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Tim Carpenter 1,2 , Joshua O‘Brien 2 , Clint McCarthy 3 Vic Coggins 4

A Spatial Risk Assessment of Bighorn Sheep Extirpation by Grazing Domestic Sheep in Public. Tim Carpenter 1,2 , Joshua O‘Brien 2 , Clint McCarthy 3 Vic Coggins 4 1 EpiCentre (Infectious Disease Reserach Centre) 2 Center for Animal Disease Modeling and Surveillance

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Tim Carpenter 1,2 , Joshua O‘Brien 2 , Clint McCarthy 3 Vic Coggins 4

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  1. A Spatial Risk Assessment of Bighorn Sheep Extirpation by Grazing Domestic Sheep in Public Tim Carpenter1,2, Joshua O‘Brien2, Clint McCarthy3 Vic Coggins4 1EpiCentre (Infectious Disease Reserach Centre) 2Center for Animal Disease Modeling and Surveillance 3Intermountain Region, US Forest Service 4Oregon Department of Fish and Wildlife

  2. Payette National Forest, Idaho

  3. Bighorn sheep distribution and abundance • Early 19th century: • 1.5 – 2.0 million animals • 19th & early 20th century: • Habitat loss • Overhunting • Forage competition by domestic livestock • Disease Buechner, Wildlife Monographs (1960)

  4. Bighorn sheep distribution and abundance • 1960: • 15,000 - 20,000 animals • At present: • 57,000 animals • < 4% historic numbers • < 20% historic range • Why have bighorn populations remained depressed? Buechner, Wildlife Monographs (1960)

  5. Disease: population impacts • Bighorns are ‘exquisitely sensitive’ to pasteurellosis. • All-ages die-off: • 33% - 75% mortality in Hells Canyon die-offs. • Poor lamb recruitment: • 25% - 100% mortality • Up to 10 years post-outbreak

  6. Disease: transmission from domestic sheep • Evidence of transmission: • Inoculation experiments • Commingling experiments • Field observations • Studies of ecological correlates of dieoffs

  7. National Forest System Lands • and BHS Occupied Habitat

  8. Payette National Forest, Idaho

  9. Materials and Methods • Telemetry data collected by: • IDFG, WDFW, ODFW, USFS, BLM, Private cooperators, & Nez Perce Tribe. • CHHR, foray and habitat analyses • Historic data • Mapping (ArcGIS) • Models • Contact risk • Disease impact

  10. Core herd home range (CHHR)

  11. Estimating relative foray and allotment contact probability

  12. BHS population and disease modeling • Demographic inputs • Initial herd population sizes • Population growth • Epidemiologic inputs • Initial herd infection status • Herd-to-herd contact probabilities • BHS-to-BHS transmission • DS-to-BHS transmission • Effective contact probability • Disease outbreak impact • Extended infectious duration • Extended adverse effect impact

  13. Analyze a little data…

  14. Create a model…

  15. Keep building the model… Initial herd population-level and infection parameters. Model parameters and sample values for disease spread. Model parameters and sample values for disease impacts.

  16. Evaluate the available alternatives …

  17. Evaluate more alternatives …

  18. Present the final results to • the decision maker and watch!

  19. Present variability results to • the decision maker and explain!

  20. Conclusions • GIS/Mapping, spatial, epidemic modeling, and risk assessment are valuable tools for decision makers, forced to deal with the livestock-wildlife interface. • However, this value may be overestimated (given the amount of uncertainty) and these limitations should be conveyed. • The PNF modeling approach is currently being used by other western land managers to determine the future of USFS sheep allotments. • Wool Growers vs. USFS – 100 Gbytes; >10,000 pages and 37DVDs (DoJ)

  21. Acknowledgements • USFS (Chans O’Brien, Tim Schommer, Pattie Soucek, Melanie Woolever) • Working group convened by the PNF that included BHS biologists, wildlife disease experts, and representatives from five US National Forests, the Intermountain Regional Office of the US Forest Service, three state fish and wildlife agencies, four Native American Tribes and representative from the ID Office of the Governor. T.E.Carpenter@massey.ac.nz

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