Glucocorticoid response to changes in enclosure size and human proximity in the Persian onager (Equus hemionus onager)

Abstract

This study investigated glucocorticoid (GC) responses to season and changes in enclosure size and human proximity in the Persian onager (Equus hemionus onager). Enzyme immunoassays were validated to measure GC metabolites in urine and feces (fGCM). Fecal samples were collected from 10 female onagers while in a large pasture, after transport to smaller yards (in greater proximity to people), and 2 months thereafter. Urine samples were collected for 1 year while females were in smaller yards to examine seasonal GC activity. Approximately, 2-fold increases (P < 0.05) were observed in fGCM levels after transport from pasture to yards with increased human exposure, followed by a rapid decline (within -17 days) to baseline (pasture) values. However, responses varied among onagers during the 30 days after translocation, with one female failing to acclimate. Mean fGCM concentrations in smaller yards 2 months after transport were comparable to those in pasture. Seasonal GC concentrations were lowest (P < 0.05) during winter, indicating modest seasonal variability. Results demonstrate an acute increase in GC secretion in Persian onagers that moved from large to small enclosures coincident with increased human activities. Most animals acclimated within 3 weeks, suggesting that this rare equid has retained mechanisms to acclimate to marked alterations in an ex situ environment.

The effect of fluphenazine decanoate on glucocorticoid production, reproductive cyclicity, and the behavioral stress response in the Persian onager (Equus hemionus onager)

“…However, because plasma provides a near‐instantaneous measure and urine is a pooled measure over time, these results likely indicate the same overall effect. We also observed individual variation in the adrenocortical response to handling during the control and treatment periods, similar to previous reports from our laboratory in which individual onagers demonstrated variation in both baseline glucocorticoid metabolites and the length and magnitude of the responses to changes in enclosure size and management (Vick et al, ). It is also possible that individuals had variable sensitivities to FD.…”

“…With fewer than 1,000 onagers in the wild and a currently unsustainable population of only ≈100 zoo‐housed onagers (Volz et al, ), this was an important step toward maintaining genetic diversity in the captive population as an insurance policy against extinction. However, during handling for reproductive management, onagers produced acute peaks in urinary cortisol and exhibited anecdotally reported nervous behaviors (e.g., pacing, weaving and head rolling; Vick et al, ). Furthermore, the female in which AI was not successful had significantly higher cortisol levels than the other two females that carried to term (unpublished data).…”

Assessing the impact of live-capture, confinement, and translocation on stress and fate in eastern gray squirrels

“…Recaptured squirrels were no longer making large exploratory movements, and hence they were likely less stressed than the squirrels making larger exploratory movements. The capacity to adapt to a new environment is likely species dependent (Hartup et al 2005;Franceschini et al 2008;Dickens et al 2009;Vick et al 2012). We expect that the success of translocation will very much depend on the environment into which the animals are introduced, and on the social structure of the species.…”

Fundamental Studies of the Reproductive Biology of the Endangered Persian Onager (Equus hemionus onager) Result in First Wild Equid Offspring from Artificial Insemination1

“…Our ultimate focus was on AI, largely because the greatest challenge to creating a sustainable population is dealing with onagers living in geographically dispersed locations. This species is sensitive to acute stressors [46] such as animal transport. Therefore, the ability to produce offspring by transporting semen (rather than the animals themselves) could improve reproductive efficiency while maintaining heterozygosity to preserve species integrity.…”