A lower-than-expected number of male tigers has been identified as one of the key reasons behind the declining population of big cats in the world's largest mangrove forest Sundarbans. The improve the situation, the Bangladesh Forests Department (BFD) is planning to release some male tigers to the East Sundarbans where the male to female ratio of tigers is alarmingly low.

However, the number of Royal Bengal Tigers recorded rose to 114 in 2018, up from 106 found during the previous survey in 2015 in the Bangladesh part of the Sundarbans.

“We have identified some problems while conducting the tiger census in the Sundarbans.

"So, we have decided to release some male tigers in the eastern part to increase the tiger population,” he added.

The male-female tiger ratio is 5:1 in the West Sundarbans, while it is 1:10 in the East Sundarbans, Kabir said in reply to a query.

“We have already received allocation of Tk 48 crore under the tiger conservation project for conducting the tiger census between 2020 and 2021. The result will be disclosed in 2022,” he said.

The project has already been sent to the planning ministry through the environment, forests, and climate change ministry for final approval, he added.

“Radio collars would be put on male tigers so that we can monitor them through satellite transmitters after releasing them in the East Sundarbans. It'll help us know whether they are adjusting there or not,” Kabir said.  He also said tiger zones will be protected with a 60-km-long fence to prevent tigers from coming out of their natural habitat and raiding human habitations in search of food. “We will form committees for each kilometre of the fence comprising locals and forest officials. The committees will look after the nylon-made fence,” he added.

According to the BFD wildlife conservator, they will conduct genetic research and survey on prey animals too.

Earlier, the forest department conducted a census titled ‘Second Phase Status of Tiger in Bangladesh Sundarbans 2018’. The census on the critically endangered species of Bengal tiger was conducted by dividing the Sundarbans into three areas—Khulna, Bagerhat, and Satkhira.

The census in Satkhira was conducted in 2017. The following year, the census was carried out in Khulna and Bagerhat.

Forest officials said they conducted the camera trap census in 1,659 sq km of core tiger population areas in the Sundarbans. Of the total area, 1,208 sq km was in Satkhira, 165 sq km in Khulna, and 286 sq km in Bagerhat’s Shoronkhola.

Forest officials installed 491 cameras on trees at 239 points of the Sundarbans and collected 2,500 images of tigers during the 249-day survey.

According to the Tiger Census 2015, the tiger population was only 106 in the Bangladesh part of the Sundarbans, down from 440, including 21 cubs, in 2004. The census in 2004 was conducted based on pugmarks. In 1975, a field survey conducted by Bubert Hendrichs found 350 Bengal tigers.

In 1982, Margaret Salter carried out a sample and field survey and estimated that the number of tigers was 425. Rex Gittins conducted a survey in 1984 covering 110 sq km area of the Sundarbans South Wildlife Sanctuary and found the tiger population to be 430 to 450.