Measuring salivary cortisol in wild carnivores

ABSTRACTSalivary 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 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 either subordinate littermates or singletons, 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.HIGHLIGHTSWe validated methods for collecting and analyzing saliva from wild carnivores.We documented a bimodal daily rhythm in juvenile spotted hyena salivary cortisol.Cortisol varied among juvenile hyenas based on litter size and intra-litter rank.Inflicting aggression on others was associated with lower cortisol concentrations.

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Aerodynamic and Acoustic Voice Measures Before and After an Acute Public Speaking Stressor

Journal of Speech Language and Hearing Research ◽

10.1044/2020_jslhr-19-00252 ◽

2020 ◽

Vol 63 (10) ◽

pp. 3311-3325

Author(s):

Brittany L. Perrine ◽

Ronald C. Scherer

Keyword(s):

Fundamental Frequency ◽

Salivary Cortisol ◽

Public Speaking ◽

Stress System ◽

Before And After ◽

Subglottal Pressure ◽

Response To Stress ◽

System Activation ◽

Speaking Fundamental Frequency ◽

Pituitary Adrenal Axis

Purpose The goal of this study was to determine if differences in stress system activation lead to changes in speaking fundamental frequency, average oral airflow, and estimated subglottal pressure before and after an acute, psychosocial stressor. Method Eighteen vocally healthy adult females experienced the Trier Social Stress Test (TSST) to activate the hypothalamic–pituitary–adrenal axis. The TSST includes public speaking and performing mental arithmetic in front of an audience. At seven time points, three before the stressor and four after the stressor, the participants produced /pa/ repetitions, read the Rainbow Passage, and provided a saliva sample. Measures included (a) salivary cortisol level, (b) oral airflow, (c) estimated subglottal pressure, and (d) speaking fundamental frequency from the second sentence of the Rainbow Passage. Results Ten of the 18 participants experienced a hypothalamic–pituitary–adrenal axis response to stress as indicated by a 2.5-nmol/L increase in salivary cortisol from before the TSST to after the TSST. Those who experienced a response to stress had a significantly higher speaking fundamental frequency before and immediately after the stressor than later after the stressor. No other variable varied significantly due to the stressor. Conclusions This study suggests that the idiosyncratic and inconsistent voice changes reported in the literature may be explained by differences in stress system activation. In addition, laryngeal aerodynamic measures appear resilient to changes due to acute stress. Further work is needed to examine the influence of other stress systems and if these findings hold for dysphonic individuals.

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