Seasonal variation, diversity and population dynamics of four species of monkey in Okomu National Park, Edo State, Nigeria

Abstract

The aim of this work is to ascertain the diversity, seasonality and dynamics of four monkey species in Okomu National Park, a lowland rainforest ecosystem of Edo State, Nigeria. It covers a land mass area of approximately 200km square, making it the smallest of the National Parks in Nigeria. Daily surveys of monkeys were carried out between 7:00am and 11:00am while evening surveys were between 03:00pm - 06:00pm for 8 months covering 4 months of wet season and 4 months of dry season. Each trail was traversed twice daily with an average walk speed of 1.0 km/hr. Sightings was aided with binoculars, digital camera and acoustic detection. Results showed that a total of 1391 monkeys were sighted, six hundred and sixty-two (662) in the wet season and seven hundred and twenty-nine (729) in the dry season. The results also show that the percentage abundance is Cercopithecus mona > C. erythrogaster > Cercocebus torquatus > Cercopithecus nictitans. The overall percent composition of the species showed that C. mona had the highest of 48.5%, followed by C. erythrogaster 27.12%, C. torquatus 18.85% and the least was C. nictitans 12.75%. This study confirms the prevalence of four (4) species of Monkey in Okomu National Park which are Cercopithecus mona, Cercopithecus erythrogaster, Cercopithecus nictitans and Cercocebus torquatus. Biological indices indicate that Cercopithecus erythrogaster is the most diverse and the richest species in Okomu while the least diverse species is Cercocebus torquatus. Cercopithecus nictitans is the most evenly distributed monkey species in Okomu National Park. We recommend continuous survey and monitoring of primate species in this area and encourage community-based conservation policies to protect the already threatened primates and habitat.