The Adrenal Cortisol Response to Increasing Ambient Temperature in Polar Bears ( Ursus maritimus )

Our objective was to identify the upper ambient temperature threshold that triggers an increase in cortisol in response to increased thermoregulatory demands in polar bears. The results reported here include endocrine data collected over two years from 25 polar bears housed in 11 accredited zoologic...

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Bibliographic Details
Published in:Animals
Main Authors: Emily M. Leishman, Maria Franke, Jill Marvin, Dylan McCart, Carol Bradford, Zoltan S. Gyimesi, Anne Nichols, Marie-Pierre Lessard, David Page, C-Jae Breiter, Laura H. Graham
Format: Article in Journal/Newspaper
Language:English
Published: MDPI AG 2022
Subjects:
thermoregulation
climate change
glucocorticoid
HPA axis
conservation
Veterinary medicine
SF600-1100
Zoology
QL1-991
Ursus maritimus
Online Access:https://doi.org/10.3390/ani12060672
https://doaj.org/article/f22fa5d891284a06841e7b19aa12a4c9
Description
Summary:Our objective was to identify the upper ambient temperature threshold that triggers an increase in cortisol in response to increased thermoregulatory demands in polar bears. The results reported here include endocrine data collected over two years from 25 polar bears housed in 11 accredited zoological institutions across North America. The effects of ambient temperature, sex, age group (juvenile, adult, elderly), breeding season and humidity on fecal cortisol metabolite (FCM) concentrations (N = 8439 samples) were evaluated using linear mixed models. Ambient temperatures were placed into five different categories: <5 °C, 6–10 °C, 11–15 °C, 16–20 °C, and >20 °C. Ambient temperature and humidity had a significant ( p < 0.05) effect on FCM concentrations with significant ( p < 0.05) interactions of sex, age and breeding season. Once biotic factors were accounted for, there was a significant ( p < 0.05) increase in FCM concentrations associated with ambient temperatures above 20 °C in adult polar bears. The implications of these findings for the management of both zoo and wild polar bears are discussed.

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