Identifying threats to Pyrenean brook newt (Calotriton asper) to improve decision making in conservation management: A literature review complemented by expert-driven knowledge

For cryptic species, designing and implementing appropriate and effective conservation strategies is often difficult due to a lack of information about their ecology and biology. Combining scientific knowledge and expert judgments may help to address this issue. The Pyrenean brook newt (Calotriton asper) is an endemic amphibian of the Pyrenees mountain range (located in Andorra, France and Spain) and is listed as a vulnerable species on the national Red List of amphibians of metropolitan France. To ascertain a thorough understanding of the species’ current status, we identified its major threats in France using both (1) scientific knowledge about the species through an extensive literature review and (2) the expert judgments of naturalists and environmental managers through semi-structured interviews. This study highlights seven key threats (climate change, diseases, species introduction and translocation, water quality, logging industry, hydraulic activity, recreational aquatic activities) with varying levels of importance depending on whether they were mentioned by experts or published in the scientific literature. Climate change appears to be the most commonly studied threat by scientists, whereas the logging industry and fish species introduction and translocation were the major threats identified by the experts. The fact that experts and scientists conduct studies at a different spatial scale (local and global, respectively) can partly explain this difference. This extensive study provides a decision support tool for the Pyrenean brook’s newt conservation and encourages the identification of consensual decisions. Given that the threats identified towards the Pyrenean brook newt are the same as those towards other endangered species in the Pyrenees, conservation measures already exist and probably benefit this species.