As the bighorn/domestic sheep conflict continues to be an issue, I felt it was important to attend the Sheep in Montana – Domestic and Wild – The State of Things and What We Know About Disease symposium which was held in Helena, Montana, in February.
The symposium was sponsored by the Montana Fish, Wildlife and Parks, Montana Wild Sheep Foundation and the Montana Wool Growers Association, and featured presentations from researchers across the West and Canada.
Respiratory diseases in bighorn sheep are both multi-factorial and poly-microbial; and remain poorly understood even under experimental “pen” (enclosure) studies.
Most of the research indicating Mycoplasma ovipneumoniae (Movi) and some strains of pneumonia-associated bacteria may be shared between domestic and bighorn sheep in pen studies in which bighorn sheep and domestic sheep are forced to share the same enclosure. This forced confinement setting would never happen in open range grazing.
Furthermore, Movi and numerous strains of pneumonia-associated bacteria are not only endemic (regularly found) in bighorn herds throughout the West, but can be present in other ungulate species (wild goats, etc); and bighorns can share bacteria amongst themselves. Additionally, Movi and pneumonia-associated bacteria strains are only viable outside the respiratory tract for a few minutes, so require close contact (nose to nose) for transmission. However, shared pathogens do not automatically equate to the development of pneumonia.
The degree of risk of potential transmission of Movi and pneumonia-associated bacteria from domestic sheep to bighorns under open range grazing conditions is unknown. These endemic pathogens can cause bighorn die-offs in the absence of contact from domestic sheep.
While bighorn herds were more numerous in the past, no one has an accurate baseline for population numbers. Even with current methods such as aerial surveys, wildlife biologists are hard-pressed to come up with accurate population numbers, and solely blaming the domestic sheep industry for the demise of bighorns is short-sighted and inaccurate.
The targeted effort to end domestic sheep grazing ignores myriad of other factors that impact bighorns such as predation, nutrition, parasites, population density, habitat, weather, capture myopathy and other stress; and probably the single, biggest factor: inbreeding. It’s a scientific fact that inbreeding creates significant health problems and diminishes resiliency.
Another important issue to point out is the risk analysis model used by the Forest Service on the Payette Forest in Idaho, which ultimately resulted in the removal of 69 percent of the domestic sheep grazing on the forest.
The risk analysis model uses allotment boundaries as a main determination as to whether or not an area is considered high-risk for contact between domestic sheep and bighorns. If a bighorn crossed the allotment boundary, it triggered the high-risk rating.
The model isn’t an assessment of actual physical contact between bighorn and domestic sheep; it’s simply a computer model hypothesizing whether or not a bighorn entered a grazing allotment.
The domestic sheep industry is committed to sound science and research that will help maintain healthy bighorn sheep populations and a sustainable domestic sheep industry.
Eliminating domestic sheep grazing allotments will force many families out of business. That is unfortunate because our ranchers on federal lands contribute greatly to our rural economies while providing food and fiber from natural, renewable resources.
Bonnie Brown is the executive director of the Colorado Wool Growers Association and has been working on grazing issues for the sheep industry since 2000. Reach her at cwgawool@aol.com.
