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

MARÍA ZUBILLAGA; SKEWES, OSCAR; NICOLAS SOTO; JORGE RABINOVICH

F1000Research

F1000Research

Año: 2014 vol. 2

2046-1402

We analyzed the effects of population density and climatic variables on the rateof population growth in the guanaco (Lama guanicoe), a wild camelid species inSouth America. We used a time series of 36 years (1977-2012) of populationsampling in Tierra del Fuego, Chile. Individuals were grouped in threeage-classes: newborns, juveniles, and adults; for each year a femalepopulation transition matrix was constructed, and the population growth rate (λ)was estimated for each year as the matrix highest positive eigenvalue. Weapplied a regression analysis with finite population growth rate (λ) asdependent variable, and total guanaco population, sheep population, annualmean precipitation, and winter mean temperature as independent variables,with and without time lags. The effect of guanaco population size wasstatistically significant, but the effects of the sheep population and the climaticvariables on guanaco population growth rate were not statistically significant.