Preliminary Study of the Population Density of Mona Monkeys (Cercopithecus mona) in Omo Forest Reserve

Abstract

In the last 40 years, threats to the survival of wild primate population have greatly increased. Globally, primate population is severely threatened with extinction especially due to habitat loss from conversion of forest areas to farmland and/or unsustainable logging. There is paucity of information on the population density and abundance of Mona monkeys in Omo Forest Reserve. The population density and distribution of Mona monkeys were conducted in two forest blocks of Omo Forest Reserve (OFR). The objective of the study therefore, is to determine the population density and distribution of Mona monkey, and ascertain the presence of other primate species in sympatric relationship with the monkey. The line transect sampling method was used for the enumeration. Data were collected from seven (7) transects randomly selected from two forest blocks; the Elephant Sanctuary (4) and the Strict Nature Reserve (3). Other primate species were considered to be sympatric with Mona monkeys if they were encountered within 20 m proximity range with the target species. Data on threat of human activities were collected in Omo Forest Reserve based on four major categories (Hunting/Poaching, Logging, Farming, and Collection of Non-Timber Forest Products). Analysis was carried out using IBM SPSS Statistics 20 to determine population density estimate and the relative density in the two forest blocks. The field work took 30 days each, in September, 2015 and March 2016 that covered both seasons. Results revealed that a total number of 57 Mona monkeys with density of 0.44 km−2 in the entire reserve were sighted during the survey. The relative density across the two forest blocks surveyed in the forest reserve revealed that Mona monkeys were present in both the Elephant Sanctuary (ES) (n = 42) and Strict Nature Reserve (SNR) (n = 15) with density of 0.27 km−2 and 0.18 km−2, respectively. The species were observed to be more active during morning surveys than in the evening surveys, with densities of 0.77 km−2 and 0.4 km−2 recorded, respectively. The mean encounter rates for the species were 3.31 km−1 and 1.5 km−1 for morning and evening surveys, respectively.