Seasonal variations in food plant preferences of reintroduced Rhinos Rhinoceros unicornis (Mammalia: Perrissodactyla: Rhinocerotidae) in Manas National Park, Assam, India

Abstract

The food preferences of translocated Rhinos in Manas National Park were studied to find out variations in seasonal and annual preferences. A total of 139 plants species belonging to 39 families were observed to be consumed as food. On an average, grasses (n = 33) contributed 24% of Rhino food, aquatic plants (n = 23) 16.5%, shrubs (n = 11) 7.5%, herbs (n = 31) 22.3% trees (n = 26) 18.7%, creepers (n = 3) 2.1% and agricultural crops (n = 12) 8.6%. Among the grasses, throughout the year Arundo donax, Cynodon dactylon, Imperata cylindrica, Saccharum elephantinus and Saccharum spontaneum were the maximum preferred species. Rhinos were observed to browse shrubs and tree twigs during the winter season and browsing was found to be very limited during the monsoon due to the abundance of young grass. Various anthropogenic pressures such as unregulated grassland burning, cattle grazing, invasions of Bombax ceiba and shrubs like Chromolaena odorata, Leea asiatica and herbs like Ageratum conyzoides have degraded some of the important grasslands. So, a proper grassland management protocol including the burning of grasslands during the dry season, keeping grazing animals away and control of weeds is suggested in the areas extensively used by the Rhinos.