Is availability of trophic resources related to crevices selected by Octomys mimax in the Monte desert?

CAMPOS, V. E.; GIANNONI, S.M.; REUS, L.; DIAZ ISENRATH, G. B.; CAMPOS, C. M.

MASTOZOOLOGíA NEOTROPICAL

UNIDAD DE ZOOLOGÍA Y ECOLOGÍA ANIMAL, INSTITUTO ARGENTINO DE INVESTIGACIÓN DE LAS ZONAS ARIDAS, CRICYT, CONICET

Lugar: Mendoza; Año: 2015 vol. 22 p. 279 - 287

0327-9383

Rocky habitats have a particular microclimate and a highly complex structure and thus provide sites which mammals can use as nesting sites or dens to raise their young. The complex topography of these habitats allows for increased humidity, which promotes high abundance of plant species. The viscacha rat (Octomys mimax; Rodentia, Octodontidae) is a rock-dwelling hystricognath rodent that lives in rocky crevices with high vegetation cover. Our objectives were 1) to analyze composition of the viscacha rat?s diet and 2) to compare availability of consumed plant species between used and available crevices. Our results showed that the diet is composed mainly of leaves of shrubs and trees, and that it includes cacti throughout the year and seeds and fruits in the wet season, principally Prosopis spp. The food items present in caches confirmed the results obtained from microhistological analysis, and there was the addition of Ramorinoa girolae and Halophytum ameghinoi. This rodent takes advantage of consuming and storing available items and thus it behaves as an opportunistic species. We found no evidence to support the hypothesis that the viscacha rat selects crevices with high food resource availability, so it probably selects them because they offer some other advantage such as thermal benefits, an important constraint in desert environments.