Trap cameras placed inside the Sunderbans to estimate the number and assess the habitat of tigers have suggested a change in the behaviour of another apex predator in the mangroves.
The images show crocodiles are nesting in seemingly new areas deep inside the forest, said forest officials.
Crocodiles usually lay eggs near the riverbank or creeks. During the crocodile estimation exercise in 2024 and 2025, forest personnel did not find enough nesting sites near the water bodies.
“We were searching for the nests but we found only one or two nests close to the rivers and creeks. We were surprised about not being able to find enough nests near the creeks,” said Rajendra Jakhar, field director of the Sundarban Tiger Reserve (STR).
“The images captured by the trap cameras show that crocodiles are venturing deeper into the forest than we thought. They are nesting inside the forest.
The cameras are placed on slightly higher grounds to prevent inundation during high tide,” he said.
In 2024, the crocodile estimation was done in the Sunderbans after 12 years. This year, it was done again.
“Regading habitat utilisation, there are some other factors that emerged. Our crocodile number was lesser than Bhitarkanika (in Odisha). But our forest habitat is much better from the point of view of biodiversity.The disturbance or biotic interference is not much. So we were puzzled why enough nesting was not happening. We now know that one reason might be that the crocodiles are nesting deeper inside the forests,” said a forest official.
“The danger is that the eggs are exposed to other predators. But at the same time, it saves the eggs from getting damaged in tidal waters. I think the crocodiles are adapting,” he said.
More than 1,400 cameras were placed at strategic locations across the STR and South 24-Parganas forest division from November 20, 2024, to January 6 this year.
In the 45-odd days, the cameras clicked around 2.5 lakh raw pictures that are now being analysed, said a forest official at Aranya Bhavan, the state forest department headquarters.
Apart from tigers and crocodiles, the cameras clicked pictures of several other mammals. The images are a pointer to the rich biodiversity of the mangrove delta, said forest officials.
Three types of small cats — fishing cat, leopard cat and jungle cat — have been clicked in good numbers, said Jakhar.
The pictures also suggest a thriving population of otters, he said.
The Sunderbans is home to two otter species: the smooth-coated otter and the Asian small-clawed otter, both classified as vulnerable by IUCN. The reserve’s creeks and channels provide a viable habitat for them.
Wild boars and spotted deer, the main prey base of the tiger, are also present in good numbers, he said.
The annual exercise is conducted by the forest departments of the states that have tigers in the wild. The national tiger census, a quadrennial exercise, is conducted by the National Tiger Conservation Authority, which functions under the Union government.