PRIORITIZING SOUTH-AFRICAN ESTUARIES FOR CONSERVATION - A PRACTICAL EXAMPLE USING WATERBIRDS

This study uses estuarine waterbirds to examine alternative methods fo r prioritizing sites for conservation. South African estuaries are eva luated using single-criterion and multiple-criteria scoring indices an d an iterative technique. The viability of alternative scoring indices for more qualitative data is examined. Species richness, conservation status, total numbers, and percentage of the regional population were considered to be the most important criteria for ranking wetlands in terms of their value to waterbirds. Indices of abundance and site ende mism provide an adequate substitute for the last two criteria when bio ta are difficult to quantify. Sites should be evaluated separately acc ording to single-criterion indices, thereby making the decision proces s explicit. Biogeographical zones should be considered separately when scoring techniques alone are used to select priority sites for conser vation. It is imperative that iterative ('complementarity') analyses, which select the minimum set of sites in which all species can be cons erved, take abundance into account, so that viable populations are con served as far as possible. This selection procedure is flexible, and s hould be used in conjunction with a scoring-and-ranking procedure. Sev en of the 10 estuaries selected by camplementarity analysis to conserv e waterbirds in South Africa were top ranking sites. Two sites (one hi gh ranking) were selected a posteriori to replace three law ranking si tes selected by the program.