SOUTHERN MOUNTAIN CARIBOU
Mountain caribou’s survival depends on large tracts of undisturbed old growth forest
in the inland temperate rainforest of British Columbia.
Old growth forests in BC's inland temperate rainforest are where mountain caribou thrive in the refugia provided by these vast and dynamic forests. Large and continuous old growth rainforests feed caribou and also allow for caribou spacing mechanisms to occur - such as elevational migrations (moving up and down mountains), and spreading out over large areas to reduce encounters with other wildlife. An intact rainforest allows caribou to hide and span out to avoid predators that also live here, including wolves, cougars, bears, and wolverines. Spacing mechanisms also enable caribou to avoid other ungulates (deer, elk, moose) which could potentially transfer disease or parasites.
Life History
During late winter, mountain caribou feed almost exclusively on tree lichens (lectoria and bryoria spp.) that grow only in old growth habitat within the inland rainforest. Mountain caribou use their large hooves that act like ‘snowshoes’ to reach tree lichens that are high in the air – their ‘snowshoes’ allow them to travel on top of a deep snowpack. Other smaller-hooved ungulates (deer, elk, moose and goats) cannot survive on lichen alone, and cannot reach high elevation lichens in winter due to the deep snowpack. Deeper snow at high elevations also discourages predators from travel, who often use valley bottoms in winter where travel is easier and other ungulate prey remains.
Due to the changing snowpack throughout the changing seasons, mountain caribou herds migrate up and down the mountains (altitudinal migration). They go through this annual migration in order to forage and to avoid becoming a meal for predators, but also to access suitable calving grounds and to escape bothersome insects. Over millennia, mountain caribou have evolved survival strategies to access food, tolerate extreme cold weather, and avoid predators and other ungulates.
In undisturbed inland rainforest habitat, mountain caribou typically maintain a distance away from predators and other ungulates. The separation from other ungulates and predators has enabled mountain caribou to avoid not only predation, but also to minimize the risks of disease transfer (e.g., chronic wasting disease) and parasites. However, clear-cuts in forests, roads, seismic lines, and habitat conversion have compromised the well- evolved avoidance strategies that have kept mountain caribou healthy for thousands of years. Caribou are also sensitive to disturbance (e.g., noise) making them easy to displace. Although southern mountain caribou have lived and ranged in this area for close to 10,000 years, they are now considered endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
This map shows the historical and 2014 distribution of southern mountain caribou. Do you notice how their home range is the same as the distribution of the inland temperate rainforest? The outlined area on the map shows the historical range of southern mountain caribou, which has been greatly reduced. As the forest is destroyed, caribou herds become fragmented and isolated from each other. This means that migration for gene flow and climate adaption is cut off. The patches of old forest that remain are considered by many ecologists as "Islands of Extinction".
"The distribution of mountain caribou is so closely associated with the interior wetbelt in BC that they have been considered a flagship species for this area, and an indicator of the health of the ecosystem."
The largest factor contributing to the population decline of mountain caribou is the destruction, fragmentation and impoverishment of their habitat; the old growth forests in the inland rainforest. While forest fires do account for some of the habitat destruction, the real culprit has been shown over decades by many scientists to be intensive logging. Herds continue to be extirpated in BC while the clear-cut logging continues in critical habitat for mountain caribou. The impacts clear-cut logging has had on mountain caribou can no longer be ignored, disregarded or deferred.
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See scientific publication: Witnessing extinction – Cumulative impacts across landscapes and the
future loss of an evolutionarily significant unit of woodland caribou in Canada.
Clear-cut logging destroys caribou habitat directly. New roads, cut blocks, and backcountry recreation are larger problems for mountain caribou than they first appear, because these practices create snow-packed pathways that lead predators into caribou habitat that could not have been previously accessed. After landscape disturbances (clear-cuts, roads, etc.) the following happens to mountain caribou:
1. They lose their primary food source, tree lichens found in old growth forest that grow extremely slowly.
2. Herds become fragmented so individuals cannot travel back and forth to breed. Caribou avoid moving into
open areas because it exposes them to predators and they become vulnerable without cover to hide in.
3. Shrubs and small plants begin to grow after an area is clear-cut or burned. This is known as early seral growth,
which attracts moose, elk, and deer. Predators are attracted to those ungulates and predate on them all,
including mountain caribou.
4. Fragmented habitat means that more caribou are restricted into smaller areas, making it easier for wolves and
other carnivores to hunt them. Mountain caribou can no longer use the predator avoidance strategies that they
have evolved over millennia.
The conservation dilemma of working to recover caribou populations has led to another serious environmental and ethical problem, namely killing wolves, cougars (mountain lions), bears and ungulate species (referred to as ‘primary prey’). Please read more on this below.
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See media report: Immediate action needed as habitat loss, not wolves, drive caribou to extinction.
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See scientific publication: Habitat loss accelerates for the endangered woodland caribou in western Canada.
Government Sanctioned 'Predator Reduction' Program
The main reason for mountain caribou population declines has been well-known and reported by scientists for decades. It is logging and destruction of their primary habitat, which continues to this day. However, the provincial government continues to authorize the destruction of known high value mountain caribou habitat. Clear-cut logging and the creation of new roads also exacerbates predation rates on caribou (see section above).
Despite decades of recommendations from scientists, BC continues to allow extensive logging in areas that are important for caribou survival, including federally defined core and critical habitat areas needed for mountain caribou recovery.[1] We believe that if we are serious about having mountain caribou in the future, it will be unlikely that all socio-economic implications of recovery measures for this species can be accommodated.
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See scientific publication: No statistical support for wolf control and maternal penning as conservation measures for endangered mountain caribou
Although herds of mountain caribou went extinct in recent years (e.g., Kinbasket herd, Purcell’s South herd), there are still no range plans in place for the remaining caribou herds. These plans, which should address unique problems facing each herd, are long overdue.
When caribou habitat is fragmented by roads, clear-cuts and seismic lines, their evolutionary anti-predator strategy becomes compromised. Conservation groups point out that killing wolves, cougars and other species, creates a public distraction from what is needed most for mountain caribou recovery, which is maintaining large and unfragmented tracts of old growth inland rainforest.
As mountain caribou habitat continues to be logged, moose that move into these areas are also killed through liberalized human hunting. Wolves that follow moose into these areas are shot from helicopters by government contractors. More than 1,000 wolves have been shot and killed in B.C. from helicopters since 2015 through the mountain caribou ‘predator reduction’ program. There has also been extensive hunting of cougars through government-hired contractors who ground hunt using hounds. Simultaneously, other ungulate species are also facing increased hunting pressures from regulations aiming to decrease their numbers so that there is less available food for predators. How long this 'predator reduction' program will continue is unknown.
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See scientific publication: Maintaining ethical standards during conservation crises.
Long-term and wide scale killing of large carnivores can cause ecosystem-wide adverse ecological effects. For instance, by allowing predators to remain on the landscape, they help maintain ungulate health by removing diseased animals and also by limiting disease build-up and transfer by keeping them moving across the landscape to avoid predation. The smaller herd sizes and continuous movement reduces grazing and browsing pressure on plants, allowing for more plant diversity and increased growth rates, which in turn benefits a variety of species of insects, songbirds, fish, amphibians, and mammals. Where wolf populations have been extirpated in North America, a cascade effect is observed in which small mammals, fish, insects, birds, amphibians, ungulates, tree species and vegetation all suffer (e.g., Banff National Park, Yellowstone National Park). Wildlife management policies based on reducing carnivore numbers have caused, and will continue to cause, severe harm to many other organisms that seem distantly removed from the apex (top) predators like wolves. Many things are connected.
To see an example of a wolf trophic cascade, please watch this video: How Wolves Change Rivers.
Even if the ‘predator reduction’ strategy were guaranteed to work, killing one species to save another is highly contentious. Tax-funded predator removal programs are highly controversial for ethical reasons, but also due to the high ecological costs and the questionable science involved. Do the majority of people in BC want their tax dollars to go towards killing predators, especially when clear-cut logging in critical and core mountain caribou habitat is still allowed to continue in BC?
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See scientific publication: Wildlife conservation and animal welfare -Two sides of the same coin?
[1] Ref: Environment Canada. 2014. Recovery Strategy for the Woodland Caribou, Southern Mountain population (Rangifer tarandus caribou) in Canada. Species at Risk Act Recovery Strategy Series. Environment Canada, Ottawa. viii + 103 pp
