Ecological Assessment of a Shifting Conservation Landscape in Kenya

Abstract

The Aberdare Conservation Area (ACA), located in the central Kenyan highlands, is one of Africa’s flagship National Parks. The area harbors large amounts of African wildlife including several species of afromontane endemics that are of conservation concern. Since its inception, the ACA has experienced explosive human population growth at its margins, with associated domestication of the surrounding landscapes. Both processes have led to a de facto isolation of the ACA from other natural areas. Even before the establishment of the national park, local authorities started collecting systematic wildlife records. These nightly surveys, conducted by trained professionals using standardized protocols over a period of approx. 50 years, provide a unique opportunity to evaluate the effects of various conservation measures including the construction of a perimeter fence. Here I analyze two exceptionally long-term nightly datasets on the diverse mammal community (46 spp.) collected in two different locations, one close to the edge of the protected area (Treetops Lodge) and one closer to the core of the park (The Ark Lodge). I found not only clear difference in the two species communities, but also differentiation in the temporal changes of wildlife populations between the two sites. Five taxa (bushy-tailed mongoose, coypu, reedbuck, impala, and eland) appeared in the resident mammal community during this study, while eight species (aardvark, bushpig, bongo, civet, Harvey’s duiker, jackal, lion, and zorilla) disappeared. The species that have disappeared from the ACA are either intrinsically rare taxa or savanna species that have had a marginal existence within the limits of the ACA. I find strong evidence for edge effects with the site closest to the border of the ACA (Treetops); this site registered the strongest losses in total wildlife population numbers, aggregate wildlife biomass, species richness, and compound indices of species diversity. Establishment of a fence around the

area starting in 1989 led to temporary increases in wildlife populations near the park margins, but in the last 10 years these gains have been reversed and wildlife populations have continued to decline near the edge of the park. In contrast, wildlife populations near the core areas (The Ark) appear to have remained relatively stable over the years.