Effects of Radio‐Collars are not Contingent on Socioecological Conditions in Degus

Abstract

ABSTRACTSpecies‐specific research on free‐ranging mammals reveals a diversity of effects of radio‐collars on behavior, body condition, and fitness. Although these studies indicate rather limited direct effects, radio‐collars may cause effects influenced by socio‐ecological conditions. Using a 7‐year study on a natural population of group‐living degus (Octodon degus), we tested the hypothesis that ecological (food availability, burrow density) and social (group size, group male‐to‐female ratio) conditions modulate effects of radio‐collars on body condition (e.g., body mass, ecto‐ and endoparasite loads, fecal cortisol metabolites) and direct fitness (litter size, adult survival). We determined the effect of radio‐collar use on degus by contrasting the presence or absence of radio‐collars, quantifying the effects of the number of days carrying a radio‐collar, and the relative mass of radio‐collars worn by degus in central Chile between 2009 and 2015. Radio‐collar use was not associated with direct effects on litter size, adult survival, or with body mass and fecal cortisol metabolites but was linked to low ecto‐ and endoparasite loads. These seemingly positive effects may reflect decreased mobility, or a research bias for radio‐collaring larger, healthier individuals. There was no evidence that ecological and social conditions modulated radio‐collar effects on degu body condition and direct fitness. These findings are consistent with evidence from other mammal studies that reported no appreciable detrimental direct or indirect effects of radio‐collars. © 2021 The Wildlife Society.