Population Estimate and Threats to Hippopotamus (Hippopotamus amphibius) in the Benue River, Benue State

This study estimates the population of Hippopotamus amphibius in the Nigerian stretch of the Benue River through Benue State, located in Nigeria's North Central geopolitical zone, and documents the primary threats facing the population. Hippopotamus is considered vulnerable on the IUCN Red List, and its population in the Benue River has declined substantially from historical numbers, yet recent quantitative data are lacking. Population estimates were derived from repeated diurnal and nocturnal boat surveys using distance sampling methodology along 220 km of river channel. Individual animals were counted, group sizes recorded, and locations GPS-tagged. Local fishers and farmers were interviewed regarding conflict incidents and hunting activity. A total population estimate of 68 to 94 individuals was obtained from detection functions, far below historical reports of several hundred animals. Groups were concentrated in three core areas associated with suitable sandbank and shallow riparian habitat. Human-wildlife conflict was documented at 14 locations, with crop raiding and boat capsizing as the most frequent incidents. Evidence of recent hunting was found at two locations. River dredging and sand excavation activities were identified as critical emerging threats. The study recommends declaration of the three core hippo concentration zones as community-managed conservation areas, legally binding restrictions on riverbed excavation, and compensation schemes for conflict-affected farming communities. Keywords: hippopotamus, population estimate, Benue River, human-wildlife conflict, conservation.