Whiskey Mountain Bighorn Sheep Predator Control Project
This report is a final report of the Whiskey Mountain Bighorn Sheep Predator Control Project. This project was funded by the Wyoming Chapter of the Foundation for North American Wild Sheep, (Wyoming FNAWS) and the Wyoming Animal Damage Management Board (ADMB).
Whiskey Mountain bighorns have been a crown jewel for Wyoming's wildlife for over 50 years. This sheep herd has been the source for trap/transplant activity and herd establishment throughout Wyoming and 5 other western states. No sheep have been available for transplant since 1995, due to poor herd performance and low recruitment.
This high profile bighorn herd is one of Dubois, Wyoming's main tourist draws. The National Bighorn Sheep Interpretive Center was located in Dubois to highlight this herd, and is successful in tours, bighorn education and public outreach, using Whiskey Mountain Bighorn Sheep herd as its focus. With a population estimated at over 1,450, the Whiskey Mountain bighorn sheep herd unit suffered a die-off in 1991, with several causes being suspected. Historically, major bighorn die-offs are followed by several years of poor lamb recruitment. After five years, the alarm was sounded by the Wyoming Game and Fish Department (WGFD) and the interagency Whiskey Mountain Bighorn Sheep Technical Committee (WMBSTC), proposing "The Whiskey Mountain Lamb Survival Study" to determine why lamb ratios were not rebounding. Wyoming Chapter FNAWS, along with other non-government organizations (NGOs) were asked to help fund this study.
For the next four years, the Wyoming Chapter stepped up to cover the lion's share of the lamb mortality study. In 1998, the second year of the study, analyses led to the possibility of a selenium deficiency causing symptoms similar to white muscle disease (WMD) in domestic sheep. Since that time, bighorn ewes have been supplemented with mineral blocks in an attempt to relieve this deficiency. The Whiskey Mountain Lamb Survival Study brought up lamb health concerns, and additional concerns of elevational summer migration to mineral/salt licks and predation during these movements. These problems were all addressed and solved by increasing selenium/salt in the diet. Four years of providing selenium blocks, while beneficial, has not improved lamb survival and yearling recruitment.
Discussions between Wyoming FNAWS, WGRD, and the WMBSTC have been held in an attempt to get our arms around this lamb recruitment problem. This herd is aging and lamb survival ratios remain in the single digits per 100 ewes. The herd unit objective remains 1,350, with the herd's population estimated at less that half that and declining.
Over the last four years, the Wyoming Chapter negotiated two USFS domestic sheep allotment waivers in the southern Wind River Mountains, across the Continental Divide from areas 9 and 10, spending nearly $50,000 to help minimize the chance of transmission of Pasteurella bacteria to Whiskey Mountain bighorns from domestic sheep. Thirteen years after the 1990-91 die-off, addressing mineral deficiency and possible habitat and disease problems, no improvement in lamb recruitment has occurred.
Two years ago, Wyoming FNAWS started considering ways to address the possibility that this bighorn herd could be in a "predator pit scenario." Reviewing historical literature of bighorn sheep, several authors noted a recurring theme of coyote predation. Hass (1989) considered coyote predation to be a major cause of mortality of bighorn sheep lambs on the Bison Range National Wildlife Refuge in Montana. Fairaizl (1980) wrote that coyote predation was the major cause of death in transplanted sheep herds in North Dakota. Pertinent to this particular herd, Thorns (1979) believed coyotes were the greatest identified cause of natural mortality in his three-year study. Hebert and Harrison (1988) believed predation by coyotes was a major source of lamb mortality in British Columbia, and that predator control was responsible for significant increases in ewe-to-lamb ratios.
The Wyoming Chapter began pushing to improve lamb survival at Whiskey Basin by removal of a portion of the offending coyotes preying on this herd. In spring 2002, USDA APHIS Wildlife Services (WS) was contacted for a cost estimate to conduct coyote control on lands used by the Whiskey Mountain Bighorn Sheep herd. Beginning in 2003, Wyoming FNAWS and the Wyoming Animal Damage Management Board funded a coyote control project to enhance production on the Whiskey Mountain Bighorn Sheep herd as a partial solution to relieve the "predator pit" problem and raise lamb survival, once again giving this historically important bighorn herd a chance to rebound.
The methods used to take the coyotes were traps, calling, decoy dogs, and fixed-wing aircraft. All recovered coyotes' stomach contents were examined and were found to contain 100% big game - either bighorn sheep or deer - no rodents or anything else were found. Wildlife Services Supervisor Merrill Nelson noted a comment from pilot Ted Jenson: "To find coyotes, all we have to do is find sheep and the coyotes will be near." From the very start of the project, our goal was to work on the offending coyotes that live near these sheep herds, not just the number of coyotes taken. In 2004, we also had the airplane crew work the north side of the highway focusing on the Dennison and Black Mountain sheep wintering areas. Much of that funding came from the Dubois Outfitters Association, Sportsmen for Wildlife and Casper SCI. Dubois Game Warden Cole Thompson felt there was a great improvement in lamb survival in this area. In the three-year period, a total of 127 coyotes were removed from the Whiskey Mountain/Dennison Mountain areas. Sixty-eight were taken from Whiskey; 59 were taken from Dennison.
It is also noted that the classification numbers of lamb-to-ewe ratio in the three years of coyote control averaged in the high 20s, doubling the previous 12-year average for the Whiskey Mountain area.
The coyote control is to continue at least one more year on remaining funds from the project.
Whiskey Mountain Bighorn Sheep Predator Control Project
This report is a final report of the Whiskey Mountain Bighorn Sheep Predator Control Project. This project was funded by the Wyoming Chapter of the Foundation for North American Wild Sheep, (Wyoming FNAWS) and the Wyoming Animal Damage Management Board (ADMB).
Whiskey Mountain bighorns have been a crown jewel for Wyoming's wildlife for over 50 years. This sheep herd has been the source for trap/transplant activity and herd establishment throughout Wyoming and 5 other western states. No sheep have been available for transplant since 1995, due to poor herd performance and low recruitment.
This high profile bighorn herd is one of Dubois, Wyoming's main tourist draws. The National Bighorn Sheep Interpretive Center was located in Dubois to highlight this herd, and is successful in tours, bighorn education and public outreach, using Whiskey Mountain Bighorn Sheep herd as its focus. With a population estimated at over 1,450, the Whiskey Mountain bighorn sheep herd unit suffered a die-off in 1991, with several causes being suspected. Historically, major bighorn die-offs are followed by several years of poor lamb recruitment. After five years, the alarm was sounded by the Wyoming Game and Fish Department (WGFD) and the interagency Whiskey Mountain Bighorn Sheep Technical Committee (WMBSTC), proposing "The Whiskey Mountain Lamb Survival Study" to determine why lamb ratios were not rebounding. Wyoming Chapter FNAWS, along with other non-government organizations (NGOs) were asked to help fund this study.
For the next four years, the Wyoming Chapter stepped up to cover the lion's share of the lamb mortality study. In 1998, the second year of the study, analyses led to the possibility of a selenium deficiency causing symptoms similar to white muscle disease (WMD) in domestic sheep. Since that time, bighorn ewes have been supplemented with mineral blocks in an attempt to relieve this deficiency. The Whiskey Mountain Lamb Survival Study brought up lamb health concerns, and additional concerns of elevational summer migration to mineral/salt licks and predation during these movements. These problems were all addressed and solved by increasing selenium/salt in the diet. Four years of providing selenium blocks, while beneficial, has not improved lamb survival and yearling recruitment.
Discussions between Wyoming FNAWS, WGRD, and the WMBSTC have been held in an attempt to get our arms around this lamb recruitment problem. This herd is aging and lamb survival ratios remain in the single digits per 100 ewes. The herd unit objective remains 1,350, with the herd's population estimated at less that half that and declining.
Over the last four years, the Wyoming Chapter negotiated two USFS domestic sheep allotment waivers in the southern Wind River Mountains, across the Continental Divide from areas 9 and 10, spending nearly $50,000 to help minimize the chance of transmission of Pasteurella bacteria to Whiskey Mountain bighorns from domestic sheep. Thirteen years after the 1990-91 die-off, addressing mineral deficiency and possible habitat and disease problems, no improvement in lamb recruitment has occurred.
Two years ago, Wyoming FNAWS started considering ways to address the possibility that this bighorn herd could be in a "predator pit scenario." Reviewing historical literature of bighorn sheep, several authors noted a recurring theme of coyote predation. Hass (1989) considered coyote predation to be a major cause of mortality of bighorn sheep lambs on the Bison Range National Wildlife Refuge in Montana. Fairaizl (1980) wrote that coyote predation was the major cause of death in transplanted sheep herds in North Dakota. Pertinent to this particular herd, Thorns (1979) believed coyotes were the greatest identified cause of natural mortality in his three-year study. Hebert and Harrison (1988) believed predation by coyotes was a major source of lamb mortality in British Columbia, and that predator control was responsible for significant increases in ewe-to-lamb ratios.
The Wyoming Chapter began pushing to improve lamb survival at Whiskey Basin by removal of a portion of the offending coyotes preying on this herd. In spring 2002, USDA APHIS Wildlife Services (WS) was contacted for a cost estimate to conduct coyote control on lands used by the Whiskey Mountain Bighorn Sheep herd. Beginning in 2003, Wyoming FNAWS and the Wyoming Animal Damage Management Board funded a coyote control project to enhance production on the Whiskey Mountain Bighorn Sheep herd as a partial solution to relieve the "predator pit" problem and raise lamb survival, once again giving this historically important bighorn herd a chance to rebound.
The methods used to take the coyotes were traps, calling, decoy dogs, and fixed-wing aircraft. All recovered coyotes' stomach contents were examined and were found to contain 100% big game - either bighorn sheep or deer - no rodents or anything else were found. Wildlife Services Supervisor Merrill Nelson noted a comment from pilot Ted Jenson: "To find coyotes, all we have to do is find sheep and the coyotes will be near." From the very start of the project, our goal was to work on the offending coyotes that live near these sheep herds, not just the number of coyotes taken. In 2004, we also had the airplane crew work the north side of the highway focusing on the Dennison and Black Mountain sheep wintering areas. Much of that funding came from the Dubois Outfitters Association, Sportsmen for Wildlife and Casper SCI. Dubois Game Warden Cole Thompson felt there was a great improvement in lamb survival in this area. In the three-year period, a total of 127 coyotes were removed from the Whiskey Mountain/Dennison Mountain areas. Sixty-eight were taken from Whiskey; 59 were taken from Dennison.
It is also noted that the classification numbers of lamb-to-ewe ratio in the three years of coyote control averaged in the high 20s, doubling the previous 12-year average for the Whiskey Mountain area.
The coyote control is to continue at least one more year on remaining funds from the project.
