New ecological evidence for <i>Telmatobius pefauri</i> reveals a high level of threat to its populations in the Pre-Puna region of northern Chile

Telmatobius pefauri is an endemic species from the Pre-Puna region of northern Chile, currently listed as Critically Endangered. We intensively monitored four localities to assess microhabitat, relative abundance, biometry, diet, and threats. Additionally, four other sites in this geographic region were surveyed to better define its distribution. The species inhabits small mountain streams with clear, cold, slightly alkaline waters and low stream discharge. Relative abundance was low in two localities, moderate in one, and absent in recent years at another. Sexual dimorphism was evident in body size and mass, and the body condition remained stable across seasons. Diet composition and prey preference varied seasonally in one of the surveyed localities. All localities had irrigation ponds, with amphibian abundance showing a negative correlation with pond surface area. These findings provide critical ecological information to guide conservation strategies for this poorly known high-Andean anuran.