The northern river terrapin (Batagur baska ) is a species of riverine turtle native to Southeast Asia. It is classified Critically Endangered by the IUCN and considered extinct in much of its former range.
The Northern river terrapin is a rare freshwater turtle native to Southeast Asia. It is one of Asia's largest freshwater and breakwater turtles. The upper surface of its carapace and the soft parts are generally olive-brown, while the plastron is yellowish. Head and neck are brown with reddish bases. Males in breeding coloration have a black head and neck with a crimson or orange dorsal surface and red or orange forelegs. The color of the pupils also changes during this period, to brown in females and yellow-white in males.
Northern river terrapins are currently found in Bangladesh, India, and Myanmar. They are strongly aquatic but use terrestrial nesting sites, frequenting the tidal areas of estuaries, large rivers, and mangrove forests.
Northern river terrapins spend most of their time in water and only come on land to lay eggs. They are even known to undertake long seasonal migrations of 50 to 60 miles (80.5-96.5 kilometers) to the sand banks where they were hatched. Northern river terrapins are social creatures and are often seen basking together during the day. At night they rest in their burrows in the mud at low tide.
Northern river terrapins have an omnivorous diet, taking waterside plants and small animals such as clams.
The breeding season of Northern river terrapins takes place between December and March. Females usually lay three clutches of 10-34 eggs each; communal clutches of several females in one nest are not uncommon. The eggs typically hatch in 70-80 days, depending on the temperature and the depth of the nest.
The Northern river terrapin is considered extinct in much of its former range, principally due to exploitation as a food item (including egg harvesting). Previously, immense numbers were shipped into the fish markets of Calcutta from throughout India; among the Bengali Hindus, the river terrapin was considered the most delectable of all turtles. It is still illegally exported from Indonesia and traded in large numbers in China. Loss of nesting beaches and pollution are also impacting the species.
According to the IUCN Red List, the total population size of the Northern river terrapin is fewer than 100 mature individuals. Currently, this species is classified as Critically Endangered (CR) on the IUCN Red List and its numbers today are decreasing.