The Montseny brook newt (Calotriton arnoldi) is one of the most endangered amphibians in Europe, and most aspects of its biology and population dynamics are little known. We estimated the demographic parameters of the species at two distinct sites encompassing the environmental variability in habitat features by using a capture-recapture Huggins robust design model. Despite the small distribution range occupied by this endemic newt, we found differences in survival, emigration and population size between the two sites. We suggest that these differences may be related to the spatial heterogeneity relative to the hydroperiod, the rocky structure of the streambed, and forest productivity along the streams. However, it is unknown whether the demographic differences may drive different population dynamics and from a conservation point of view, different extinction probabilities.