Habitat Dynamics of the Greater One-Horned Rhinoceros in the Changing Karnali Floodplain of Bardiya National Park

Floodplains are dynamic ecological systems critical for the conservation of megafauna, including the Greater One-horned Rhinoceros (Rhinoceros unicornis). In Nepal, Bardiya National Park (BNP) provides key habitat for this species, particularly along the Karnali River floodplain, where rhinos were reintroduced from Chitwan in 1986. However, natural hydrological changes have influenced habitat dynamics in this region, most notably the 2009 channel shift of the Karnali River. This study examined Land Use and Land Cover (LULC) changes between 1990 and 2024 and habitat suitability between 2008 and 2024 using multi-temporal Landsat imagery, bioclimatic and topographic variables, and MaxEnt modeling. Likewise, the impact of the hydrological changes, following habitat change, on the rhino population was also studied. LULC analysis revealed increases in forest and grassland cover, alongside a significant reduction in water bodies and agricultural land. Habitat suitability modeling showed a 7.82% decline in suitable habitat, from 4,101.21 ha in 2008 to 3,780.27 ha in 2024. Key predictors included precipitation seasonality (Bio15), Distance to water, and Normalized Difference Vegetation Index (NDVI). Despite vegetation expansion, reductions in water availability, and possible grassland fragmentation, these factors may have degraded habitat quality. The population of the rhino after the hydrological changes did not show a significant increase, suggesting the negative impact of the habitat change on the population. These findings highlight the need for integrated floodplain management to sustain the mosaic of wetland-grassland essential for increasing the rhino population in the western Terai region.