Ontogenetic development of burrowing and related behaviors in the subterranean rodent Ctenomys talarum (Caviomorpha: Ctenomyidae).

ALEJANDRA ISABEL ECHEVERRÍA; ALDO IVÁN VASSALLO

Mendoza, Argentina

Congreso; 10th Mammalogical Congress; 2009

IADIZA

The South American rodent Ctenomys talarum spend most of their lives within individual burrows. Social transmission from parents is not essential for the development of subterranean habits in this species. To assess the ontogeny of burrowing we observed isolated pups inside a seminatural enclosure with typical soil, from thermoregulatory independence (15 days) to dispersal age (~60 days). One pup from each wildcaughted mother’s litter was randomly chosen (N=11) and videorecorded every ~5 days. Scratching using the forelimbs spontaneously appeared in lactating pups when confronted with soil (15-20 days). During this period individuals removed small volumes of soil resulting in small holes. Latency and time dedicated to burrowing respectively decreased and increased with age (RM ANOVA; F2,29 = 8.2, p<0.01; F2,29 = 5.2, p<0.05). First burrow construction age ranged from 20 to 47 days (mean ± SD = 30.4 ± 8.9). These simple burrows, which included a main tunnel lacking branches, averaged 14.2 ± 7.6 cm in length, 10.0 ± 1.7 cm in depth and 4.8 ± 1.0 cm  in diameter. Nearly 23 days we observed the hindlimbs being used simultaneously stroking the earth and transporting substrate backwards from the tunnel entrance via an “inchworm” motion in reverse, a common behavior in adults. A postural change was observed from day 18 (mean ± SD = 28.4 ± 8.4), where individuals begun to explore by a rearing posture, a behavior that increased in frequency with age (r = 0.5, p<0.01). Reversal locomotion, which is suitable for motion within the reduced burrow’s space, appeared at 31-36 days. Post-weaning individuals (45-47 days) excavated complex burrows that included a main tunnel, one branch and a camera. Briefly, young tuco-tucos are capable to dig a burrow shortly after thermoregulatory independence. Related behaviors progressively appeared near dispersion, which may reflect a semialtricial development in C. talarum.