in the river.

Professor Abdullah Harun Chowdhury of the environmental science department at Khulna University, said, “The forest department should conduct a wildlife census periodically to enumerate wild animals like wild buffaloes, crocodiles, tigers and leopards in the Sunderbans."

The census can also help the Bangladesh government in adopting a proper wildlife management system in the Sundarbans, he said.

Hawladar Azad, officer-in-charge of Karamjal Wildlife Breeding Centre in East Sundarbans, said the authorities conducted a wildlife census of deer, monkeys and otters in 1997.

According to the 1997 census, there were more than 100,000 deer, 40,000 to 50,000 monkeys, 20,000 to 25,000 pigs and 20,000 to 25,000 otters.

However, there has been no census of water monitors, pythons, turtle, birds and other animals to date.

Sheikh Faridul Islam, chairman of Save the Sundarbans Foundation, said, “We must find out the actual number of wildlife animals inhabiting the Sunderbans. The forest department should take necessary steps in this regard."

The number of wildlife animals could also fall due to the movement of tourists and vessels in rivers inside the Sundarbans, he said.

Mihir Kumar Do, forest conservator (Khulna circle), said that they do carry out "smart patrolling" using GPS for protecting the wildlife in the Sunderbans.