Avifaunal biodiversity in peril: pre- and post-vegetation clearance survey of avifauna in a fragmented thicket in an urban landscape, Dar es Salaam City, Tanzania
In contrast to the bird faunas of most protected areas in Tanzania, those found in urban areas have poorly been studied. In December 2009 and May 2010, using mist netting and audiovisual observations, we undertook surveys of birds at Kituo cha Biomazingira Dar es Salaam (KIBIDA), a privately owned 6 ha area, as an initial attempt to ascertain which bird species are found there. In 2012 and 2017 this 6 ha area (dominated by thickets) was cleared by unknown people further reducing it to about one-third and one-sixth of the original area, respectively. This led us to further assess whether the birds were negatively affected by habitat reduction after one-third and one-sixth of the study area remained. In both cases we continued to use mist nets augmented by audio-visual observations of birds. We detected a total of 98 species of which 62, 48, 53 and 42 were recorded before wood vegetation in the original 6 ha area was cleared, during clearing, two years and six years after it was cleared, respectively. Some of the species detected were forest-dependent and Palaearctic migrants suggesting that remnant thickets and forest patches in urban landscapes are important for conservation of forest dependent and migrant birds. Twenty-two species that were detected before the wood vegetation in the area was cleared were neither found during the time of clearance nor after clearance suggesting possible emigration or local extinction. Similarly, 44 species that were not found in the study area prior to clearance were either observed or mist netted afterwards as a result of turnover in species composition during the sampling period. The results suggest that there is a need to continue to protect KIBIDA and other similar habitats in urban landscapes in order to preserve their avifauna. The results further imply that should such habitats continue to be cleared for provision of settlement, some of the bird species found in them will be lost leading to local extinction. As such, the study recommends conserving thickets and forest patches in urban landscapes as habitats for birds and other fauna.
Keywords: remnant thicket, habitat reduction, urbanization, avifauna, mist netting, Dar es Salaam