Personality and stress physiologyfecal glucocorticoid metabolite concentrations are associated with post-release fitness in translocated swift foxes (Vulpes velox)

Kimberly R Todd^1,2,3*Elizabeth W Freeman⁴Hila Shamon^3,5Dana L Nelson^3,6Jessica Alexander³William J McShea³Melissa Songer³Tevin Messerly⁷Steve Paris³Nucharin Songsasen³

• ¹Aaniiih Nakoda College, Agency, United States
• ²George Mason University Department of Environmental Science and Policy, Fairfax, United States
• ³Smithsonian's National Zoo and Conservation Biology Institute, Washington, United States
• ⁴George Mason University School of Integrative Studies, Fairfax, United States
• ⁵Duke Farms, a Center of the Doris Duke Foundation, Hillsborough, United States
• ⁶Clemson University Department of Forestry and Environmental Conservation, Clemson, United States
• ⁷Fort Belknap Fish and Wildlife Department, Harlem, United States

Conservation translocations can promote species recovery but are prone to failure due to low post-release survival. Mounting evidence suggests that intrinsic attributes like personality and stress physiology can impact how individuals cope with translocation and acclimatize to the release site. Here, we investigated relationships among personality, biomarkers of stress, post-release movement, and survival using a recent swift fox (Vulpes velox) reintroduction program as a case study. We scored pre-release behavioral responses to handling and collected fecal samples (n = 329) from 76 foxes translocated from three wild populations across Colorado and Wyoming to the Fort Belknap Reservation, Montana, in 2021-2022. Our behavioral assessments measured the degree to which foxes were proactive (i.e., active, risk-taking, less docile) or reactive (i.e., inactive, risk-averse, more docile). We quantified fecal glucocorticoid metabolite (fGM) concentrations for the first time in swift foxes and monitored foxes' post-release movements and survival using GPS data. Generalized linear models indicated that foxes with the lowest and highest fGM concentrations were more reactive during handling. Further, foxes with higher fGM concentrations around the time of capture traveled greater cumulative distances post-release. Personality had a non-linear effect on survival such that foxes with the most proactive and reactive behaviors during handling were more likely to survive in the first 60 days post-release. Ultimately, release cohorts comprising an array of individual temperaments may best cope with the novelty of the release site through behaviorally mediated resource partitioning and risk avoidance.