Population trends of antelopes in Waza National Park (Cameroon) from 1960 to 2001: the interacting effects of rainfall, flooding and human interventions

摘要

Antelopes are prominent wildlife in Waza National Park, situated in Sahelo-Sudanian Cameroon, which has witnessed dramatic changes in rainfall and flooding. To assess their impacts, we reviewed 26 aerial and terrestrial surveys, comprising total, transect and localized counts. Estimated numbers of kob using the floodplain throughout the dry season, dropped from 20,000 in the 1960s and 1970s to 2000 in the mid-1980s. They recovered to 5000 in the mid-1990s but not further despite increased flooding. Estimated numbers of korrigum and roan using the floodplain later in the dry season, dropped in the early 1970s and only slightly recovered in the 1990s. The diversity of counting methods notwithstanding, the drop in kob numbers and the disappearance of waterbuck can be attributed to the construction of the Maga dam upstream in 1979 and subsequent low rainfall. The kob population structure suggests that its reproduction capacity was, however, not hit. Antelope-livestock contacts, provoking the transmission of diseases such rinderpest during droughts, explain better the dramatic drops in population numbers than poaching, which is likely to have remained rather constant. The effects of rainfall, flooding and human interventions on antelope populations increasingly appear to be interacting.