CONICET | Buscador de Institutos y Recursos Humanos

Interspecific competition may influence demographic parameters and affect population sizes of competing species. In this study, we evaluated the effect of Akodon azarae abundance on demographic parameters of otherassemblage species through capture-mark-recapture data (CMR). In addition, we assessed the effects of time fluctuation, anthropogenic disturbances (burning), climate (rainfall and temperature) and endogenous variables (sex and abundance) on those parameters. The study was carried out in a railway bank in central Argentina through monthly CMR surveys from November 2011 to May 2014. We estimated species abundance using Pradel?s closed population models throughout a robust design. We modeled recapture and survival probabilities by Cormack Jolly Seber models and seniority probabilities and population growth rates by Pradel?s models. Akodon azarae abundance showed an inverse pattern to Mus musculus and Calomys musculinus abundance. Population numbers of A. azarae declined after fire, whereas M. musculus and C. musculinus increased their numbers and became the most abundant species. Akodon azarae abundance did not affect any demographic parameters of the other species. Instead, time fluctuations, sex and temperature explained those parameters. Even though burning changed species population numbers for a short period of time, it did not affect demographic parameters of any species. Although A. azarae is considered a dominant species, we did not find evidence that its abundance affects the demography of other small mammal species. Railway banks would offer shelter and food for all species during the year, allowing them to avoid competition for available resources. However, anthropogenic disturbances can produce changes in the composition of small mammal assemblage since they affect habitat quality and allow invasive species such as the Mus musculus to establish.