PORTAL ORIENTATION AND ARCHITECTURE OF BURROWS IN TYMPANOCTOMYS BARRERAE (RODENTIA, OCTODONTIDAE)

The red viscacha rat, Tympanoctomys barrerae , is an octodontid rodent endemic to the Monte and Patagonian deserts of Argentina. It lives in burrows with numerous portals facing different directions. We studied climatic factors as possible determinants of burrow architecture and portal orientation, in 2 populations. Climatic factors examined were sunlight, direction of sun’s rays, and wind frequency and intensity. Variables analyzed for burrow architecture were portal orientation, slope, and depth at the 1st turn. Mean number of portals per burrow was significantly different between populations. Burrows had few portals oriented toward predominantly cold and intense winds. More portals faced direct solar light in winter. Burrows are so constructed as to allow openings to receive direct sunlight in winter and indirect sunlight in summer.