Population dynamics of the mona monkey, Cercopithecus mona (Schreber, 1774) and anthropogenic threats in selected areas of Lagos State, Nigeria

Abstract

The mona monkey (Cercopithecus mona) is the major non-human primate adapted to swamp forests that characterizes Lagos State. It is useful in ecological services as seed disperser and reforestation. Efforts to legally conserve this species have been ineffective due to non-enforcement of conservation laws. This study determined the population estimate and threats to C. mona in order to provide useful information for its conservation in Lagos State. Using total head count and questionnaires, the occurrence, abundance, population composition, and the anthropogenic threats to the C. mona in three Local Government Areas (LGAs) viz: Eti-Osa, Ibeju-Lekki and Kosofe were determined. Population surveys were conducted during the wet and dry seasons from September, 2021 to April, 2022. Data were collected through field surveys and administration of questionnaires. The data were analysed descriptively and inferentially. Significant differences were at p<0.05. Mona monkeys were sighted in all the three LGAs. The estimated population was 466 individuals. The highest wet and dry season’s population of 206 and 196, respectively were recorded in Ibeju-Lekki LGA. The juveniles (185) and adult females (104) were the most abundant in the three LGAs. There was a significant difference (Chi-square = 16.18, p< 0.05) in the population of infants in Ibeju-Lekki and Kosofe LGAs. A decline in C. mona population was indicated by 54.4% of the respondents, while 50.8% showed that high rate of urbanization was a major threat to the monkeys. Most respondents (74.7%) indicated that decline in forest cover over the years was affecting the monkeys’ population. The need for conservation of C. mona is critical in Lagos State. This could be achieved through the effective enforcement of existing conservation laws and promulgation of new efficient ones.

Diet of the mona monkey Cercopithecus mona in the Gnanhouizounmè community forest in Southern Benin

“…The mona monkeys' diet in the dry and wet seasons is mainly made up of fruits (mature and immature), followed by seeds. This finding supports previous studies about the frugivorious diet of the species (Matsuda Goodwin 2007, Ejidike andSalawu 2009;Olaleru et al 2020). Fruits provide mainly carbohydrates and energy to primates (Riba-Hernandez et al 2003).…”

“…The mona monkey consumed parts of 22 plant species during both dry and wet seasons. The species richness found in this study was lower than the 31 species reported by Olaleru et al (2020) in Okomu National Park, Nigeria. Some species, such as Pycnanthus angolensis, Raphia hookeri, Xylopia aethiopica, etc.…”

“…This observation suggests that their feeding activity occurs mainly during these periods. Similar observations were reported by Olaleru et al (2020). This pattern could be due to the fact that the species is more active during the morning (Uloko and Lameed 2019).…”

“…At times, the species was also seen eating insects. However, we did not count or identify these because they were difficult to identify with the methods used due to their small size and the fact that they did not fall out of the monkeys' hands (Olaleru 2016). Insects are a source of proteins to complete those supplied by plants.…”

“…The mona monkey is a social animal that lives in groups of up to thirty-two individuals (Glenn 1997). It is a forest species, although it can adapt to degraded habitats (Olaleru 2016). The species was formerly classified as Least Concern status on the IUCN Red List, but is currently classified as Near Threatened as it is confronted with anthropogenic threats such as habitat degradation, hunting, and poaching (Matsuda Goodwin et al 2020).…”