Tigers in the Sundarbans increase by 11, now 125 in total

The number of tigers in the country has increased by 11 over the past six years. The forest department found this figure by conducting a survey in the Sundarbans, the only habitation of tigers in the country. The number of tigers increased the most in Khulna district.

Meanwhile, there has been a decline in that number in the Satkhira portion of the forest. People involved with the study believe that the number of tigers decreased in that area due to poachers and the decline in tiger prey (deer).

The forest department officially released the actual number of tigers and a report on this matter Tuesday. The survey was conducted in the Sundarbans during January, April and November of last year and in March this year.  

That survey was conducted on a 2,240 square kilometres area of the Sundarbans. A total of 657 cameras were installed there. Whenever tigers passed by those cameras, they automatically took photographs of the tigers. Out of the total 31,482 photographs taken by those cameras, there were 7,297 photographs of tigers.

Other than the cameras, a spot survey was carried out on 1,306 kilometres of area on the banks of canals in the Sundarbans. The exact number and population density of the tigers were determined by counting the pug marks of tigers in these canals.

On average, the existence of 2.62 tigers has been found in the survey within every 100 square kilometres of area. Photographs of a total of 84 tigers were captured on cameras. The remaining 41 tigers were found by surveying the canals.

When asked about the results of the tiger survey, chief conservator of forests Amir Hossain Chowdhury told Prothom Alo, “The number of tigers has increased in the Sundarbans of Bangladesh. We are working on increasing that number even more. And we believe that’s possible with the help of all.”

However, an imbalance has been noticed in the ratio of the numbers of male and female tigers this time in Khulna part of the Sundarbans.

There were 21 females and 62 males among the 84 tigers spotted in the camera survey. And, the gender of one tiger could not be determined. Wildlife experts believe this ratio of male and female tigers to be accurate on the whole.

Meanwhile, the imbalance between the ratio of male and female tigers in Khulna range that has been found during the survey is that 12 female tigers have been found against only one male tiger in that area. That means, if that one male tiger is dead there looms a risk of the whole area being left without a male tiger.

As a result, the number of tigers in that area could decline fast in the long term. The report put emphasis on the issue of increasing the number of tigers in that area under such circumstances.

Meanwhile, the report mentioned the role of poachers as the reason behind the decline in the number of tigers in Satkhira range.

It has been found in various studies that a major portion of those poachers smuggle out tiger cubs and organs to different countries around the world. Experts believe these cubs and organs are smuggled off to the East Asian countries including China and Thailand via India and Tibet.

However, another positive aspect regarding the number of tigers in the country has also come up in that survey. The number of tiger cubs was found to be five in the previous two surveys done in 2018 and 2015. This time the number of cubs has risen to 21 and this figure indicates that the number of tigers would increase even further in future.

According to the forest department, cameras were installed on trees 50 centimetres above the ground for the tiger survey in the Sundarbans. Whenever a tiger or another animal moves past the cameras they automatically capture photos and 10-seconds videos of them.

Then the number of tigers is determined by analysing the photographs collected through camera trapping at the resource information management system unit of the forest department. Besides, all the tigers usually come to the canals in the Sundarbans to drink water.

The tigers leave their pug marks on the banks of the canals from doing so. And, those pug marks are different based on the categories of the tigers. The number of tigers can also be counted from observing the pug marks like this.

In response to the question how the same-looking stripped tigers of the same colour living in the vast area of the Sundarbans are identified separately, director of the tiger conservation project Abu Naser Mohsin Hossain said, just as the fingerprints of one person don’t match those of another, the stripes of one tigers are also unique from that of others.

The cameras can capture hundreds of photographs of the same tiger. Exactly how many tigers are there in the Sundarbans can only be determined after collecting those photographs and analysing the data of each tiger separately on the computer software, he added.

According to sources at the forest department, the number of tigers found in the Sundarbans during the survey done in 2004 was 440. Earlier, the number of tigers mentioned in the survey conducted in 1996-97 was 350 to 400. In those two surveys, the number of tigers was determined from counting the pug marks. However, questions were raised from different quarters about the credibility of that method.

The survey from 2015 was the most modern and scientific one. That survey had found a total 106 tigers in the Bangladesh part of the Sundarbans.

Considering that figure reliable, steps were taken to increase the number of tigers later. In the previous survey of tigers in 2018, the number of tigers in the Sundarbans increased from 106 to 118.

* The report, originally published in the print and online editions of Prothom Alo, has been rewritten in English by Nourin Ahmed Monisha