Development of an early warning index to predict the fragmentation of bird distributions
Abstract
Birds are precious bio-indicator of ecosystems health. Studying their distribution throughout time would help anticipate biodiversity erosion. This study relies on the data collected in order to create the Second Southern Bird Atlas Project (SABAP2). The latter is an initiative that aims to learn about bird distributions and also to raise awareness about biodiversity and particularly about avifauna. The dataset is substantial and allows statistical analysis. Three different methods are developed to measure the fragmentation of bird distribution. Two of them appear to give similar results: The Pearson's product-moment correlation coefficient and the Moran's I. The data collection has been done by volunteers, therefore the protocol cannot be entirely standardized. It follows that shortcomings exist and that they must be taken into account. This is only partially done in the two selected methods which gives them different advantages and limits. The Moran's I method can probably be improved to get a more comprehensive approach. The newly created index gives an information regarding the level of fragmentation, it does not directly say whether or not the species is in difficulty. Indeed, we expect different levels of fragmentation between specialist and generalist species. The results regarding Southern African species surprisingly shows that habitat non specialist species have some of the roughest distribution. Moreover, being most of the time abundant and common species, the data collection is fairly correct.