The influence of group size on natal dispersal in the communally rearing and semifossorial rodent, Octodon degus

Verónica Quirici, Sylvain Faugeron, Loren D. Hayes, Luis A. Ebensperger

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

In social or group living species, members of groups are expected to be affected differentially by competition through the effect of group size (i. e., the "social competition hypothesis"). This hypothesis predicts an increase in the probability of dispersal with increasing size of social groups. At a more mechanistic level and based on the known effects of competition on stress hormone levels, a positive relationship between group size and glucocorticoids of juveniles should be observed. We used a demographic approach to test these predictions on a natural population of the communally rearing and semifossorial rodent-Octodon degus. Burrow systems provide degus with places to rear offspring and to evade stressful thermal conditions and predators. Thus, we predicted dispersal to increase with increasing number of degus per main burrow system used, a measure of habitat saturation in degus. The probability of dispersal increased with increasing number of degus per main burrow system used. Mean fecal metabolites of cortisol in offspring increased, yet not statistically significantly, with the number of juveniles in groups. These results were consistent with a scenario in which competition drives natal dispersal in juveniles in social degus. In particular, competition would be the consequence of high degu abundance in relation to the abundance of burrow systems available at the time of offspring emergence.

Original languageEnglish
Pages (from-to)787-798
Number of pages12
JournalBehavioral Ecology and Sociobiology
Volume65
Issue number4
DOIs
Publication statusPublished - Apr 2011

Keywords

  • Dispersal
  • Fecal cortisol metabolites
  • Group size
  • Octodon degus

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology

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