The state of lemur conservation in south-eastern Madagascar: population and habitat assessments for diurnal and cathemeral lemurs using surveys, satellite imagery and GIS

The unique primates of south-eastern Madagascar face threats from growing human populations. The country's extant primates already represent only a subset of the taxonomic and ecological diversity existing a few thousand years ago. To prevent further losses remaining taxa must be subjected to effective monitoring programmes that directly inform conservation efforts. We offer a necessary first step: revision of geographic ranges and quantification of habitat area and population size for diurnal and cathemeral (active during both day and night) lemurs. Recent satellite images are used to develop a forest cover geographical information system, and censuses are used to establish range boundaries and develop estimates of population density and size. These assessments are used to identify regions and taxa at risk, and will be a useful baseline for future monitoring of habitat and populations. Precise estimates are impossible for patchily-distributed taxa (especially Hapalemur aureus, H. simus and Varecia variegata variegata); these taxa require more sophisticated modelling.