Researchers found that the number of common hippopotamus in the Bui National Park declined by about 70 percent following the construction of a hydroelectric dam in the reserve. From 209 individuals before the dam construction, the number declined to 64. Land cover changes led to severe reduction in forest cover and destruction of riparian areas through flooding. In addition, poaching activities increased during and after the construction period.Researchers found that the number of common hippopotamus in the Bui National Park declined by about 70 percent following the construction of a hydroelectric dam in the reserve. From 209 individuals before the dam construction, the number declined to 64. Land cover changes led to severe reduction in forest cover and destruction of riparian areas through flooding. In addition, poaching activities increased during and after the construction period.