REGIONAL TRENDS
State bighorn managers filled out wild sheep status questionnaires (Arthur et al. 1999) at the 1999 North American Wild Sheep Conference (co-hosted by the Desert Bighorn Council and Northern Wild Sheep and Goat Council) in Reno, NV. Answers generally illustrate how much various states were addressing bighorn-domestic sheep interaction management at the time. The questionnaires were presented such that particular biologists filled out sheets for each subspecies in their state. Certain trends stand out (Arthur et al. 1999).
For example, of 15 continental U.S. states with bighorns, only two (Nevada and Oregon) addressed domestic sheep or livestock grazing in response to the question: “What do you do to detect, manage, and/or prevent disease (e.g., disease screening at capture)?” However, 10 states listed livestock grazing or domestic sheep as a state-federal relationship challenge. The states that did not list it as a challenge were: California, Nebraska, South Dakota, Texas, and Wyoming (Arthur et al. 1999).
Six states (Colorado, Nevada, North Dakota, Oregon, Washington, and Wyoming) listed livestock grazing or domestic sheep as a significant bighorn limiting factor. However, four states (Idaho, Montana, Nebraska, and Utah) that did not list livestock under the “limiting factors” question mentioned disease (Arthur et al. 1999).
Bighorn populations in nine states experienced disease die-offs within five years before 1999. Disease die-offs within 25 years before 1999 happened in 11 states. Only Arizona, Nebraska, and Texas did not have disease die-offs listed as occurring either five or 25 years before 1999. The private land factor precluding public land grazing in much of Nebraska and Texas could help explain this trend (Arthur et al. 1999). Nebraska also has few bighorns compared to other states, and wild sheep have only been re-established there since 1981 (Toweill and Geist 1999). However, since 1999, Arizona and Nebraska have each experienced at least one disease outbreak (Jansen et al. 2007; Malmberg, Nordeen, and Butterfield 2008).
When comparing the 15 bighorn-hosting states to each other, Montana and Nevada stand out as having an especially high number of disease outbreaks (WAFWA 2010; Byron 2008; Arthur et al. 1999; NDOW 2011; Cummings and Stevenson 1998). For example, in just the winter of 2009-2010, Montana bighorn populations suffered from four different pneumonia outbreaks (WAFWA 2010). Nevada experienced at least three outbreaks from 2007-2010 (NDOW 2011; WAFWA 2010).
According to Utah Division of Wildlife Resources Director Jim Karpowitz: “In a bad year, there may be two or three bighorn die-offs somewhere in the West” (WAFWA 2010). From 1990-2010, Arizona, California, and Nebraska had the fewest outbreaks (Arthur et al. 1999; Jansen et al. 2007; Torres, Bleich and Wehausen 1996; Malmberg, Nordeen, and Butterfield 2008). The Hells Canyon region (with afflicted sub-populations in Idaho, Oregon, and Washington) was the single metapopulation area that experienced the most disease outbreaks from 1990-2010 (Arthur et al. 1999; Cassirer et al. 1996).
The political/administrative climate in Montana helps explain why so many die-offs occurred there. Regarding development of Montana’s first comprehensive bighorn management plan (released in 2010), Person states that “groups already fighting to get domestic sheep off public land complain that the Department of Fish, Wildlife and Park’s [sic] first-ever bighorn sheep conservation strategy keeps woolgrowers in the drivers’ seat when it comes to determining where bighorn sheep can and can’t roam” (2009).
The final 2010 Montana Bighorn Conservation Strategy of The Montana Department of Fish, Wildlife, and Parks states:
“FWP believes that any localized removal, transfer, or conversion of established domestic sheep allotments on public lands for the benefit of bighorns should only come with the willing participation of the producer and land managing agencies. FWP has spent much time listening to all sides of this issue and while it is FWP’s direction to see bighorn sheep populations expand in distribution and numbers, as a wildlife-managing agency FWP readily acknowledges the contribution of livestock producers in providing valuable wildlife habitat and wildlife presence on their private lands” (2010, 3).
This attitude can be partially explained by the fact that Montana state code prohibits transportation of wildlife that could threaten agriculture (MFWP 2010).
Although Montana and Nevada have suffered many recorded disease outbreaks, Idaho has also faced disproportionately severe die-offs. My background research on bighorn disease across the West does not reveal as many specific die-offs occurring in Idaho compared to Montana or Nevada. However, whether well-recorded or not, high levels of death struck Idaho bighorns in the last 20 years. In 1990, about 3,850 Rocky Mountain bighorns roamed Idaho. Nonetheless, pneumonia outbreaks occurred in the 1990s, and by 1998, an estimated 1,700 Rocky Mountain bighorns inhabited the state (IDFG 2010; Toweill and Geist 1999). That decline of over 50% significantly held back bighorn populations (ID WSF 2012).
By 2012, an estimated 1,900 Rocky Mountain bighorns lived in Idaho—representing a nearly static state-wide population (ID WSF). Significant population growth and recovery would be expected for a healthy population. California bighorn decline in Idaho has been less substantial—going from about 1,460 in 1997 to an estimated 1,000 animals in 2012 (IDFG 2010; ID WSF 2012). Lack of emphasis on wild-domestic sheep separation policies and a state-level political climate largely unfavorable to bighorns contributed to Idaho’s dramatic declines (ID WSF 2012).
SUBSPECIES TRENDS
From 1990-2007, Sierra bighorns suffered no documented disease outbreaks (USFWS 2007). Bighorn die-offs often aren’t well-documented, so specific trends can sometimes difficult to detect. However, based on the sources cited at the end of this sentence, from 1990-2010, Rocky Mountain bighorns suffered far more disease outbreaks than the other subspecies. In the same time period, desert bighorns experienced fewer outbreaks than bighorns in the Rockies, and California bighorns suffered even fewer outbreaks than desert bighorns (Arthur et al. 1999; Jansen et al. 2007; Torres, Bleich, and Wehausen 1996; Buchanan 2008; Cassirer et al. 1996; WAFWA 2010a; Byron 2008; Malmberg, Nordeen, and Butterfield 2008; NDOW 2011; Cummings and Stevenson 1998; Ward et al. 1997; Miller et al. 1995; Rominger and Goldstein 2007; ODFW 2003; Merwin and Brundige 2000; Olson et al. 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.
Barker, Rocky. 2011. Battle for bighorns: Conservationists are struggling to protect bighorn sheep on public lands from disease-carrying livestock. National Wildlife, July. http://www. nwf.org/News-and-Magazines/National Wildlife/Animals/Archives/2011/ Battle-for-Bighorns.aspx (accessed January 7, 2012).
Buchanan, Dave. 2008. Bad news for bighorns – Small bighorn sheep herd near Gunnison suffers major losses. The Daily Sentinel. January 6.
Byron, Eve. 2008. Die-off decimates bighorn sheep herd. Helena Independent Record. April 11. http://www.wildsheepfoundation.org/Page.php/News/36/1207026000-1209528000 (accessed December 25, 2011).
Cassirer, E. Frances, Lloyd E. Oldenburg, Victor L. Coggins, Pat Fowler, Karen Rudolph, David L. Hunter, and William J. Foreyt. 1996. Overview and preliminary analysis of a bighorn sheep dieoff, Hells Canyon, 1995-96. In proceedings of Northern Wild Sheep and Goat Council’s 10th Biennial Symposium, Silverthorne, CO, April 29-May 3.
Cummings, Patrick J., and Craig Stevenson. 1998. Status of desert bighorn sheep in Nevada – 1997. In transactions of Desert Bighorn Council’s 42nd Annual Meeting, Las Cruces, NM. April 9-10.
Idaho Department of Fish and Game (IDFG). 2010. Idaho Bighorn Sheep Management Plan: 2010. Boise. http://fishandgame.idaho.gov/public/wildlife/planBighorn.pdf (accessed October 15, 2011). [govt. doc.]
Idaho Wild Sheep Foundation (ID WSF). 2012. Idaho Wild Sheep Foundation Open Letter: The Continued Decline in Idaho’s Bighorn Sheep Populations. http://www.idahowildsheep. org/big_horn_sheep_decline.htm (accessed August 6, 2012).
Jansen, Brian D., Paul R. Krausman, James R. Heffelfinger, Ted H. Noon, and James C. Devos, Jr. 2007. Population dynamics and behavior of bighorn sheep with infectious keratoconjunctivitus. The Journal of Wildlife Management 71, no. 2 (April): 571-575.
Malmberg, Jennifer L., Todd Nordeen, and Chuck Butterfield. 2008. The effects of disease, stress, and distribution on bighorn sheep restoration in Nebraska. In proceedings of Northern Wild Sheep and Goat Council’s 16th Biennial Symposium, Midway, UT. April 27-May 1.
Merwin, Deirdre S., and Gary C. Brundige. 2000. An unusual contagious ecthyma outbreak in Rocky Mountain bighorn sheep. In proceedings of Northern Wild Sheep and Goat Council’s 12th Biennial Symposium, Whitehorse, YK. May 31-June 4.
Miller, Mike (moderator), Walter Boyce, Marie Bulgin, Bill Foreyt, David Hunter, and Terry Spraker (panel members). 1995. Livestock/bighorn sheep disease transmission. Discussion in transactions of Desert Bighorn Council’s 39th Annual Meeting, Alpine, TX. April 5-7.
Montana Department of Fish, Wildlife, and Parks (MFWP). 2010. Montana Bighorn Sheep Conservation Strategy: 2010. Helena. http://fwpiis.mt.gov/content/getItem.aspx?id =397 46 (accessed October 15, 2011). [govt. doc.]
National Wildlife Federation (NWF). 1995. NWF goes to court to help protect Hell’s Canyon bighorns from fatal disease. National Wildlife, May-June.
Nevada Department of Wildlife (NDOW). 2011. Nevada Department of Wildlife: 2010-2011 Big Game Status. Reno, NV. http://ndow.org/about/pubs/reports/2011_bg_status.pdf (accessed May 14, 2012) [govt. doc.]
Olson, Donald D., Justin M. Shannon, Jericho C. Whiting, and Jerran T. Flinders. 2008. History, status, and population structure of California bighorn sheep in Utah. In proceedings of Northern Wild Sheep and Goat Council’s 16th Biennial Symposium, Midway, UT. April 27-May 1.
Oregon Department of Fish and Wildlife (ODFW). 2003. Oregon’s Bighorn Sheep & Rocky Mountain Goat Management Plan: December 2003. Salem. http://www.dfw.state.or.us/ wildlife/management_plans/docs/sgplan_1203.pdf (accessed October 15, 2011). [govt. doc.]
Person, Daniel. 2009. FWP plan spooks woolgrowers. Bozeman Daily Chronicle. August 18. http://www.bozemandailychronicle.com/news/article_8ed64aa6-33b1-5067-9507-0ae209c8 7594.html (accessed January 7, 2012).
Rominger, Eric M., and Elise J. Goldstein. 2007. Status of desert bighorn sheep in New Mexico, 2006. In transactions of Desert Bighorn Council’s 49th Annual Meeting, Las Vegas, NV. April 3-6.
Torres, Steven G., Vernon C. Bleich, and John D. Wehausen. 1996. Status of bighorn sheep in California – 1995. In transactions of Desert Bighorn Council’s 40th Annual Meeting, Holtville, CA. April 10-12.
Toweill, Dale E., and Valerius Geist. 1999. Return of royalty: Wild sheep of North America. Missoula, MT: Boone and Crockett Club and Foundation for North American Wild Sheep.
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.]
Ward, A.C.S., D.L. Hunter, M.D. Jaworski, P.J. Benolkin, M.P. Dobel, J.B. Jeffress, and G.A. Tanner. 1997. Pasteurella spp. in sympatric bighorn and domestic sheep. Journal of Wildlife Diseases 33, no. 3 (July): 544-557.
Western Association of Fish and Wildlife Agencies (WAFWA). 2007. WAFWA Wild Sheep Working Group Initial Subcommittee Recommendations for Domestic Sheep and Goat Management In Wild Sheep Habitat (June 21, 2007). N.p.: WAFWA. Web address no longer available (accessed on April 23, 2009; based on file info).
Western Association of Fish and Wildlife Agencies (WAFWA). 2010. 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).