Maternal and social status affect hair cortisol concentrations in brown bears

Abstract

Hair cortisol concentration is affected by different biological factors, including age, sex, and reproductive status, and can provide important insights into fitness. Using cortisol concentrations of wild Scandinavian brown bears, Ursus arctos, the purpose of this study was to investigate cortisol variations among individuals in relation to age, sex, and reproductive status (solitary individuals vs individuals in a family group). Cortisol concentrations were measured in 448 hair samples of 303 brown bears (162 males and 141 females, from one to nine years of age) captured from 1990 to 2016. We found that members of family groups, i.e., mothers as well as their dependent offspring, had significantly higher cortisol concentrations compared to solitary individuals (males or females). Higher energetic costs in family groups are likely linked to growth of the offspring as well as maternal costs incurred by the rearing of offspring. Our findings provide valuable insights into the physiological effects of maternal care and reproductive status in mammals.

Keywords

Brown bear; Cortisol; HPA axis activity; Physiological response; Reproduction; Scandinavia; Ursus arctos

Published in

Zoology
2025, volume: 169, article number: 126257
Publisher: ELSEVIER GMBH

SLU Authors

• Kindberg, Jonas

  • Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
    
  • Norwegian Institute for Nature Research (NINA)

UKÄ Subject classification

Medical Bioscience
Zoology

Publication identifier

• DOI: https://doi.org/10.1016/j.zool.2025.126257

Permanent link to this page (URI)

https://res.slu.se/id/publ/141462