Population Dynamics of Neotropical Small Mammals in Seasonal Habitats

Abstract

Responses of Neotropical small-mammal populations to seasonal and yearly variations in climate, plant phenology, and habitat conditions were examined. Populations of rodent and marsupial species were studied for 2 years in premontane forest (11 species) and llanos (plains; seven species) habitats in northern Venezuela. Although rainfall at both habitats was seasonal, wet-dry seasonality and seasonal changes in habitat conditions were more pronounced in the llanos habitat. Populations of all small-mammal species fluctuated in response to seasonal and yearly variations. The timing and magnitude of these fluctuations were related to population traits and ecology of each species. Within each habitat some species were resident, whereas others were transient. Although rodent species from both habitats bred year-round, most exhibited a reproductive peak in the wet season. The marsupial species, in contrast, reproduced only in the wet season. Seasonal flooding and mosaic habitat structure of the llanos placed certain constraints on the population dynamics of the small mammals from this habitat. All terrestrial species of the llanos exhibited population traits of colonizing species. This was not the case for the terrestrial species in the premontane forest habitat.