Population Status and Vulnerability of Mantidactylus pauliani from Ankaratra Protected Area, Madagascar

SIMPLE SUMMARY: Mantidactylus pauliani is a locally endemic amphibian species restricted to mountain streams on the Ankaratra Massif, in the central highlands of Madagascar. This species has a highly restricted distribution, which makes it vulnerable to habitat destruction and, consequently, M. pauliani is considered one of the most threatened frog species in Madagascar. Therefore, having information concerning M. pauliani and its habitat is necessary for effective conservation. Our study aimed to examine the population status of M. pauliani by verifying its geographic distribution and elevational range, exploring habitat use, and assessing threats. M. pauliani occurs from 1900 m to 2378 m a.s.l. and is most abundant at an altitude between 1993 and 2166 m. Adults, juveniles, and tadpoles were associated with different levels of stream depth, speed, and width. We found that human activities are contributing to habitat losses, which is modifying its environment and threatening the species’ survival. The data collected on the occurrence and habitat use of M. pauliani serve as an “environmental alert dashboard” to promote sustainable conservation. ABSTRACT: Mountain summits in Madagascar generally have species with specific habitat requirements, providing a home to a unique and locally endemic herpetofauna. Among them is M. pauliani, a typically aquatic and critically endangered amphibian found on the Ankaratra Massif. This species inhabits high elevations with a limited distribution range. Our study aimed to present new data on the distribution and elevational range, habitat use, and threats to M. pauliani and its occurrence according to habitat changes. To achieve this, annual monitoring was carried out from 2018 to 2021. Nine 100 m transects were established along streams at elevations ranging from 1762 to 2378 m a.s.l. along which we conducted visual encounter surveys. Data analysis was performed using a χ(2) test and Factor Correspondence Analysis. We found that M. pauliani occupies elevations between 1900 and 2378 m a.s.l. within humid forests and savannah habitats. The results showed a fluctuation in the number of animals observed and a higher occurrence at higher elevations throughout the years according to the season, stream quality, and water volume. Ongoing habitat alteration makes M. pauliani vulnerable to population decline, with annual bushfires likely having a negative impact on habitat.