On Sunday and Monday, February 14-15, 2016, USDA Wildlife Services took to the skies and shot the remaining 24 bighorn sheep in the Montana Mountains of northwest Nevada at the request of Nevada Department of Wildlife. These were important sheep because they were once healthy and over 60 had been translocated from there to areas in Nevada and Utah over the years. The disease outbreak was first detected in December when the Nevada Department of Wildlife captured some of the bighorn sheep to test them for disease and collar them for monitoring purposes. They found that the sheep were suffering from an outbreak of polymicrobial pneumonia. Since the discovery of the outbreak, 70% of the sheep had died from the disease so they decided to “depopulate”, i.e. kill, the remaining bighorn sheep in an effort to prevent the spread of the outbreak to nearby herds in Nevada and Oregon.

While the exact source of the disease outbreak is not known, it is not surprising that the bighorn sheep in this area are suffering this fate because there are two domestic sheep grazing allotments – the Bilk Creek allotment and the Wilder-Quinn allotment – in the middle of this area and BLM ignored the disease threat that they pose to bighorn sheep.

In 2012 the BLM began the permit renewal process for one of the allotments – the Bilk Creek allotment – and Western Watersheds Project submitted comments notifying them of our concern about the risk that domestic sheep posed to bighorn sheep in this area. It is well know that domestic sheep are carriers of pathogens that result in deadly pneumonia to bighorn sheep and that even just one nose-to-nose contact between these related species can result in a disease outbreak that commonly kills up to 90% of a herd and kills the offspring of the remaining animals for up to a decade.

In 2013 the BLM issued the Final Environmental Assessment that dismissed those concerns and simply stated:

Bighorn Sheep – A portion of the Bilk Creek Allotment has been identified as potential habitat for bighorn sheep. The allotment falls into the California bighorn sub-species delineation for reintroductions identified in the Nevada Bighorn Sheep Management Plan (NDOW, 2001). The Paradise-Denio Management Framework Plan set the forage allocation for bighorn at 30 AUMs. There are no immediate plans to reintroduce bighorns on the allotment since the allotment has an active domestic sheep grazing permit: therefore, there will be no further discussion of them in this analysis.

Western Watersheds Project appealed the permit renewal and once again asked them to examine the risk of contact between domestic sheep and bighorn sheep with a GIS tool recently developed by the U.S. Forest Service to objectively quantify the risk that a bighorn sheep would come into contact with an allotment. The tool was developed to examine the risk that domestic sheep grazing posed to bighorn sheep on the Payette National Forest and it was made available to various agencies so that they could examine this risk in other areas. Unfortunately, the BLM refused to analyze the risk that domestic sheep pose to bighorn sheep. They argued that “[t]he Bilk Creek Allotment does not contain Occupied or Potential Bighorn Habitat according to the Bureau of Land Management (BLM) 2012 Bighorn Sheep Habitat GIS Layer. This GIS layer was obtained from the Nevada Department of Wildlife (Nevada Department of Wildlife).”

This assertion contradicted the layers I had obtained from Nevada Department of Wildlife and was contrary to maps that the BLM had published just a year before which showed that the Bilk Creek Mountains were occupied bighorn sheep habitat. Even if the Bilk Creek Mountains weren’t occupied by bighorn sheep, it didn’t really matter. There was occupied bighorn sheep habitat identified less than 4 miles away and habitat preference mapping showed high quality habitat connecting the occupied habitat to the Bilk Creek Mountains and allotment. Bighorn sheep routinely make long forays in search of mates and food and they are attracted to closely related domestic sheep. The risk was clearly very high.

When the Payette National Forest made the decision to close 70% of the domestic sheep grazing on the National Forest, it determined that an annual risk of contact of no greater than 4% was acceptable. I have since obtained the GIS tool used to calculate these values and, without running the analysis, but based on my experience with it, the risk of contact here is vastly higher than 4% and likely higher than 50%. For the Wilder-Quinn allotment, the risk of contact is 100% because the allotment overlaps occupied habitat. Keep in mind, the tool only calculates the risk that a bighorn sheep would come into contact with the allotment, not necessarily a domestic sheep on the allotment. That being said, the domestic sheep on the Bilk Creek allotment are permitted to graze from April 1st each year to October 1st. There is plenty of opportunity for the two to intermingle.

And it appears that they did intermingle. Now we have 100 dead bighorn sheep and the potential for more. It’s disheartening when the agency tasked to protect important resources makes such an effort to protect damaging uses of our landscapes over such highly prized wildlife.

The domestic sheep grazing on the Wilder-Quinn allotment poses a much greater risk to bighorn sheep in mountain ranges to the west of the Montana Mountains in both Oregon and Nevada. Unfortunately, the permit was renewed without any NEPA analysis in 2008 and the threat remains. It seems unlikely that anything will be changed before the permit expires in early 2018. Western Watersheds Project will be watching.