Density but not climate affects the population growth rate of guanacos ( ) ( Artiodactyla , Camelidae )

We analyzed the effects of population density and climatic variables on the rate of population growth in the guanaco ( ), a wild camelid species in Lama guanicoe South America. We used a time series of 36 years (1977-2012) of population sampling in Tierra del Fuego, Chile. Individuals were grouped in three age-classes: newborns, juveniles, and adults; for each year a population transition matrix was constructed, and the population growth rate (λ) was estimated for each year as the matrix highest positive eigenvalue. We applied a stepwise regression analysis with population growth rate (λ) as dependent variable, and total guanaco population (in natural logs), annual mean precipitation, and winter mean temperature as independent variables, with and without time lags. The effect of population size was statistically significant, but the effect of the climatic variables on guanaco population growth rate was not significant. 1 2 3