India: Changes in mangroves may be behind falling tiger count

Prithvijit Mitra The Times of India 13 Oct 11;

KOLKATA: Tigers in the Sunderbans face a new threat, this time from within. An alteration in the composition of the mangrove forest has made it difficult for tigers to hunt and could be a reason behind their dwindling number, says an ongoing study by the School of Oceanagraphic Studies, Jadavpur University.

A sudden proliferation of Baine (avicennia) a" a mangrove variety which is a rich source of food and fodder but has a very high pneumatophore density a" has taken researchers by surprise. Further rise in its number could be disastrous for the big cats in Sunderbans, the study says. Baine has two sub-species a" avicennia marina and avicennia alba.

Till the late Eighties, Baine comprised less than 1% of all mangroves in the forest. It now accounts for around 10% which is alarming, said the experts. Its pneumatophores can spread across a radius of up to 20 feet and make movement extremely difficult for tigers. In the slippery and dense terrain where hunting has never been easy for tigers, Baine has been making it even tougher.

asBaine has the highest pneumatophore density among mangroves. As it is, tigers get little room to run and catch a pray in the Sunderbans. They have to rely on short bursts to make a kill, catching their pray by surprise. More Baine means even that has now become difficult in certain areas,a? said Pranabesh Sanyal, a member of the research team.

Sunderbans has 94 species of mangroves. Goran (ceriops) and Gewa (excoeceria egallocha) comprise nearly 70% of the mangroves. Baineas proliferation can be directly linked to a rise in salinity, said the study. "Among all the mangrove varieties, it can withstand salinity the most. Our study also shows a sharp rise in salinity a" both in rivers and in ground water. The more the salinity, the more conducive it will be for Baine," added Sanyal.

There was, however, a flipside to it. Being rich in food value and a good fodder, the mangrove variety could actually be a boon for the residents of Sunderbans. Used as cattle fodder, Baine leaves and twigs were better than straw, the study said. Its leaves are widely used as vegetables in Gujarat and Sunderbans could follow suit. "A toxicity test is now being done to assess its suitability for human consumption. If it passes the test, this mangrove could be a cheap and easy source of food for locals. The latter could also save money by using it as fodder," said Sanyal.

Baine could be planted in the creeks along villages, it has been suggested. Since these areas donat have a tiger population, it wonat affect them. But since it has been growing deep inside the forests, it has been largely inaccessible to the local population. "No solution is in sight, for you canat chop them off. That would be detrimental to the eco-system. We must wait for some more time and observe the consequences," Sanyal said.

Some experts, however, felt it was still too early to conclude that Baine has been affecting tigers."First, there has been no study to assess the impact of Baine on tigers. Secondly, tigers are remarkably adaptable creatures who can adjust to adverse conditions. The fact that they have survived in the Sunderbans is ample proof of that. But if Baine has indeed been proliferating then we need a proper study. It should be taken seriously," said Shilanjan Bhattacharya, member of the State Wildlife Advisory Board.