Once They Were Numerous, By Mark Trousdell

Article By Mark Trousdell

Located within the Central Cariboo Region of British Columbia, Canada, at the confluence of the Chilcotin and Fraser Rivers, the Junction Sheep Range Provincial Park (Junction Park) consists of a diverse landscape, rolling grasslands, river valleys, forests, cliffs and hoodoos. The park contains some of the most natural grasslands in the Cariboo-Chilcotin Region, providing critical habitat for 12 blue-listed bird, reptile and mammal species.

More than 30% of species-at-risk in British Columbia occur in grassland habitats, although grasslands cover <1% of the provincial land base.

The Junction Park has plants and animals that exist at the northernmost limit of their distribution. Several vulnerable and threatened species are found within the park, including the California bighorn sheep, prairie falcon, upland sandpiper, rubber boa, and long-billed curlew. Other species found in the area include cougar, black bear, mule deer, grouse, and owls.

Junction Park was formed in 1973 as a Wildlife Reserve consisting of 4,774 hectares and was managed by the Fish and Wildlife Branch. The Park was originally established to protect bighorn sheep and their natural grassland habitat. This area was designated as the Junction Wildlife Management Area in 1987, and was designated a Provincial Park in 1995. Two Biologists, Harold Mitchell and Wes Prediger, were instrumental in the effort to protect Junction Park as a Wildlife Reserve. On March 2nd, 1981 Harold Mitchell, Wes Prediger and Pilot Bert Warttig were killed in a helicopter crash while on a sheep counting expedition. Harold and Wes worked tirelessly to protect Junction Park for California bighorn sheep and their efforts lead to the creation of the Junction Sheep Range Provincial Park. Their effort and dedication to bighorn sheep are honoured with a plaque located on a cairn at the lookout of Junction Park.

ABOVE: Lone conifer surrounded by grassland.

Junction Park protects critical breeding, lambing, and winter range for the once numerous California bighorn sheep, a blue-listed species. The Junction California bighorn sheep herd (Junction Herd) was the source population for 36 transplants between 1952 to 1995. A total of 505 sheep were taken from the Junction Herd to establish and supplement populations within British Columbia and the United States. Of the 505 bighorn sheep transplanted, a total of 339 sheep were sent to Oregon, North Dakota, Washington, Idaho, California and Nevada, while 166 where transplanted within British Columbia.

In 1995 the population of the Junction Herd was estimated to be 425 individuals, however the population declined by over 50% to 200 individuals in 1998 and by 2007 the population had declined to less than 100 bighorn sheep. No transplants from the Junction Herd have occurred since 1995 and the population remains low, at around 150 individuals.

No sheep population with less than 50 individuals has survived for more than 50 years.

Several factors are likely contributing to the reduced populations of the bighorn sheep who roam this vast landscape. Disease transfer from domestic sheep and goats is the single greatest threat to the sustainability and recovery of bighorn sheep populations across North America. Respiratory infections that result in pneumonia are the leading cause of all-age die-offs of bighorn sheep. The most prominent culprit is Mycoplasma ovipneumoniae which has been shown to kill up to 80% of a bighorn sheep herd in the initial outbreak. Domestic sheep and goats commonly carry pathogens without symptoms and pathogens can be transmitted to bighorn sheep upon contact or with proximity to domestic sheep and goats. The Junction Herd decline between 1995 and 1998 was likely the result of respiratory infection and subsequent pneumonia.

Small populations can result in low genetic diversity, which can have a major impact on the viability of offspring and their immune response. Due to the population decline that occurred from 1995 to their all-time low in 2007, the Junction Herd may have been unable recover due to underlying genetic constraints. This hypothesis has yet to be examined and is a significant knowledge gap. A lack of genetic diversity is associated with reduced population growth, reduced adaptive potential to environmental changes and an increase in the risk of extinction.

Fire control and suppresion in grassland areas facilitates tree encroachment into grasslands, which reduces available habitat and increases the effectiveness of predators. A burning program is reportedly being initiated in the park to reduce encroachment, and renew the bunchgrass that bighorn sheep rely on. Encroachment from shrubs and trees into grasslands impacts the quantity and quality of forage, reduces access to escape terrain and restricts traditional movement patterns. Fire suppression not only facilitates forest in-growth, it indirectly leads to higher predation risk due to the increase in stalking cover.

ABOVE: Access to Junction Park is via a dirt road that is only accessible between July 1 and November 30.

Cougars, wolves and coyotes are the main predators for the grassland dwelling bighorn sheep. All three are effective predators and when bighorn sheep wander near forested areas they are in danger. Increased forest encroachment provides cover habitat for stalking predators and can increase the effectiveness of predators, resulting in an increase in predation rates. Rams are more vulnerable to cougar attacks due to reduced peripheral vision (in tighter cover) and poor body condition post-rut. Cougars utilize an ambush hunting strategy and are considered less selective for vulnerable individuals within the population, whereas, wolves target more vulnerable members of the population, like the young, old or weak. The differing hunting strategies can result in different impacts on the bighorn sheep populations. Coyotes have a direct and indirect influence on predation rates, they directly prey on young sheep and scavenge kill sites from cougars, indirectly leading to increased cougar predation.

ABOVE: Forested slopes reduce forage quantity and allow cover for predators.

This historically significant population of California bighorn sheep need help to return to their former glory. Scientific insight will need to shape the conservation initiatives in the years to come. We already know how to solve many of the factors affecting bighorn sheep within Junction Park, however there are some factors that will require further scientific understanding. Junction Park is a special landscape that is increasingly rare in British Columbia, as are the specialist species that rely on functioning grassland ecosystems.

Bighorn sheep are a resilient species and have been shown to readily colonize new areas and expand population size relatively quickly, given favourable conditions. Even though the habitat has been protected, the bighorn sheep population is not increasing. There is a suite of issues associated with limited population recovery including habitat quality and quantity, nutrition, disease, predation pressure, genetic isolation and human impacts. There is no silver bullet to population recovery, and numerous small changes will be needed to make a significant impact.

The Wild Sheep Society of British Columbia is a conservation organization that is dedicated to enhancing and protecting bighorn sheep and bighorn sheep habitat within British Columbia. They financially support research on disease severity and transmission, population dynamics and herd heath and are instrumental in prescribed burns for habitat restoration. The scientific body of knowledge is growing, and scientists and land managers are continuously adapting their practices. The Wild Sheep Society of BC has proven to be a champion for conservation and scientific knowledge regarding bighorn and thinhorn sheep in British Columbia.

The Junction Herd has been the source population for 36 transplants within British Columbia and the Western United States, totaling 505 animals. There are many success stories of transplants and re-introductions throughout bighorn sheep range, many of which Junction sheep were the source stock for, however, the current state of the Junction Herd is nothing to celebrate.

The Junction Herd was once touted as the largest non-migratory California bighorn sheep herd in the world. Times have changed.

The once numerous Junction Herd is struggling, and the immediate solutions have not been identified. The Junction Herd deserves some attention, from scientific research to habitat enhancement and potentially even the addition of new genetics. The road to recovery for the Junction Herd will undoubtedly be long, however the actions taken today are vital for future recovery.

Sheep hunters are the driving force of wild sheep conservation in North America, and luckily sheep hunters are some of the most passionate advocates for wilderness and wildlife. No other group has dedicated more to conserving and restoring wild sheep populations throughout North America. The sheep hunting community will once again be called upon, this time to help restore the historically significant Junction Herd to its former glory. With a long and proven track record, the sheep hunting community will undoubtedly be up to the task.

To learn more about the Wild Sheep Society of BC and their upcoming events and projects or to get involved, visit www.wildsheepsociety.com.

About the Author:

Mark Trousdell is a BC resident hunter and committed conservationist. You can find out more about Mark on his Instagram page @athletes_hunt.

 

Posted by Adam Janke