Biology of Disease Connection

NONCOMMERCIAL DOMESTIC SHEEP THREATS

Farm Flocks and Hobby Animals
In terms of bighorn-domestic sheep disease transmission, most emphasis has been placed on the risk associated with commercial sheep flocks grazing on public lands. However, those flocks are not the only sheep threat to bighorns (Hurley et al. 1999). For instance, in the Sierra Nevada Mountains, “disease threats . . . also are posed by the prevalence of domestic sheep and goats on private land; these include larger flocks on farms, as well as individual animals and smaller flocks in small pastures and back yards. In many cases, non-commercial or hobby animals may pose a greater threat because there may be less awareness by their owners of the risk to bighorn” (USFWS 2007, 111).

penned domestic sheep

During a moderated 1999 discussion (at the 2nd North American Wild Sheep Conference) between biologists regarding bighorn-domestic sheep interaction, Meyer made insightful comments regarding the threat of noncommercial domestic sheep:

“When I drove home [from Whitefish, MT], all the way down the Bitterroot Valley and through Idaho, there were farm flocks all the way from Challis down to Salmon. We’ve lost our bighorn sheep herds in those areas and this winter the bighorns are coming down and interacting with the domestic sheep. We have a problem with that” (Hurley et al. 1999, 285).

Bighorn interaction with noncommercial domestic sheep or goats was also possible during several pneumonia-caused wild sheep die-offs that occurred during the especially fatal winter of 2009-2010. The die-off near Bonner, Montana occurred in a region with domestic sheep and goat farm flocks (WAFWA 2010a).

Before and after the outbreak, known association between bighorns and domestic
sheep or goats occurred (WAFWA 2010b). Edwards et al. explain:

“Numerous domestic sheep and goats were present for many years as hobby flocks and commercial operations, but there had been no previously known incidence of pneumonia in the Bonner population. After the die-off was detected in January 2010, the public reported a case of bighorns and domestics comingling in the fall of 2009” (2010, 33).

A die-off also occurred near Rock Creek, Montana (WAFWA 2010a). Regarding the Rock Creek bighorn range, the Western Association of Fish and Wildlife Agencies’ Wild Sheep Working Group states: “a large [domestic sheep] flock is pastured directly adjacent to the core of the [bighorn] range, with intermingling known to have occurred in the past” (2010a, 1). Additionally, a winter 2009-2010 bighorn die-off occurred in Washington’s Yakima River Canyon, which hosted both 4-H domestic sheep and farm flocks (WAFWA 2010a).

Regarding a bighorn die-off that occurred in Nevada’s East Humboldt Range in the winter of 2009-2010, McAdoo, Wolff, and Cox state:

“Hobby flocks have always existed on private lands at the base of the range. Domestic sheep were used on private land adjacent to the USFS boundary the past 2 summers for fuels management with reports from sportsmen, bighorn tagholders, and permittees that domestic sheep were observed beyond the private land boundary in known summer bighorn use areas in late summer 2009” (2010, 52).

Sheep and Goats for Vegetation Management
Another noncommercial livestock threat to bighorns involves “domestic sheep or goats [used] for weed control or silvicultural practices near wild sheep habitat” (Erickson, Coggins, and Alt 2000, 87). Domestic sheep were used for weed control in the vicinity of the 2009-2010 Bonner die-off. Domestic sheep (likely strays from a group used for “fuels management” on private land near a National Forest boundary) were also observed in East Humboldt Range bighorn habitat in late summer 2009 before that region experienced its 2009-2010 bighorn die-off (WAFWA 2010b).

Additionally on a questionnaire presented to biologists at the 2nd North American Wild Sheep Conference in 1999, North Dakota bighorn manager Mike Oehler states: “Much to our chagrin, there are federal agencies who continue to consider using domestic sheep and goats as a method for controlling noxious weeds in areas in and around our [bighorn] sheep herds” (Arthur et al. 1999, 434). Furthermore, in Montana, the City of Missoula’s decision to control weeds on Mount Jumbo with domestic sheep grazing has led wildlife managers to shoot two young bighorn rams that got too close to domestic sheep (MFWP 2010). Such euthanization is standard procedure (Mack 2008).

REFERENCES
Arthur, Steven M., Ian Hatter, Alasdair Veitch, John Nagy, Jean Carey, Jon T. Jorgenson, Raymond Lee,  John Ellenberger, John Beecham, John J. McCarthy, Gary Schlichtemeier, Larry T. Gilbertson, Bill Dunn, Don Whittaker, Ted A. Benzon, Jim Karpowitz, George Tsukamato, Kevin Hurley, Steven G. Torres, Craig Mortimore, Mike Oehler, Patrick Cummings, Craig Stevenson, Eric Rominger, and Doug Humphreys. 1999. Appendix A: Wild sheep status questionnaires. In proceedings of 2nd North American Wild Sheep Conference, Reno, NV. April 6-9.

Edwards, Victoria L., Jennifer Ramsey, Greg Jourdannais, Ray Vinkey, Michael Thompson, Neil Anderson, Tom Carlsen, and Chris Anderson. 2010. Situational agency response to four bighorn sheep die-offs in western Montana. In proceedings of Northern Wild Sheep and Goat Council’s 17th Biennial Symposium, Hood River, OR. June 7-11.

Erickson, Glenn L. (moderator and panel member), Vic Coggins, and Kurt Alt (panel members). 2000. Designing a protocol: What should you do if you are faced with a bighorn sheep die-off? Working session in proceedings of Northern Wild Sheep and Goat Council’s 12th Biennial Symposium, Whitehorse, YK. May 31-June 4.

Hurley, Kevin (moderator), Jon Jorgenson, Helen Schwantje, Craig Foster, Herb Meyer, Amy Fisher, Dave Hacker, Harley Metz, Jim Karpowitz, Melanie Woolever, Dick Weaver, Tim Schommer, Cal McCluskey, Duncan Gilchrist, Jim Bailey, Bonnie Pritchard, Dave Byington, Dave Smith, Bill Foreyt, and Dave Hunter (discussion members). 1999. Open discussion – Are we effectively reducing interaction between domestic and wild sheep? Discussion in proceedings of 2nd North American Wild Sheep Conference, Reno, NV. April 6-9.

Mack, Kurtis M. 2008.Wandering wild sheep policy: A theoretical review. In proceedings of Northern Wild Sheep and Goat Council’s 16th Biennial Symposium, Midway, UT. April 27-May 1.

McAdoo, Caleb, Peregrine Wolff, and Mike Cox. 2010. Investigation of Nevada’s 2009-2010 East Humboldt Range and Ruby Mountain bighorn dieoff. In proceedings of Northern Wild Sheep and Goat Council’s 17th Biennial Symposium, Hood River, OR. June 7-11.

Montana Department of Fish, Wildlife, and Parks (MFWP). 2010. Montana Bighorn Sheep Conservation Strategy: 2010. Helena. http://fwpiis.mt.gov/content/getItem.aspx?id=3974 6 (accessed October 15, 2011). [govt. doc.]

U.S. Fish and Wildlife Service (USFWS). 2007. Recovery Plan for the Sierra Nevada Bighorn Sheep. Sacramento. http://www.nps.gov/yose/naturescience/loader.cfm?csModule= security/getfile&PageID=382279 (accessed October 15, 2011). [govt. doc.]

Western Association of Fish and Wildlife Agencies (WAFWA). 2010a. Summary on 9 BHS Die-offs in 5 Western States: Winter 2009-10 (June 22, 2010). Cheyenne: WAFWA. http://www.wafwa.org/documents/wswg/Summary9BHSdie-offsin5westernstateswinter 2009-10.pdf (accessed May 17, 2012).

Western Association of Fish and Wildlife Agencies (WAFWA). 2010b. WAFWA Wild Sheep Working Group summary: Winter 2009-2010 bighorn sheep die-offs (3/16/10). Cheyenne: WAFWA. Web address no longer available (accessed August 23, 2010; based on file info).