The role of size and number of forest patches in the conservation of bird species in a fragmented landscape

Abstract

We used presence data to evaluate the role of small patches in bird conservation in the Cape Coast Metropolis of Ghana by surveying 24 forest patches. Cumulative species-area and number curves were plotted by ordering patch size from large to small and then small to large and values for cumulative area or number, richness and abundance calculated. We identified a total of 162 bird species during the study. There was no relationship between either patch area or number of patches and either species richness or abundance of birds. Therefore, we could not support the theory of passive sampling, which suggests large patches host higher species richness than small patches. Perhaps, this is, because of the following observed phenomena: 1). Edge effect, as species from nearby matrices used the patches; 2). Habitat sampling, as species sampled several different patches; and 3). Spillover, as species moved from nearby large reserves, such as Kakum Conservation Area (KCA), to the patches. The patches together occupied 2 947 ha and, compared with KCA, this is a ratio of 1:12, but the ratio in terms of species richness is 2:3, suggesting that many small patches could host more species than one large patch of comparable size. Thus, small patches are valuable for the conservation of bird species, which calls for various conservation bodies and institutions to take measures towards protecting such patches.