Distribution and conservation of the coastal population of the black-headed dwarf chameleon Bradypodion melanocephalum in KwaZulu-Natal

Abstract

The coastal population of the black-headed dwarf chameleon Bradypodion melanocephalum in KwaZulu-Natal appears to be centred on the eThekwini Municipal Area, which is experiencing rapid urban development. This population occurs in few statutory protected areas, all of which are small. In order to conserve successfully the coastal population in KwaZulu-Natal, knowledge of its geographic range and location of potentially suitable habitat is required. Bradypodion melanocephalum was until recently known mainly from Durban, with isolated records from areas to the north and south. A cartographic model was used to estimate the distribution of the coastal population in KwaZulu-Natal. The model predictions were ground-truthed, and the model was found to have a positive predictive power of 0.57 and a negative predictive power of 0.84. The relatively low positive predictive power of the model appeared related to habitat management that is not appropriate for the conservation of B. melanocephalum. The geographic range was then estimated using a Maxent model to predict climate suitability while at the same time taking cognizance of a dispersal barrier, the output of which was further refined in a geographic information system to exclude areas of unsuitable landcover. The variables included in the final model were mean daily minimum temperature of the coldest month and mean daily maximum relative humidity of the coldest month. Both these variables relate to dew formation in the dry winter period, and dew appears to be a critical water source for B. melanocephalum during winter. The Maxent model estimates greater probabilities of occurrence towards the coast, where rapid urbanisation is occurring. This urbanisation is one of the threats to the survival of the coastal population of Bradypodion melanocephalum. The utility of translocation of B. melanocephalum to areas that will not be developed within a development site in comparison to translocation ofT-site as mitigation to ensure the conservation of the coastal population in rapidly urbanizing areas needs to be investigated further.