Sheep Vegetation Management Guidelines

Appendix 2. Potential Domestic Sheep Impacts on Wildlife and Wildlife Habitat

The evaluation of sites for their suitability for vegetation management using domestic sheep includes the regional MELP Wildlife and Habitat staff assessment of potential impacts of the domestic sheep and the projects on:

  • wildlife species and wildlife habitat, through the removal of vegetation and displacement of animals;

  • wild carnivore populations, through temporary displacement of carnivores, conflict with humans and predation on sheep; and

  • wild ungulate populations, particularly bighorn and thinhorn sheep and mountain goats, through disease and parasite transmission.

Well managed vegetation management projects using domestic sheep are unlikely to create severe impacts under any of the above categories, however, potential risks to the environment do exist and must be managed.

Regional Environment staff should consult with the proponent, and, if required, other MELP wildlife and habitat biologists, Species Specialists and the Wildlife Health Veterinarian, the Ministry of Agriculture Animal Health Veterinarian, representatives of the B.C. Sheep Federation, sheep contractor groups and other professionals. Project sites may be considered unacceptable if the risks associated with one or all of the impacts are determined to be too high.

Wildlife and wildlife habitat

The removal of vegetation by domestic sheep can impact wildlife species that utilize low lying plants and shrubs or specific areas for food, nesting and shelter. Some species may be displaced to nearby sites without significant effects, but others may lack the ability to move or adaptability to survive in new sites. The use of domestic sheep for vegetation management is not recommended where:

  • affected wildlife populations are rare or threatened, or

  • affected wildlife habitats are considered unique or sensitive (critical ranges), and

  • the disturbance by vegetation management using domestic sheep is considered to threaten either the species or their habitats.

Examples include sensitive riparian areas or identified breeding areas of certain species. Opportunity to protect affected wildlife may be provided through appropriate grazing management that would consider altering the period of use or grazing seasons to accommodate the needs of species during critical times such as nesting and breeding.

Carnivore Interactions

A carnivore is defined as a grizzly bear, black bear, bobcat, lynx, cougar, wolf, coyote, wolverine, bald or golden eagle. Grizzly and black bears are of special concern due to the status of the grizzly bear, the potential danger to humans and the difficulty of remedial actions. The potential impacts to wild carnivore populations by vegetation management projects using domestic sheep and the humans involved include:

  • temporary displacement from normal ranges,

  • changes in carnivore behaviour due to the availability of vulnerable prey, may result in predation on domestic sheep, and conflict with humans. Carnivores may continue the predation behaviour or interact with humans associated with the project, potentially resulting in destruction of the carnivore.

Site conditions may create an increased risk of predation of domestic sheep and conflict with humans if:

  • carnivore density is high or when topography or vegetation cover is favourable to predators,

  • animal behavior, injury or outbreaks of disease predispose domestic sheep to predation, or

When MELP judges that there is a potential for conflict between domestic sheep and resident wild carnivores, wild carnivore conservation will receive the higher priority.

Wildlife Health

There are a number of infectious diseases and parasites, which can be transmitted between domestic and wild animals. Transmission of some organisms occurs through close contact, however, infection of some conditions can occur indirectly through environmental contamination or with intermediate hosts. The effects of disease and parasitic organisms on wild animal populations may be negligible or they can be disastrous, the effects dependent on many factors. Regardless of the effects, once transfer occurs, the control of any disease in wild populations is virtually impossible and very expensive. Therefore, precautionary measures are not only advisable but crucial to avoid impacts.

The Sheep Health Protocol (Appendix 3) was devised to not only prevent disease or parasite transfer from sheep to sheep within the project flock, but also the potential transfer from sheep to wildlife. It ensures that only domestic sheep in good health, capable of the work required, are used for vegetation management projects. The Protocol also ensures that unhealthy sheep with problems predisposing them to predation are not present on project sites.

Unfortunately, it is not possible to detect and treat all infectious diseases and parasites of domestic sheep in live animals, even with strict adherence to the Protocol. Even animals in apparent good health may be infected without symptoms and can shed organisms that may be picked up by wildlife. Although other wild ungulate species can potentially be infected by organisms carried by domestic stock, the bighorn and thinhorn sheep and mountain goat populations are at the highest risk.

There are many examples of disease occurrences and outbreaks caused by organisms shared between these species. Although some literature reports have been circumstantial, the diseases in wild sheep and goats invariably result in high morbidity and mortality and cannot be treated. Separation of the species is the only effective control method. Diseases of potential significance include Psoroptic Mange, Scrapie, Pasteurellosis, Johne's Disease, Epizootic Haemorrhagic Disease, Infectious Footrot, Malignant Catarrhal Fever, Contagious Ecthyma and Contagious Lymphadenitis.

Projects sites must be situated so that:

  • generally, any proximity or physical contact with wild sheep or goat species is avoided.

  • specifically, where the Ministry of Environment determines that the transmission of infectious organisms is a risk to any wild ungulate, a buffer zone to prevent physical contact between wild species and domestic sheep used for vegetation management must be established. The size of the buffer zone should be based on the Ministry of Environment's assessment of site-specific conditions.

When MELP judges that there is a potential for infectious organism transfer between domestic sheep and resident wild ungulates, wild ungulate conservation and health will receive the higher priority.

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