International Tiger Day: A sustainable way to increase tigers in Sundarbans
At the last count, there were 114 tigers in 2018 as per the Bangladesh Forest Department—an increase of eight since the 2015 tiger survey. In India, however, there were 97 tigers in 2019, up from eight in 2017. The Sundarbans, the world's largest mangrove forest comprising 10,000 square kilometres of Bangladesh and India, is the only place in the world where Royal Bengal tigers can be found.
In comparison to Bangladesh, the Indian Forest Department has been working hard for a long time to enhance the tiger population in the Indian Sundarbans. Accordingly, its tiger population is growing faster than that in Bangladesh. Indigenous peoples that lived in the Indian Sundarbans have been relocated and CCTV cameras are being installed and public mobility is monitored and restricted at tiger sanctuaries. On the other hand, just a few years ago, shootings and abductions of bandits and law enforcers in the depths of the Sundarbans were an everyday occurrence in Bangladesh (this has now largely declined). Still, the movement of people in Bangladesh's Sundarbans is much greater than in the Indian part. People are free to enter the forest for honey, golpata, fish, forest timber, and firewood. As a result, tigers are becoming insecure in their habitat and conflict between tigers and humans is also on the rise.
To control public mobility in the Sundarbans, CCTV cameras should be placed in strategic locations and forest-dwellers should be rehabilitated outside the forest. Fish farming, cattle rearing, renewable fuels, and artificial honey farming projects and other operations can help to minimise the number of people who rely on the forest. It is possible to also reduce tigers' presence in areas where people live by installing solar panels between the forest and the locality. Bushes in the forest are diminishing due to illegal timber collection, making it more difficult for tigers—who prey mainly on small mammals and deer—to hunt. In addition, the water level and salinity are rising due to unnatural cyclones, storms, and tidal surges. Natural reservoirs need to be created to address this.
Besides the measures stated above, the reintroduction process may protect and increase the tiger population in the Sundarbans. The number of tigers has not grown as expected—if there were 20 adult female tigers out of 114 tigers, they should have raised at least 20-40 tiger cubs per year. But the number of tigers is not increasing that way, which may be due to the lack of genetic diversity in the population. Due to the small number of tigers, there is more likely to be inbreeding—which has the potential to cause morbidity and increase the mortality rate of tiger cubs. Therefore, it is necessary to bring about genetic diversity by increasing heterogeneity; this will help the tiger population by increasing the number of offspring as well as increasing the tigers' immunity and adaptability to different environments.
Reintroduction can be an effective way of increasing genetic diversity. By adopting a long-term project and through the following steps, it is possible to reintroduce a large number of tigers into the wild. First, 10 tigers can be collected from different zoos and safari parks in Bangladesh. The newborn tiger cubs can be raised in a greater area near the Sundarbans after six months of age and trained to hunt. These tiger cubs will then be released into the Sundarbans when they reach adulthood. Next, to avoid conflict with existing tigers, tiger-free regions should be selected for these new tigers. The tigers released into the wild should also be monitored by CCTV cameras. Last, to give them access to food, deer and pigs can also be released at the same site. A separate captive or semi-captive establishment near the forest can be operated for the breeding and rearing of pigs and deer for this purpose.
Management of human and natural factors as well as genetic factors must be taken into consideration in conserving tigers in the Bangladesh Sundarbans. The survival of such a small number of tigers in the face of severe climate change will be very difficult in the future. Therefore, along with other measures, reintroduction work should be started to rapidly increase the number of tigers in the Sundarbans.
Md Shahadat Hossain Shuvo is the Deputy Curator at the Chittagong Zoo.