Contrasting amphibian population trend from a protected area in Madagascar reveal severe underestimation of extinction risks

Abstract

The amphibian endemic fauna from Madagascar is currently facing multiple threats, including habitat loss, climate change and invasive species. Many species are listed as threatened by the IUCN, but long-term monitoring is scarce and assessments rarely account for population trends. Using a 13-year amphibian survey in the Strict Nature Reserve of Betampona (eastern Madagascar), we assessed the population trends of 38 species between 2010 and 2022 based on amphibian activity. Despite the high protecction status of the reserve, we found a negative trend for 15 species, a positive trend for 13 species increasing and 13 species with no significant trend detected. We propose to update the status of 15 species towards a threatened category (CR, EN, VU). Contrasting population trends in amphibians from Betampona might modify species composition and ecosystem functions in the future. This study highlights an important underestimation of extinction risks for a large proportion of amphibians from Madagascar, and more generally in the tropics where long-term population trends are poorly documented.