During the last two decades there has been a regular phenomenon of elephant herds migrating into new habitats and therefore it has become an important issue for managing the population of wild elephants in India. Since 1987, a group of 40-60 elephants has been migrating from Dalma Wildlife Sanctuary of Jharkhand state to vast areas of South West Bengal's forests each year during August-September, and remaining there for 6-7 months.