Measuring salivary cortisol in wild carnivores

• Published in: Hormones and behavior Vol. 137; p. 105082
• Main Authors: Montgomery, Tracy M., Greenberg, Julia R., Gunson, Jessica L., John, Kecil, Laubach, Zachary M., Nonnamaker, Emily, Person, Erin S., Rogers, Heidi, Ronis, Emily M., Smale, Laura, Steinfield, Katherine R., Strong, Robyn, Holekamp, Kay E., Beehner, Jacinta C.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2022
• Subjects: Animals; Animals, Wild; Carnivora; Cortisol; Crocuta crocuta; Daily rhythms; Feces; Glucocorticoids; Hormone-behavior relationships; Hyaenidae; Hydrocortisone; Saliva; Spotted hyenas; Glucocorticoids; Daily rhythms; Cortisol; Spotted hyenas; Saliva; Crocuta crocuta; Hormone-behavior relationships
• ISSN: 0018-506X; 1095-6867
• DOI: 10.1016/j.yhbeh.2021.105082

Salivary hormone analyses provide a useful alternative to fecal and urinary hormone analyses in non-invasive studies of behavioral endocrinology. Here, we use saliva to assess cortisol levels in a wild population of spotted hyenas (Crocuta crocuta), a gregarious carnivore living in complex social groups. We first describe a novel, non-invasive method of collecting saliva from juvenile hyenas and validate a salivary cortisol assay for use in this species. We then analyze over 260 saliva samples collected from nearly 70 juveniles to investigate the relationships between cortisol and temporal and social variables in these animals. We obtain some evidence of a bimodal daily rhythm with salivary cortisol concentrations dropping around dawn and dusk, times at which cub activity levels are changing substantially. We also find that dominant littermates have lower cortisol than singleton juveniles, but that cortisol does not vary with age, sex, or maternal social rank. Finally, we examine how social behaviors such as aggression or play affect salivary cortisol concentrations. We find that inflicting aggression on others was associated with lower cortisol concentrations. We hope that the detailed description of our methods provides wildlife researchers with the tools to measure salivary cortisol in other wild carnivores. •We validated methods for collecting and analyzing saliva from wild carnivores.•We provide support for a bimodal daily rhythm in juvenile spotted hyena cortisol.•Cortisol varied among juvenile hyenas based on litter size and intra-litter rank.•Inflicting aggression on others was associated with lower cortisol concentrations.