Influence of temporal variation and seasonality on population dynamics of three sympatric rodents

Abstract

Population dynamics of small mammals can be strongly influenced by seasonality. Long-term studies are important in detecting population size variation in small mammals, and understanding the causes of that variation. We performed a six-year study to investigate fluctuations in population parameters (reproduction, recruitment, survival rates, abundance, and capture probability) of three rodent species at the core of the Brazilian cerrado domain. Small mammals were captured monthly within two grids during six years at Aguas Emendadas Ecological Station in the Federal District, Brazil. Model selection for explaining variation in rodent survival rates and capture probability was performed using MARK (Robust Design model). All three rodent species showed highest proportion of reproductive females in wet seasons. Calomys tener and T. lasiotis are seasonal and population size is higher in dry than in wet seasons, while the most abundant N. lasiurus had no seasonal patterns. Annual variation in abundance was also important for these three species. Thalpomys lasiotis declined over the six years of the study. These species showed highest survival estimates in the dry season. Our results reinforce the idea that not only climatic (rainfall and drought) events are linked to population numbers, survival rates, and capturability, but also that the life histories of the species can play an important role in their responses to variations in rainfall-productivity events.