ABUNDANCE AND SPECIES RICHNESS OF SMALL TO MEDIUM-SIZED MAMMALS ALONG A GRADIENT OF HUMAN DISTURBANCE AT MAU FOREST COMPLEX, KENYA

Abstract

Anthropogenic influence on biodiversity results from the burgeoning human population and the associated human agricultural and infrastructural needs. The Mau Forest Complex (MFC) is a biodiversity hotspot, however, species are predicted to be declining at unprecedented rates due to the loss of habitats. Using camera traps, this study investigated the abundance and species richness of non-volant small to medium-sized mammals (including small carnivores) along a gradient of human disturbance of three treatments (adjacent farmlands – AFs, secondary forest – SFs, and primary forest – PFs) at the Transmara and Maasai Mau forest blocks of the MFC. Mammals were recorded at 181 camera-trap locations from 246 camera deployments and 5,509 sampling days. From 302,997 images, 47,345 were of wildlife species. A total of 53 species belonging to 8 mammal orders were recorded, with 20 species belonging to the order Carnivora representing seven families. Additionally, 15 species of the order Artiodactyla, 1 species of Lagomorpha, 1 species of Hyracoidea, 1 species of Proboscidea, 9 species of Rodentia, 7 species of Primates and 1 species of Tubulidentata were recorded. While Alpha diversity, as measured by Shannon’s entropy, was not significantly different between Transmara and Maasai Mau forest blocks (P > 0.05), it differed significantly among treatments, with AFs showing lower diversity than both PFs and SFs, and the former having significantly higher diversity than the latter at both forest blocks. Beta diversity differed significantly between primary and secondary forests (df = 1, P< 0.05), primary forests and adjacent farmlands, and adjacent farmlands and secondary forests, and this trend was the same for the two forest blocks. In terms of occupancy of small carnivores, overall occupancy (mean ψ) was highest in PFs and least in AFs. At the individual species level, Jackson’s mongoose (Bdeogale jacksoni), a known forest specialist, had the highest occupancy in PFs and the least in AFs. Detection rates for various functional groups were similar across treatments for Afrotherians, Carnivora, and small rodents but differed significantly for large rodents, primates, and ungulates. This study demonstrates the adverse negative influence of anthropogenic disturbance on the persistence of a range of small to medium-sized mammalian communities at the Mau Forest Complex, with different species and functional groups responding differently to human land-use practices. Particularly important is that the less-disturbed primary forests supported more habitat specialists or forest-dependent mammals and should be preserved to support overall and forest specialist species richness.