Stress and reproductive physiology in Canada lynx (Lynx canadensis): Implications for in-situ and ex-situ conservation

Species reintroductions are a valuable conservation tool, but such efforts often fail, and we have a poor understanding of why. Understanding the role of stress physiology in reintroductions may be critical for enhancing their success rates. The goal of my dissertation was to validate a technique for monitoring stress and reproductive physiology in Canada lynx, and apply this technique to a reintroduced lynx population. The non-invasive technique of fecal hormone analysis was used to accomplish four objectives: (1) investigate the effect of environmental and methodological factors on the quantification of fecal steroid metabolite concentrations, (2) establish normative patterns of male and female reproductive physiology in captive and wild lynx populations, (3) describe patterns of stress physiology in captive and wild lynx populations, and (4) examine changes in stress physiology of lynx throughout the reintroduction process, and investigate patterns of individual variation in stress responses. Validation experiments indicated that fecal steroid metabolites remain relatively stable in winter field conditions, even when exposed to repeated freezing and thawing. Thus biologically meaningful results can be obtained from fecal samples collected in the field. Canada lynx are highly seasonal breeders, and I found that both males and females exhibit seasonal increases in reproductive hormones (estrogens and androgens, respectively), which coincide with the breeding season. Progestogens, which are typically useful for monitoring pregnancy, were not useful indicators of pregnancy in Canada lynx. Nonetheless, they may accurately reflect luteal activity, as corpora lutea in Lynx species may persist for some time, although the dynamics of luteal activity are still poorly understood. Canada lynx are solitary in the wild, and group-housing in captivity appears to alter both reproductive and stress physiology. Population comparisons revealed that captive lynx exhibit higher concentrations of all four steroid hormones than wild populations, which may be linked to differences in energy regulation or metabolism. Finally, in reintroduced lynx, the magnitude of a lynx’ stress response is a significant predictor of post-release survival; lynx with larger stress responses have shorter post-release survival. Thus, fecal hormone analysis provides a valuable tool for monitoring the reproductive and stress physiology of Canada lynx. Furthermore, information gained using this technique can be used to guide the development of stronger management plans for captive and wild populations, thereby improving animal well-being and conservation