Woodland caribou populations have undergone severe declines in B.C. since the turn of the 20th century. The Caribou recovery strategy (2014) states that “at the turn of the 20th century, the estimated number of caribou in all of BC was 30,000-40,000 (Spalding 2000). Aboriginal traditional knowledge holders stated that prior to the arrival of Europeans in north-eastern BC, caribou populations were so high that they were described to be “like bugs on the land” (Willson 2014). Historical records and more recent survey information suggest a general declining trend until about the 1940s, followed in some cases by an increase in numbers through to the 1960s, a subsequent decline in the late 1970s, an increase in the mid-late 1990s, and a decline to the present (Bergerud 1978, Stevenson & Hatler 1985, Seip & Cichowski 1996, Spalding 2000, Thomas & Gray 2002).“According to federal designations, the boreal ecotype is classified as threatened, the northern mountain ecotype as special concern, and the central and southern mountain ecotypes as endangered, with eight local population units under imminent threat.^[i] The B.C. Conservation Data Centre (CDC) has identified the northern mountain ecotypes as blue listed (species of special concern), while the boreal and southern mountain ecotypes are red listed (species that are extirpated, endangered or threatened).^[ii]

FORESTS ARE FOOD

The decline of caribou is one of the toughest conservation challenges in North America. In B.C., caribou are facing a crisis due to habitat destruction. Woodland caribou are food specialists; they depend on old-growth forests that provide abundant lichen as their primary food source. However, human activity has destroyed, degraded, and fragmented caribou habitat. Industrial logging, mining, oil and gas extraction, and recreational activities have rendered the land incapable of sustaining caribou populations.

Caribou face overwhelming health stressors as a result of severe nutritional inadequacies and disease stemming from habitat loss.^[iii] As caribou are unable to meet dietary requirements for protein and energy, they exhibit suppressed maternal body fat as well as calf production and growth.^[iv] These widespread health issues make caribou in B.C. susceptible to disease, parasites, and predation.^{[v,[vi],[vii]} Starvation resulting from the destruction of old-growth forests has had a devastating impact on the reproduction, growth, and survival of caribou populations.

HABITAT LOSS COMPOUNDS PREDATION

When old-growth forests are cleared, they are replaced by early seral forests, which consist of more open, early‐successional vegetation and shrubs. This type of open habitat is favoured by moose, elk, and deer, which move into historically caribou habitats as these landscapes are changed by humans. Moose, elk, and deer are the primary prey of wolves, which follow their preferred prey into the altered landscape through linear features such as logging roads, seismic lines, and snow-packed trails. Although primary prey species don’t directly compete with caribou, their abundance creates a secondary pressure on the species by supporting higher wolf populations, which increases wolf-caribou encounters and predation. The interaction is ecologically termed “apparent competition.”^[viii] Wolves don’t normally seek out caribou, but an exposed caribou will suffice as a meal when they are searching for their primary prey. Simply put, caribou become the wolves’ by-catch. Humans are the ultimate cause of these changes in predator-prey dynamics.^[ix]

Wildlife researchers aim to understand the dominant mechanism by which wolf-caribou co-occurrence is facilitated. In addition to the apparent competition hypothesis leading to wolf-caribou spatial overlap, some research shows greater support for the direct effects of linear features on caribou-wolf, co-occurrence (and thereby predation) ^[x],[xi] DeMars and Boutin’s 2018 study demonstrated that networks of linear feature extending throughout areas of bog habitat increased predator selection for bogs, a habitat type typically favoured by boreal caribou for refugia. The use of these linear features by female caribou increased mortality of new-born calves.^[xii] Female caribou with calves did avoid the use of linear features and areas with a high density of linear features, presumably due to predation risk, however the study  found that most caribou were unable to completely avoid exposure to linear features.^[xiii]  The findings illustrate how linear features diminish prey refugia.

Telemetry mapping by the Valhalla Wilderness Society illustrates that radio-collared caribou by Hope Creek in the Central Selkirk herd range prefer mature and old-growth forests rather than clearcuts and young forest (see image below). Logging access roads allow predators to trap caribou in the remnant patches of mature forest, greatly enhancing the success of predators such as wolves while severely diminishing the chances for caribou to escape.

Scientists refer to the human-mediated predation of caribou by wolves as a proximate cause of decline, or a top-down pressure. However, experts are in agreement that the bottom-up forces associated with habitat loss represent the ultimate cause of decline and herd extinction. Human disturbance means caribou have nothing to eat and nowhere to hide. In addition, the cumulative effects from all forms of industrial development,^[xiv] forest fires, the mountain pine beetle, and climate change all increase pressure on woodland caribou.^[xv]

Image: “Caribou have nowhere to hide.” This telemetry map shows the distribution of radio-collared caribou by Hope Creek in the Central Selkirk herd range. The red telemetry markers of collared caribou in this satellite image from Google Earth shows that caribou prefer mature and old-growth forests rather than clearcuts and young forest. See how the red markers are denser in the darker green (older forest) and very scarce in the grey-brown (recently clearcut) areas. Note how all the logging access roads allow predators to trap caribou in the remnant patches of mature forest. This type of habitat destruction greatly enhances the success of predators such as wolves while severely diminishing the chances for prey animals to escape. Image and analysis  courtesy of the Valhalla Wilderness Society.

short term solutions: mitigating predation

Apparent competition and the direct effects of linear features are likely both contributing to increased wolf-caribou overlap in many cases. Regardless of the dominant mechanism leading to caribou-wolf co-occurrence, which may vary by herd range, the altered landscape and access facilitated through  linear features lead to the  decline of caribou populations.  A growing subset of scientific literature is dedicated to solutions that block linear features and restore previous landscapes.^{[xvi],[xvii],[xviii],[xix],[xx],[xxi]}

Functional restoration involves deactivating linear features such as forest service roads and seismic lines to render them impassable. Felling trees across seismic gas line corridors, and creating swales and debris piles are techniques that have been assessed to slow travel by predators on human-created features on the landscape.   It also has the effect of naturally moving wolves’ preferred prey species (moose, elk, deer) away from caribou herds. Refugia for caribou becomes more isolated and secure, and spatial overlap more characteristic of pre-disturbance.  Experiments in functional habitat restoration have shown that by deploying obstacles to disrupt ease of movement on human developments, wolf-caribou encounters were reduced by 85%.^[xxii] Functional habitat restoration offers short-term results while long-term ecological restoration progresses.

Scientists refer to the human-mediated predation by wolves as a proximate cause of decline, or a ‘top-down’ pressure. However, experts are in agreement that the ‘bottom-up’ forces associated with habitat loss represent the ultimate cause of decline and herd extinction.  Regardless, human disturbance means caribou have nothing to eat and nowhere to hide. In addition to the cumulative effects from all forms of industrial development, further cumulative impacts from forest fires, mountain pine beetle, and climate change all add up to exert mounting  pressures on woodland caribou.

Scapegoating Wolves is a “Palliative Measure” Distracting from Habitat Destruction

The B.C. government has yet to adequately address habitat loss. Instead, it has aimed to intensively reduce the population of wolves through aerial gunning and the use of “Judas wolves,” a controversial practice by which individual wolves are collared with GPS trackers to lead contracted aerial shooters back to their packs. However, there is a lack of reliable science to indicate that the reduction of wolves is having a meaningful impact on caribou recovery.^{[xxiv],[xxv],[xxvi]}  Habitat loss has only intensified since the cull began, despite caribou being listed as an at-risk species under federal legislation and provincial commitments to protect critical caribou habitat.^{[xxvii],[xxviii],[xxix],[xxx]}

Federal recovery strategies and management plans for woodland caribou released in 2012 and 2014 specify that undisturbed habitats are necessary to achieve self-sustaining populations. Under the 2002 Canadian Species at Risk Act (SARA), which mandates the protection and recovery of endangered or threatened species and their habitats, the development of action plans is mandatory to specify the approach for achieving critical habitat conservation and recovery objectives over time.

A 2021 study conducted by multiple researchers including lead scientists from Environment and Climate Change Canada evaluated the effectiveness of environmental policy through an analysis of forest cover. Their report demonstrated that the rate of habitat loss is accelerating despite federal policy instruments. Notably, the study showed that loss of caribou habitat in B.C. and Alberta had increased by 262% in the six to seven years after the release of the federal recovery strategies and management plans.^[xxxi] The researchers concluded that federal policy commitments do not necessarily translate to implementation of commitments, in part due to the lack of species-at-risk legislation outside of federal lands.

In general, Canada has been ineffective in recovering caribou habitat and herds due to gaps between listing, recovery planning, and the execution of conservation and restoration. Mariana Nagy‐Reis, the lead author of the study, drew the following conclusions:

“Our findings support the idea that short-term recovery actions such as predator reductions and translocations will likely just delay caribou extinction in the absence of well-considered habitat management.”

“Predator reductions are a palliative measure as caribou populations are prone to returning to decline soon after such actions cease. Further, it is likely that effective predator management would become increasingly difficult, or impossible, as landscape alteration increases.”

“Our study suggests that unless human-related habitat alterations are adequately addressed, the recovery of most woodland caribou populations seems unlikely.” ^{[xxxii],[xxxiii]}

Scientists resoundingly assert that the cumulative impacts to the land must be addressed to achieve self-sustaining caribou populations. Long-term commitments, including reduction in habitat degradation and restoration, are imperative.

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