Spatial and temporal variation in population dynamics of Andean frogs: Effects of forest disturbance and evidence for declines

Background/Question/Methods

Amphibians have some of the highest rates of population decline and extinction of any taxonomic group yet major knowledge gaps remain for many of the most threatened species and regions in the world. Ecuador houses the highest density of described amphibian species in the world and many of those species are at high risk for extinction. However, rigorous estimates of population parameters are lacking for many amphibian species in the Neotropics. Our aim was to determine how the demography of seven species of the genus Pristimantis varied over time and space in two forests in the Ecuadorian Andes. From 2002-2009, we completed a long-term capture-mark-recapture study to estimate abundance, survival, and population growth rates. We tested three hypotheses, 1) population declines have occurred in some Pristimantis species in Ecuador from 2002-2009, 2) differences in apparent survival and population growth rates of Pristimantis species exist at both local and landscape scales, and 3) survival and abundance differs among species. 

Results/Conclusions

Our results showed spatial and temporal variation in population parameters by species and sex. P. bicantus experienced significant reductions in abundance over the course of our study. Population abundance was higher following the wet season. Our results showed that forest type and forest fragmentation both within and adjacent to monitoring grids negatively affects the abundance, apparent survival, and population growth rate of three Pristimantis species. Loss of primary forest habitat poses a real threat to Pristimantis species and may results in their population decline and extinction in Ecuadorian cloud forests. The results of our study raise concerns for the population status of understudied amphibian groups while providing insights into the population dynamics of Neotropical amphibians.