If you see sick or dead bighorn sheep please contact your local Government of Alberta biologist. For contact information, see:
Bighorn sheep in Alberta
Bighorn sheep are an iconic mountain species. In Alberta, they are the designated Provincial Mammal. Bighorn sheep are highly valued by Indigenous Peoples, Albertans and non-residents for hunting and wildlife viewing.
Rocky Mountain bighorn sheep are one of the rarest hoofed mammals in North America. Alberta, British Columbia and 13 U.S. western states have approximately 40,000 bighorn sheep, less than 10% of their population size in the 1850s.
Alberta has approximately 9,000 bighorn sheep:
- 3,000 in National Parks
- 6,000 on provincial lands.
Some of these sheep also spend time in British Columbia.
Bighorn sheep in Alberta are an important source of disease-free animals to support recovery of wild herds throughout the west.
Bighorn respiratory disease
Bronchopneumonia is a serious respiratory disease associated with large-scale catastrophic die-offs of bighorn sheep throughout North America. Pneumonia occurs when the air sacs (alveoli) in the lungs fill with fluid or pus.
The Western Association of Wildlife Agencies (WAFWA) considers pneumonia the single greatest threat to sustaining wild sheep herds. If a pneumonia outbreak in bighorn sheep occurred in Alberta or B.C., the effects could be catastrophic.
- Since 1937, Alberta recorded six bighorn pneumonia outbreaks, with mortality from 10-75%. Male and female sheep of all ages were affected.
- Since 2010, die-offs occurred in 12 of 15 jurisdictions with bighorn sheep. Alberta, Idaho and New Mexico were the only areas without die-offs.
- Risk evaluations indicate high potential for another pneumonia outbreak in Alberta unless we mitigate and minimize the risks.
- Population recovery after an outbreak often takes 5 to 10 or more years, depending on:
- Number and age of infected bighorns
- Number of chronic carriers in the population (sheep that survive infection and continue to infect others)
- Rate of lamb recruitment. Several years of poor lamb survival can occur after a die-off, particularly if ewes are chronic carriers.
Timeline: History of known die-offs in southwestern Alberta
- Outbreak location: Southern Alberta
- Population before event (rounded to nearest 5): 8500
- Population after die-off (rounded to nearest 5): 2550
- Outbreak location: Highwood Pass
- Population before event (rounded to nearest 5): Unknown
- Population after die-off (rounded to nearest 5): “Significantly less”
- Outbreak location: Sheep River
- Population before event (rounded to nearest 5): 130
- Population after die-off (rounded to nearest 5): 120
- Outbreak location: Yarrow-West Castle
- Population before event (rounded to nearest 5): 400
- Population after die-off (rounded to nearest 5): 100
- Outbreak location: Sheep River
- Population before event (rounded to nearest 5): 175
- Population after die-off (rounded to nearest 5): 105
- Outbreak location: Sheep River
- Population before event (rounded to nearest 5): 105
- Population after die-off (rounded to nearest 5): 80
Causes and transmission
- There are many types of bacteria associated with pneumonia in wild sheep, but the most serious one is a bacterium called Mycoplasma ovipneumoniae (M. ovi).
- M. ovi transfers from infected to healthy sheep or goats by
- Direct physical contact
- Airborne particles up to 30-100m from the source
- M. ovi cannot survive in the environment.
- M. ovi does not infect humans.
Domestic sheep and goats
- Most domestic sheep and goats have a tolerance or immunity to M. ovi and infections go undetected.
- Some domestic sheep and goats exhibit mild signs of pneumonia, ranging from coughing to reduced growth rates.
- Recent testing of domestics finds high occurrence of M. ovi in some flocks in Canada and the US.
- In Alberta, M. ovi testing in domestic sheep and goats is limited and infection rates are unknown.
- Strong scientific evidence indicates increased risk of pneumonia in bighorn sheep following contact with domestic sheep or goats, including a single encounter with an infected domestic sheep or goat.
- The Wildlife Society and the Association of Wildlife Veterinarians believe disease transmission from domestic sheep and goats poses a significant risk to the conservation and restoration of wild sheep populations. Visit the Wildlife Society website at:
- Grazing, weed control and/or vegetation management, and backcountry packing can bring domestic sheep or goats in close proximity to bighorn sheep range in Alberta.
- The Alberta Government generally does not allow domestic goat grazing near bighorn sheep ranges. Domestic goats may be used for back-packing; however, their use for recreation and commercial purposes is not recommended near bighorn range.
Llamas and alpacas
- Llamas and alpacas can carry agents that potentially cause disease in wildlife, although there is no direct evidence that they have been a source of significant disease in wild sheep or goats.
- However, current risk assessments are limited by insufficient data. More research is needed before the risks can be fully understood.
- The Alberta Government encourages actions to minimize potential risk to bighorn sheep from llamas and alpacas:
- Llamas, alpacas and domestic goats can be used as pack animals on most public lands but are prohibited, or require special permission, in some provincial parks (example: wilderness areas, ecological reserves).
- A permit is required for all commercial businesses (example: tours, guided hunting) on public lands, but generally not for recreational activities.
- Near bighorn sheep ranges, the Alberta Government recommends recreation users refrain from using llamas and alpacas.
Other livestock and wildlife
- Although documented die-offs are rare, mountain goats may be at risk of infection from wild sheep, domestic sheep and domestic goats.
- Other domestic species (example: cattle, bison, pigs, horses) do not appear to transmit M. ovi to wild sheep or goats, or vice versa.
- Environmental stressors may increase susceptibility of wild sheep to disease agents. These stressors include:
- High density of wild sheep
- Unhealthy rangeland (example: overgrazing, weeds)
- Mineral deficiencies (example: selenium)
- Harsh weather (example: severe winters, drought)
- Human activities (example: disturbance, habitat loss)
- Stress may partially explain the variation in pneumonia die-off rates among wild sheep herds and the absence or delayed onset of disease following some contacts between domestic and wild sheep.
- The Alberta Government works with wild sheep organizations and industry to reduce stress and disturbance to wildlife. Examples include:
- Habitat enhancement (example: prescribed burns), see the Evan-Thomas 10-year vegetation management strategy 2016-2025
- Standards and guidelines for industrial operators, see the Master schedule of standards and conditions
Bighorn sheep behaviour
Bighorn sheep have several characteristics that may increase disease risk. These include:
- Complex social systems, including
- large social groups that change composition throughout the year
- individual males that move among nursery bands, bachelor groups, and breeding units
- natural attraction to domestic sheep and goats, especially during the breeding season
- Long distance migrations from low to high elevations between winter and summer.
- Exploratory movements by males and females beyond their traditional home ranges.
- Exploration and dispersal of young males (2-4 years old).
- Wandering of older, mature males up to 80 kilometres before and during the rut in search of breeding opportunities.
- Alberta has mapped bighorn sheep ranges at a landscape scale using data from aerial and ground surveys, habitat models, radio-telemetry, and hunter harvest data, as well as local and expert knowledge. To view the range data, see:
- High-risk areas consider bighorn sheep behaviour, landscape features, and proximity to risk factors, as well as potential impacts to stakeholders.
- High-risk areas in other jurisdictions may include lands from 12.5 – 50 km from wild sheep ranges.
- High-risk areas in Alberta are being mapped and will fall within this distance range used in other jurisdictions
Physical separation of wild sheep from domestic sheep and goats is critical to minimize risk of disease transmission. Options to prevent further spread if infection occurs in wild sheep are limited:
- Cull the entire local herd to eliminate the disease agent.
- Test wild sheep repeatedly and kill chronic carriers of M. ovi.
Transplanting sheep from healthy herds may help recover or restore populations in some areas. But only if the original risk factors are eliminated and there are healthy sheep available to transplant.
Alberta is an important source of transplants to the U.S. Maintaining heathy disease-free bighorn sheep in Alberta is vital to both the province and to conservation of herds elsewhere.
Testing procedures are the same for domestic and wild animals. They typically involve nasal and/or tonsil swabs.
Testing has challenges:
- Current tests can be costly.
- Re-testing is necessary to minimize the likelihood of false negatives.
- The many strains of M. ovi limit reliability of one-time tests.
- Research to improve testing is underway, with some early encouraging results.
Alberta is working towards improved testing protocols, interpretation of test results, and current state of research.
Testing Bighorn Sheep
Testing Domestic Sheep and Goats
- Early detection of M. ovi is key to maintaining healthy domestic herds.
- Alberta’s government works with industrial partners to reinforce disease prevention measures and to improve understanding of prevalence of M. ovi in domestic flocks, particularly those used for vegetation management.
- It is important to ensure M. ovi-free domestic sheep and goats in high-risk areas for wild sheep
Vaccines and treatment
- There are no vaccines or treatment for pneumonia in wild sheep. Even if available, administering vaccines or treatments to wild sheep would be challenging.
- There are no treatments to eliminate M. ovi in domestic sheep and goats. However, pneumonia in domestics can be treated with antibiotics.
Minimizing disease risk
Wild sheep enthusiasts and livestock owners share common goals:
- Maintain healthy wild and domestic herds
- Sustain an economically viable domestic industry
- Maintain sustainable harvest and enjoyment of bighorn sheep
Improved collaboration among government, livestock owners, industry, conservation organizations, hunters, researchers and Indigenous Peoples is key to minimizing the risks.
Sightings and strays
Please report the following to your local Government of Alberta biologist:
- Any bighorn sheep near domestic sheep and goats
- Any sick bighorn sheep
- Stray domestic sheep or goats near bighorn sheep ranges
For contact information, see:
Please report all stray livestock to Livestock Investigation Services of Alberta Agriculture and Forestry:
Biosecurity measures minimize the spread of wildlife disease or disease-causing agents, and help ensure healthy and productive domestic herds. Visit the Canadian Food Inspection Agency website at:
In areas near bighorn sheep ranges, “no contact” fencing is recommended when other management strategies are not possible.
To minimize the risk of disease, fencing must:
- Prevent nose-to-nose contact between wild sheep and domestics
- Minimize the likelihood of airborne transmission of disease agents
- Exclude bighorn sheep (they can jump over 2m high)
- Have wire mesh size small enough to exclude lambs.
Livestock guardian dogs may increase the effectiveness of fencing.
Weed and vegetation management
Weeds and competitive vegetation is a concern in various situations in or near areas used by wild sheep. Several methods can effectively control weeds and manage vegetation:
- Domestic sheep or goats
- Herbicides and chemicals
- Insect biological control
- Mechanized or manual removal
The preferred method depends on:
- project objectives
- site location
- target species
- work force
In specific situations, domestic sheep and goats may be more cost-effective, organic or ecologically friendly than other methods such as herbicide application.
For example, in riparian areas, strategies to prevent trampling, erosion and microbial contamination of waterways are important. Disease risks associated with domestic sheep and goats can outweigh the benefits for weed or vegetation management if there is increased probability of a pneumonia outbreak.
Attention weed control and vegetation managers
Do not use domestic sheep and goats for weed control or vegetation management in high-risk areas in Alberta.
Alberta considers separation zones a potential and effective tool to minimize the risk of pneumonia in bighorn sheep on public lands. Separation zones in a sheep context help maintain healthy wild and domestic herds, and sustain an economically viable domestic industry.
Maintaining physical separation between wild sheep and domestic sheep and goats is key to minimizing disease risk. Zoning on public lands can be effective in reducing this risk.
Many jurisdictions with wild sheep use separation zones in association with wild sheep ranges.
How you can help
Commercial and recreational pack animal users
- Do not take domestic goats, llamas and alpacas near bighorn sheep ranges
Domestic sheep and goat owners
- Test for M. ovi
- Report strays in high-risk areas to the local Government of Alberta Biologist. For contact information see Fisheries and Wildlife Management – Contacts
- Use good biosecurity practices and regularly monitor herd health
- Apply no-contact fencing
- Do not use domestic sheep or goats in high-risk areas
Report sightings of bighorn sheep near domestic sheep or goats to the local Government of Alberta Biologist. For contact information, see:
- Have your sheep tested for M. ovi
- Look for sinus tumours
For further details, see:
Weed control and vegetation managers
- Do not use domestic sheep and goats in high-risk areas
- Test for M. ovi
- Use good biosecurity measures and regularly monitor herd health
Film and video
There are over 70 peer-reviewed scientific publications on M.ovi and pneumonia in wild sheep. Below are a few recent references.
Contributing factors (example: density, behaviour)
- A review of hypothesized determinants associated with bighorn sheep (Ovis canadensis) die-offs
- Ecological correlates of pneumonia epizootics in bighorn sheep herds (PDF, 84 KB)
- Spatio-temporal dynamics of pneumonia in bighorn sheep
Exposure history, immunity and chronic carriers
- Epizootic pneumonia of bighorn sheep following experimental exposure to Mycoplasma ovipneumoniae
- Removal of chronic Mycoplasma ovipneumoniae carrier ewes eliminates pneumonia in a bighorn sheep population
- Use of exposure history to identify patterns of immunity to pneumonia in bighorn sheep (Ovis canadensis)
- A review of disease related conflicts between domestic sheep and goats and bighorn sheep (PDF, 442 KB)
- Comparison of wild and domestic sheep interaction policies in bighorn sheep disease outbreak locations in the continental US; 1990-2010
- Recommendations for Domestic Sheep and Goat Management in Wild Sheep Habitat (WAWFA 2012) (PDF, 3.4 MB)
Pneumonia research consortium
Transmission from domestic sheep and goats
- Potential disease agents in domestic goats and relevance to bighorn sheep (Ovis canadensis) management
- Shared Bacterial and Viral Respiratory Agents in Bighorn Sheep, Domestic Sheep and Goats in Montana: Evidence for Strain-Specific Immunity to Pneumonia in Bighorn Sheep
Connect with a local Government of Alberta biologist or Provincial Disease Specialist (Edmonton) for more information about pneumonia in bighorn sheep:
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