Hog deer Axis porcinus need threatened tallgrass floodplains:: a study of habitat selection in lowland Nepal

In Asia, subtropical tall grasslands and their associated fauna are mostly confined to the floodplains of the large rivers draining the Himalayan range. In recent decades, cultivation and hydroelectric dam construction have severely reduced their spatial abundance. During 1998-2000, we conducted a detailed study of the habitat use of hog deer, Axis porcinus, an important prey species of tiger, Panthera tigris, in the floodplains of the large Karnali river in Royal Bardia National Park, Nepal. Strong preference for tall grass and avoidance of the successional stages following riparian forests throughout the year was revealed by analyses of tracking data from 18 radio-collared deer and from density estimates from block counts (n = 46) in different habitat types. Continuously strong selection for tall grass despite the reduced availability of this habitat type during the monsoonal flooding indicated an insignificant effect of density-dependent factors in habitat selection. Reduced availability of cover following traditional cutting and burning of the tall grasslands by local villagers did not produce changes in habitat use or an increase in daily movements, indicating an absence of trade-offs between habitat preference for food and for predator avoidance. By regulating fluvial action, hydroelectric power development will lead to the loss of tall grasslands due to accelerated secondary succession, which will therefore adversely affect the viability of local populations.