In a global context; Caribou are in majority found in the arctic tundra, mountain tundra and boreal forests of the North. The current global population is estimated to be around 5 million caribou, with a decline that varies with the geography.
The species has a traditional value to many, they are used for food and clothing for most of the northern populations and some communities in Eurasia domesticated caribou 7000 years ago.
Caribou are separated into seven to nine subspecies that are based on geographical areas, behavioural patterns and the ecology of the area. Three of those subspecies are found Canada which are the barren ground and Peary caribou that can be found in the tundra environment, and the woodland caribou that is located in coniferous forests and muskegs. The woodland caribou has been identified as Threatened or Endangered by the Committee on the Status of Endangered Wildlife ( COSEWIC). Within the woodland species, there are three ‘ecotypes’ that have been identified: boreal, northern and mountain woodland caribou. The mountain ecotype is considered by the Provincial Government as Endangered or Threatened, with an estimated population of less than 1,700 in 2002, experiencing a population decline up to 50% or more within the past 10 years.
The different caribou ‘ecotypes’ in which the species is separated into is based on behavioural and ecological characteristic rather than genetics. The various caribou studied at different locations were genetically similar. However, the differences were seen by focusing on their behavioural and ecological characteristics. The focus of the study is mainly on the mountain caribou which are mostly located in the wet forests of central and south-eastern BC and is of great concern.The mountain caribou have probably been in southern BC for more than ten thousand years because of their habitat condition: wet and mountainous terrain. Due to their high habitat conditions, mountain caribou have adapted to the deep snow and rugged elevated terrain and occupy large patches of mature and old forest. During the winter the mountain caribou feed on lichens that hang from branches of older trees. Their large hooves allow them to travel on top of the snowpack. The arboreal lichen is one of the rare food source that is available for caribou in the winter season. The mountain caribou’ strategy to avoid predators is to simply spread out in large elevated areas; many other ungulates will go to lower elevation habitats and the predators will follow down too.
Background
Mountain caribou use to be spread evenly throughout their geographic range. Although nowadays they are dispersed into subpopulations, defined as a group that has very limited interaction with other groups. There have been eighteen subpopulation identified through radio telemetry data and studies show that they do not overlap. There might a higher number of subpopulations that actually have more interaction with each other but that were not monitored.
There are a few biological gaps that are missing from the caribou studies despite the fact that the mountain caribou species is one of the most studied wildlife species in BC. Over the past 10-15 years there have been aerial surveys conducted to assess the population, invest in the mortality causes and estimate population parameters. On a broad geographical scale the mountain caribou can be identified into four different regions where the ecology, population and threats vary: Kootenay, Columbia, Cariboo, North Mountain.
Threats
The mountain caribou population has to deal with four main threats: habitat change, predation, disturbances and climate change. The most natural cause of mortality within the mountain caribou population is predation. The predation issue became a major focus when in the early 1900’s, probably due to gradual growth level in temperatures, the mountain caribou expanded in the lower altitudes of the province and became more accessible to predators. This resulted in the disappearance of mountain caribou from the interior plateau. This situation happened similarly in the southern part of the range. Through indirect and various causes, the mountain caribou changed it’s habit area and was a more visible and accessible food source for predators.
Furthermore, habitat change is also one of the main reasons the mountain caribou population is in decline. Those habitat threats include forest harvesting, fire, human settlement, roads and reservoirs. They have a direct, as well as an indirect effect on the caribou population. Mature and old forests are often removed by forest harvesting and fires. The forests often produce dead structure that is suitable for lichen growth which is a major winter food source for the caribou in winter. Indirectly, the effects of forest harvesting and fire create young forest areas which are beneficial for other ungulates such as deers as browse colonizes the area but decrease the caribou population that was used as protection habitat. There is also the effect other ungulate habitats have on mountain caribou habitat; with this displacement predators are also moving as the ungulates move. Although the mountain caribou species is a primary food source for these predators, they are killed opportunistically when encountered, increasing the decline of the population as the displacement move more into mountain caribou historical range.
Human disturbances such as human settlements, road and highway constructions and reservoirs have also affected the natural mountain caribou habitat, altering the population’s movement and migratory routes and contributing to the fragmentation of their historical range. Motorised disturbances from vehicules also displaces caribou habitat.
The climate change issue is also affecting the mountain caribou’s population. It is difficult to understand how it affects the population and difficult to predict as it depends on a number of complex factors that include changes in seasonal temperatures, precipitations and other natural factors. Climate change could affect habitat and food resource with the proper abundance of resources necessary to the mountain caribou.
Management Direction
One of the main focuses of the resource management is to reduce the predation issue as it is the most direct threat right now affecting the mountain caribou population. There are three ways to establish predator reduction: direct management. The major predators are bears (grizzly and black), cougar, wolf and wolverine. Although, cougars are the main predators in the southernmost population and wolves are in majority found in the north. Bears, of both species, are found throughout the mountain caribou range and wolverine’s attacks are usually rare.
Moreover, as much as direct management of predators seems to be straightforward and the best option, there are some difficulties. The hunting regulations will not be enough to manage the number of predators that is necessary to recover the caribou population, and if no other measures are implemented such as habitat management the direct management measure by hunting will have to be extensive and ongoing. This measure, if ongoing, will bring social issues such as broad-scale kill programs. As the predator’s population decrease there will be no management control over their prey which will increase ungulates population, however, once the predator management control will finish there will be an increase in their population as they will be feeding a lot.
The other option for prey management would be to manage the main predator’s prey, as mountain caribou’s are rare they can not be a primary food source, but they would be killed by predators when the chance occurs. The density of a primary prey population is what defines the increase or decrease of the predator population. Therefore, if the primary prey population is managed directly and maintained to a low population number the predator’s population will hypothetically decrease too. But, this will for a while be damaging for the mountain caribou’s population as they will become the primary source of food until the predator’s population decreases.
The third option to increase caribou population is manage the habitat around their range; render the habitat range for other ungulates so that they can be displaced and create a wider range of caribou habitat. This method can develop silvicultural techniques to reduce shrub cover and other plants and vegetation that is naturally abundant in young forests in order to allow seral forests to grow older. This could reduce primary prey and therefore reduce the presences of predators in caribou habitat range. However, this method will take up to 60 years before it actually has an impact on ungulates but it is seen as the most stable and self sustaining method.
Therefore, each method would be able to be implemented and would work more or less, but they all have also many limiting factors and the best that could be done is to find a middle ground between the three of them.
Another management method would the maintenance and improvement of the mountain caribou habitat. If the current habitat was kept protected and conserved this would reduce the impact recovery areas for the future and provide additional recovery options. This management option will reduce the predation expected to occur if the habitat range was developed by young forests. This would also provide a bigger food source for the caribou to which some subpopulation might recover. Moreover, it would also reduce human impact and threat, especially if roads are closed and rehabilitated. But this alone would not be sufficient for a full population recovery.
Transplantation of females and calves for protection is usually used as a last resort and gravely endangered species should be implemented with other management plans. The problem with transplanted animals is that they will wander outside of the habitat range and will have higher mortality rates.
Conclusion
A scenario management is being established at present; this process is going to establish a model that will show the likelihood of the mountain caribou recovery and focus on the effect that the different management options could have based on the best available information. Once developed, the data will be tested and reviewed by qualified scientists. There has been already a conclusion made about mountain caribou. The conclusion is: if nothing is done to alter the major threats to the mountain caribou population there will be an ongoing decline in the population. The results of the management options will vary throughout the range. Without an increased survival rate of female and calves, recovery will be unlikely. Finally, the recovery will take a while before it starts to achieve a self sustainable population which will also require implementing more than one management plan.
Mountain Caribou in:
- Evergreen Stewardship Plan for Lillooet Sub Region
- Evergreen Stewardship Plan for South Chilcotin Sub Region
- Source Mountain Caribou Science Team. May 2005. Mountain Caribou in British Columbia: A Situation Analysis. Available at : http://www.env.gov.bc.ca/wld/speciesconservation/mc/files/Mountain_Caribou_Situation_Analysis.pdf [Accessed 03/2021].