Biology of the chinchilla rats Abrocoma schistacea and A. uspallata (Caviomorpha, Abrocomidae): an eco-morphological-behavioral approach.

24. TARABORELLI PAULA; MORENO PABLO; OYARCE CARLOS; SASSI PAOLA; DACAR MARIA ANA; SANDOBAL ANA; MARTINEZ MARIANA AND OJEDA RICARDO.

Mendoza, Argentina

Congreso; The 10 th International Mammalogical Congress; 2009

IADIZA

The family Abrocomidae is endemic to South America, distributed over the central West, from Southern Peru to central Argentina; and includes six rock-specialist rodent species. The objectives of the present study were to characterize habitat, behaviour and morphology of populations of A. schistacea (31º45´24´´S, 69º13´28´´W, El Leoncito, San Juan Province) and A. uspallata (32º37´216´´S, 69º17´93´´W, Uspallata, Mendoza Province). We carried out live-trapping, tagging and recapture during 2006-2008. Standard body measurements, sex and age were determined for 10 A. schistacea and one A. uspallata. Burrows and vegetation were described. Diet composition was defined through micro-histological analyses of fresh faeces (N=27). The activity of A. schistacea was recorded by 17 footprint traps and 6 camera traps. Both species inhabit rock crevices along the pre-Andean foothills of the Monte desert. We found that A. schistacea lives in groups of 3-4 individuals, one male and two females or two males and two females (N=3). Some of their specializations for saxicolous life, such as morphology, foot pads for better traction on rocky surfaces and reduced nails are convergent with those of other saxicolous species. Both species appear to be at least nocturnal and crepuscular, if not occasionally diurnal. The A. schistacea population showed a density of 0.15±0.06 ind/ha. Dietary results of both species suggest trophic specialization due to a high proportion of creosotebush (Larrea sp., 30-90%). Width of the trophic niche was greater at El Leoncito (0.61±0.01, poor offer of trophic items) than Uspallata (0.42±0.06, higher cover and diversity of plant species) as expected from the theory that herbivores become more selective in richer trophic environments. The threats to these species are unknown and they are data deficient on the IUCN Red List. Protection of their populations should be undertaken because of their low abundance, restricted distribution and high level of habitat and food specialization.