Evaluating risks associated with capture and handling of mule deer for individual-based,long-term research |
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Authors: | Tayler N. LaSharr Samantha P. H. Dwinnell Brittany L. Wagler Hall Sawyer Rhiannon P. Jakopak Anna C. Ortega Luke R. Wilde Matthew J. Kauffman Katey S. Huggler Patrick W. Burke Miguel Valdez Patrick Lionberger Douglas G. Brimeyer Brandon Scurlock Jill Randall Rusty C. Kaiser Mark Thonhoff Gary L. Fralick Kevin L. Monteith |
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Affiliation: | 1. Haub School of the Environment and Natural Resources, Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology, University of Wyoming, 804 E Fremont Street, Laramie, WY, 82071 USA;2. Haub School of the Environment and Natural Resources, University of Wyoming, 804 E Fremont Street, Laramie, WY, 82071 USA;3. Western Ecosystems Technology, Inc., 1610 Reynolds Street, Laramie, WY, 82072 USA;4. Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology, University of Wyoming, 804 E Fremont Street, Laramie, WY, 82071 USA;5. U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology, University of Wyoming, 804 E Fremont Street, Laramie, WY, 82071 USA;6. Wyoming Game and Fish Department, 351 Astle Avenue, Green River, WY, 82935 USA;7. Bureau of Land Management, Rock Springs Field Office, 280 US-191, Rock Springs, WY, 82901 USA;8. Wyoming Game and Fish Department, Department Headquarters, 5400 Bishop Boulevard, Cheyenne, WY, 82006 USA;9. Wyoming Game and Fish Department, Pinedale Regional Office, 432 Mill Street, Pinedale, WY, 82941 USA;10. United States Forest Service, Big Piney Ranger District, 10418 South US Highway 189, Big Piney, WY, 83113 USA;11. Bureau of Land Management, Pinedale Field Office, 1625 West Pine Street, Pinedale, WY, 82941 USA;12. Wyoming Game and Fish Department, Jackson Regional Office, 420 North Cache, Jackson, WY, 83001 USA |
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Abstract: | Capture and handling techniques for individual-based, long-term research that tracks the life history of animals by recapturing the same individuals for several years has vastly improved study inferences and our understanding of animal ecology. Yet there are corresponding risks to study animals associated with physical trauma or capture myopathy that can occur during or following capture events. Rarely has empirical evidence existed to guide decisions associated with understanding the magnitude of capture-related risks, how to reduce these risks when possible, and implications for mortality censoring and survival estimates. We used data collected from 2,399 capture events of mule deer (Odocoileus hemionus) via helicopter net-gunning to compare daily survival probabilities within a 10-week period centered on a capture event and evaluated how animal age, nutritional condition (body fat), and various handling methods influenced survival before, during, and following a capture event. Direct mortality resulting from capture efforts was 1.59%. Mean daily survival was 0.9993 ± 0.0001 (SE) during the 5-week pre-capture window, was depressed the day of capture at 0.9841 ± 0.0004, and rebounded to 0.9990 ± 0.0008 during the 5-week post-capture window. Neither capture nor handling had a detectable effect on post-capture survival, including handling time ( = 13.30 ± 1.87 min), capture time of year (i.e., Dec or Mar), tooth extraction, and the number of times an animal had been recaptured (2–17 times). Although mortality rate was slightly elevated during capture (resulting from physical trauma associated with capture), age and nutritional condition did not influence the probability of mortality during a capture event. Following a capture event, nutritional condition influenced survival; however, that relationship was consistent with expected effects of nutritional condition on winter survival and independent of capture and handling. Overall survival rates 5 weeks before capture and 5 weeks after capture were not different. A specified window of time with depressed survival following capture and handling was not evident, which contradicts the implementation of a predetermined window often used by researchers and managers for censoring mortalities that occur after capture. Previous notions that censorship of all mortality data in the 2 weeks following capture is unwarranted and risks removal of meaningful data. With previous evidence guiding our protocols for capture (e.g., reduced chase time) and handling (e.g., temperature mitigation), low direct mortality and almost undetectable indirect mortality post capture reinforces the efficacy of helicopter net-gunning for capture and recapture of mule deer in long-term, individual-based studies. |
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Keywords: | capture myopathy capture techniques censoring daily survival helicopter net-gunning life history mule deer nutritional condition Odocoileus hemionus survival |
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