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Translocation stress in Stephens' kangaroo rats : how individual variation influences success Baker, Liv

Abstract

Wildlife translocation involves the relocation of free-ranging animals from one area to another. It is commonly used to combat species loss. However, its outcomes are poor; some reviews put the success rate as low as 10-25%. This is likely influenced by a lack of attention to individuals. Translocations involve some combination of stressors (e.g., capture, captivity, monitoring, environmental change). Although animals have evolved behavioural and physiological mechanisms to manage challenges, the combination of stressors during translocation can compromise these coping mechanisms. Personality should have significance for translocations as individuals with certain personality types and life experience may handle translocation stressors better than others. The aim of this thesis was to profile individual Stephens’ kangaroo rats (SKR), Dipodomys stephensi, and to assess their responses to translocation. To do this a combination of behavioural and physiological measures were used. Personality types were identified using quantitative and qualitative measures from mirror-image stimulation and predator scent tests done while animals were held before release (Chapters 3 and 5). A radioimmunoassay specific for cortisol in SKR fecal extract was developed and adrenocortical activity (cortisol) in response to predator urine was reliably assessed in fecal samples (Chapter 2). Fecal cortisol concentration (FCC) was used to measure the effect of translocation stressors, including the use of radio transmitters (Chapters 4 and 5). Survival was affected by individual variation in behavioural and physiological responses (Chapter 5). Assertiveness, Excitability and Persistence were identified as three personality dimensions. Overall, FCC increased in response to temporary captivity. Radio transmitters caused a short-term elevation in FCC 6 days after attachment but not at 30 days. Survival to 1 month was similar for animals with and without transmitters. SKR with lower Assertiveness and Excitability and with higher basal FCC had higher short-term survival. Higher Assertiveness was correlated with lower basal FCC. SKR that had a smaller change in FCC during captivity had higher long-term survival. This study lends convincing support that variation in personality affects how well an animal copes with translocation and has consequences for survival. Knowing how to manage different personality types may determine how successfully a translocated population establishes itself.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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