Communal burrowing in the hystricognath rodent, Octodon degus: a benefit of sociality?

We examined the hypothesis that a main benefit of group-living in the semif ossorial rodent, Octodon degus (Rodentia: Octodontidae), is to decrease ind ividual cost of burrow construction. We contrasted the digging behavior of groups of three same-sex, adult-sized individuals with that of solitary deg us. The behavior of singles and trios was recorded inside a large terrarium partially filled with natural soil and under controlled conditions of food , light, and temperature. The observation that degus in groups do not decre ase their burrowing time or frequency of digging compared with solitary dig gers does not support the hypothesis that communal burrowing is a primary c ause of degu sociality. On the other hand, the observation that degus in gr oups removed significantly more soil per capita than solitary digging degus , and that grouped individuals coordinated their digging - group members bu rrowed mostly in the same sites and formed digging chains -, suggests that social burrowing may potentially reduce the cost of burrow construction in the long term. We suggest that such longterm benefits will be a consequence rather than a cause of degu group-living.