Effects of population density on corticosterone levels of prairie voles in the field.
High population density is often associated with increased levels of stress-related hormones, such as corticosterone (CORT). Prairie voles (Microtus ochrogaster) are a socially monogamous species known for their large population density fluctuations in the wild. Although CORT influences the social behavior of prairie voles in the lab, the effect of population density on CORT has not previously been quantified in this species in the field. We validated a non-invasive hormone assay for measuring CORT metabolites in prairie vole feces. We then used semi-natural enclosures to experimentally manipulate population density, and measured density effects on male space use and fecal CORT levels. Our enclosures generated patterns of space use and social interaction that were consistent with previous prairie vole field studies. Contrary to the positive relationship between CORT and density typical of other taxa, we found that lower population densities (80 animals/ha) produced higher fecal CORT than higher densities (240/ha). Combined with prior work in the lab and field, the data suggest that high prairie vole population densities indicate favorable environments, perhaps through reduced predation risk. Lastly, we found that field animals had lower fecal CORT levels than laboratory-living animals. The data emphasize the usefulness of prairie voles as models for integrating ecological, evolutionary, and mechanistic questions in social behavior.
Department of Biology, University of Florida, Gainesville, FL 32611, USA; Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA; Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, USA. Electronic address: dimitri.blondel@duke.edu.
Dimitri V
DV
Blondel
Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA.
Gerard N
GN
Wallace
Department of Biology, University of Florida, Gainesville, FL 32611, USA; Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA.
Stefanie
S
Calderone
Department of Biology, University of Florida, Gainesville, FL 32611, USA; Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA.
Marija
M
Gorinshteyn
Department of Biology, University of Florida, Gainesville, FL 32611, USA.
Colette M
CM
St Mary
Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA.
Steven M
SM
Phelps
D000818:Animals; D003411:Arvicolinae / Q000378:metabolism*; D001522:Behavior, Animal / Q000502:physiology*; D003345:Corticosterone / Q000378:metabolism*; D005243:Feces / Q000737:chemistry; D005260:Female; D065948:Grassland; D008297:Male; D011156:Population Density; D012919:Social Behavior
D003345:Corticosterone
Corticosterone; Fecal hormone assay; Microtus ochrogaster; Population density; Prairie vole; Stress