Influence of land use and artificial water bodies on the habitat use of Myocastor coypus and Hydrochoerus hydrochaeris in the Argentine Pampas

Abstract

The Pampas region of central Argentina has undergone profound changes in land use during the last 2?3 decades. We studied the influences of land use and artificial water bodies on the habitat use of two semiaquatic rodents, coypus (Myocastor coypus) and capybaras (Hydrochoerus hydrochaeris), in different ecological units of the Pampas. We sampled signs of activity of both species in a total of 231 transects (120 in spring, 111 in autumn) in 24 sites of the Flooding, Rolling and Inland Pampas. In each transect, we recorded the type of water body (artificial or natural) and the associated land use (crop or livestock). We modelled the probability of coypu/capybara presence at each site using generalized estimation equations. The probability of coypu?s occurrence in water bodies adjacent to livestock fields was lower during autumn (the season with low water availability) regardless of water body type. Moreover, coypus were positively associated with artificial water bodies and showed no differences among ecological units, which is consistent with its characterization as a frequent species in different types of aquatic habitats. Occurrence of capybaras was lower in water bodies adjacent to livestock fields and it differed among ecological units, evidencing the current expansion of its natural range. Our study suggests that the trend for increasing croplands in the Pampas Region, the displacement of livestock to wetland areas, and the creation of artificial water bodies affect the patterns of habitat use of coypu and capybara. For capybara, we report the colonization of new areas of the Inland Pampas, increasing its western range.