Octodon degus (common name: degu) It is a native diurnal rodent endemic to central Chile, belonging to the infraorder Hystricognathi, which is a far apart rodent group in relation to rodents such as squirrels and Norway rat. Degus are social rodents that build and live in underground galleries, connected above ground by a system of runways (Fulk, 1976, Vasquez et al. 2002). They use their burrows overnights and when escaping from predators (such as raptors of foxes). The typical habitat in central Chile where degus live comprises sparse vegetation, and most of their daytime activities take place above ground on open habitat between shrubs or under shrubs which provide lower predation risk compared to open areas (see Fulk 1976; Lagos et al., 1995, Vasquez et al. 2002; Ebensperger & Hurtado 2005). In natural populations, degus reproduce once a year, and pups emerge from burrow around early Spring. Its diet is herbivorous, comprising several herbs and seeds. Degus show a seasonal modulation of basal cortisol in the wild associated with mating, suggesting an essential role of cortisol in adjusting the overall metabolism throughout different life history stages (Quispe et al. 2014; see also Ebensperger et al 2011). Although most populations are located under 1,000 m a.s.l., there are some populations living up to 2,600m a.s.l. (see Quispe et al. 2009, Ebensperger et al 2012). The geographic distribution of degus ranges from Huasco river in the north, with a desertic climate and populations located nearby river and creeks to the Maule river in the south, with a Mediterranean climate.