Digging energetics in the South American rodent Ctenomys talarum (Rodentia, Ctenomyidae)

Ctenomys is the most speciose among subterranean rodents. There are few studies on energetics of Ctenomys, and none of them have focused on the energetics of digging. The present study aims to quantify the energetic cost of burrowing in Ctenomys talarum in natural soil conditions and to compare the energetics data with those reported for other subterranean rodents. Digging metabolic rate (DMR) in gravelly sand for C. talarum was 337.4 +/- 65.9 mL O-2-h(-1) (mean +/-SD). No differences in DMR were detected between sexes. Moreover, DMR was 295.9% of resting metabolic rate. In terms of a cost of burrowing model, the mass of soil removed per distance burrowed (M-soil) in gravelly sand was 44.5 +/- 6.7 g(.)cm(-1). Coefficients of the equation that related the energy cost of constructing a burrow segment of length S and M-soil(E-seg/M-soil) were K-s = 0.33 +/- 0.32 J(.)g(-1), which is the energy cost of shearing 1 g of soil, and K-p = 0.0055 +/- 0.0042 J(.)g(-1.)cm(-1), which is the energy cost of pushing 1 g of soil 100 cm. Regarding the cost of burrowing model, our data showed that C. talarum has the lowest DMR in gravelly sand among unrelated subterranean rodents analyzed. Moreover, despite C. talarum feeding aboveground, the foraging economics was similar that of to other rodents.