ESTIMATION OF SEX-RELATED AND AGE-RELATED SURVIVAL RATES IN A MICROTINE POPULATION

Little is known about the sex- and age-related survival rates of microtine rodents. Thus, we used probabilistic models and recent software developments to estimate survival rates in a Mediterranean pine vole (Microtus duodecimcostatus) population studied by capture-recapture. Goodness-of-fit tests revealed that erratics (voles caught only once) were captured during every trapping-session. Removal of the erratics from the data was necessary for application of the Jolly-Seber model. The model was selected according to parsimony criteria, which assumes a higher survival rate for juvenile males than juvenile females. Survival rates were higher among adults of both sexes than among juveniles, but there was no influence of sex on adult survival rate. These variations in survival rates can be related to demographic traits of the Mediterranean pine vole (i.e., relative abundance in different habitats, local population dynamics). Our data also suggest that the regional abundance of the Mediterranean pine vole is determined by ''source-sink dynamics.''