Ebensperger, L.A. et al.: Grouping increases the ability of the social rodent, Octodon degus, to detect predators when using exposed microhabitats

Luis A. Ebensperger, Petra K. Wallem: Grouping increases the ability of the social rodent, Octodon degus, to detect predators when using exposed microhabitats.
In: Oikos Volume 98, Issue 3, pages 491–497, September 2002.

Link: http://onlinelibrary.wiley.com/doi/10.1034/j.1600-0706.2002.980313.x/pdf

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Abstract

We examined the hypothesis that a main benefit of group-living in the hystricognath rodent, Octodon degus (common degu), is to decrease individual risk of predation. During a first series of field observations, we contrasted group size of degus when using covered microhabitats with that of degus using exposed patches. During a second set of field observations, we assessed how distance to detection and to escape by degus varied with group size upon the approach of a potential human predator. Degus in exposed patches formed larger groups than degus in covered microhabitats. After excluding the influence of nearest burrow to focal subjects, we found that degus of larger groups detected an approaching human predator at a greater distance than degus of smaller groups. Likewise, degus of larger groups escaped to nearby burrows at a greater distance from the approaching predator than degus of smaller groups. All these pieces of evidence support the predatory risk hypothesis according to which group-living in degus functions to reduce the risk of predation