Dissertation
Stress-mediated and habitat-mediated risk effects of wolves on free-ranging cattle in Washington
Doctor of Philosophy (PhD), Washington State University
01/2019
Handle:
https://hdl.handle.net/2376/112046
Abstract
Wolves (Canis lupus) can affect free-ranging cattle (Bos taurus) through direct consumption or indirectly through risk effects (i.e., the cost of anti-predator behavioral responses). Currently there remain a paucity of studies that investigated how cattle respond to wolf predation risk, therefore in the present research we evaluated both stress-mediated and habitat-mediated risk effects of recolonizing wolves on range cattle in Washington, USA.
First, because traditional measure of stress hormones (fecal glucocorticoids - GCMs), provide inconclusive results when applied on free-living animals, we validated a new methodology to characterize cattle stress response. Conducting a stress-induced experiment on captive Angus beef cows, we compared fecal GCM analysis with the new cutting-edge technology of fecal metabolomics. We found that contrary to GCM concentrations, cattle fecal metabolome changed before and after a stressful event proving that fecal metabolomics is a reliable methodology to assess stress response. Subsequently, to characterize cattle stress response in relation to wolf presence, we collected cattle fecal samples and contrasted the fecal metabolome of cattle herds grazing in areas with low and high wolf use. We found that significant metabolic pathway shifts occurred between livestock herds grazing in areas of low and high wolf-impacted areas, and that this difference was primarily correlated to wolf proximity at the landscape scale but not at an individual scale. Finally, in the same study areas we investigated whether cattle habitat use changed in the presence of wolves to balance the conflicting demands for food and safety. Resource selection functions based on 65 GPS radio-collared cows revealed that contrary to our predictions herds grazing in high wolf-impacted areas did not respond consistently to wolf predation risk with habitat shifts that facilitate encounter avoidance.
We conclude that although we found a weak wolf-effect on cattle habitat use, cattle metabolism changed as function of stress due to the presence of wolves. Therefore, further research is needed to know if heightened risk and related stress response resulted in lower pregnancy rates or calf weaning weights.
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Details
- Title
- Stress-mediated and habitat-mediated risk effects of wolves on free-ranging cattle in Washington
- Creators
- Azzurra Valerio
- Contributors
- Caren Goldberg (Advisor)Dan Thornton (Committee Member)Ryan Long (Committee Member)Luigi Boitani (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 153
- Identifiers
- 99900581817701842
- Language
- English
- Resource Type
- Dissertation