Abstract

CAMPOS, Valeria E et al. Is availability of trophic resources related to crevices selected by Octomys mimax in the monte desert?. Mastozool. neotrop. [online]. 2015, vol.22, n.2, pp.279-287. ISSN 0327-9383.

Rocky habitats have a particular microclimate and a highly complex structure, providing sites that mammals can use as dens or as nesting sites to raise their young. The complex topography of these habitats also favors water retention, thereby promoting growth of plants. The viscacha rat (Octomys mimax; Rodentia, Octodontidae) is a rock-dwelling hystricognath rodent that lives in rocky crevices with high vegetation cover. We hypothesized that viscacha rat selects crevices with high availability of plants included in the diet. To test this, we analyzed the diet of the viscacha rat and compared the availability of consumed plant species between used and available crevices. The diet of this species is composed mainly of leaves of shrubs and trees, includes cacti throughout the year and seeds and fruits, principally Prosopis spp., in the wet season. The food items present in caches confirmed the results obtained from microhistological analysis, with the addition of Ramorinoa girolae and Halophytum ameghinoi. This rodent takes advantage of consuming and storing avail­able items, behaving as an opportunistic species. Selected plant species were similar in abundance in used and available crevices; consequently, crevices are likely selected for other characteristics such as thermal benefits, an important constraint in desert environments.

Keywords : Desert environment; Habitat selection; Rock-dwelling mammal; Viscacha rat.

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