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.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/utilization-food-plants-migratory-elephants-wilderness-south-west-bengal
[2] http://admin.indiaenvironmentportal.org.in/category/author/k-santra
[3] http://admin.indiaenvironmentportal.org.in/category/author/s-pan
[4] http://admin.indiaenvironmentportal.org.in/category/author/k-samanta-et-al
[5] http://admin.indiaenvironmentportal.org.in/category/journal/tiger-paper
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/elephant
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/migratory-species
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/west-bengal