Seasonality and Diversity of Four Monkey Species within Okomu National Park, Nigeria

Abstract

Primates play a critical role in maintaining tropical forest ecosystems, yet their populations are increasingly threatened by habitat disturbance and hunting pressures. The objective of this paper to assess the species occurrence, seasonal variation, and diversity of four species of monkeys in Okomu National Park, Edo State, Nigeria using appropriate standard methods. A total of 1,391 individuals belonging to four species (Cercopithecus mona, Cercocebus torquatus, Cercopithecus erythrogaster, and Cercopithecus nictitans) were recorded. C. mona was the most abundant species overall (41.29%), followed by C. erythrogaster (27.12%), while C. nictitans was least represented (12.73%). Seasonal variation showed that C. mona and C. erythrogaster dominated in the wet season (46.68% and 26.74%, respectively), whereas C. torquatus increased in prominence during the dry season (22.63%). Diversity indices revealed C. erythrogaster as the richest and most diverse species, with strong representation across adult and juvenile stages, while C. torquatus displayed higher calf diversity. These findings show the ecological importance of C. erythrogaster as a conservation priority and underscore the vulnerability of C. nictitans to population decline.