Natural factors
Natural factors include natural variability in numbers, predators, and competition (described below) and also diseases, parasites, and fire, which are described more fully under the climate change section.
Natural Variability
There are natural variations in the numbers of caribou. This variability is thought to run in cycles, and to be influenced by the overgrazing of habitat when populations are at their peak. Traditional knowledge holders in the NWT have put the cycles of barren-ground caribou at between 10 and 60 years. Scientific studies agree that the population cycles seem to run over several decades.
This variability is not a threat to caribou all by itself, but natural variability can produce low numbers in any given herd or location, and then the low numbers may be driven even lower by other threat factors, making it harder for the caribou to rebound. The rate of change of caribou herds can be steep. For instance, the George River and Leaf River herds increase or decrease at rates of up to 15% a year. That means a herd can double in less than ten years - or its numbers can be halved.
Predators
Wolves are the main predators on the caribou populations of the Canadian Arctic. One three-year NWT study found that in three-quarters of wolves sampled, about two-thirds of their stomach contents were from caribou. Grizzly bears are another major predator, and in some cases depend heavily on caribou for their diet. They not only kill caribou, but also scavenge caribou killed by wolves or hunters. Black bears, lynx, wolverines, and even golden eagles are also among animals that will attack and eat full-grown caribou or calves. There are concerns that as other animals (such as moose and deer) move into caribou territory, they can maintain higher populations of caribou predators.
Competition
There are different views as to how much caribou compete with other animals for food sources, and whether this competition would affect the numbers of caribou, or their choice of range. According to some Indigenous knowledge sources, the presence of muskoxen in an area can reduce food available to caribou. Some Indigenous people believe that caribou do not even like the smell of muskoxen. Some scientific sources also suggest that muskox densities in some places may be detrimental to caribou because of an overlap in what they eat. There is also the potential for more overlap between northern caribou and white-tailed deer and moose. Climate change has allowed these species to expand their range, and they could be competing for some of the same food, and could also introduce new diseases to caribou.
Related news
OPINION: Alaska’s game management goals for Mulchatna caribou are unrealistic
State wildlife officials trying to revive Southwest Alaska caribou killed almost 100 brown bears in less than a month
University of Saskatchewan researchers intensify efforts to track disease in caribou
ARE MIGRATING CARIBOU LOSING THE COLLECTIVE MEMORY THEY RELY ON TO SURVIVE?
Transplanting lichen to grow food for threatened caribou
Can beavers catch chronic wasting disease?
Tłı̨chǫ Gov't says caribou herds need 'balance' between conservation, harvesting, industry
Caribou cams give insight into secret lives
Manitoba responding to first case of chronic wasting disease
Study on Yukon Southern Lakes wolves a 'success story,' researcher says
NWT ENR asks hunters for moose heads
Highly Contagious Bacteria Infects Mulchatna Caribou Herd
Habitat restoration may be alternative to wolf cull, says study
The delicate art of stabilizing Yukon’s Fortymile caribou herd
N.W.T. wolf cull 'inhumane and unnecessary,' says Łutsel K'e Dene First Nation
N.W.T. harvesters will get more training to kill wolves, help caribou population
Researchers watching the balance between Nunavik’s wolves and caribou
Tlicho, N.W.T. govt's submit joint wolf management plan to support caribou recovery
Where are the wolves? Satellite collaring planned for wolves on caribou winter range
Communities 'supporting each other' to conserve Bluenose East herd
Killing wolves won't save caribou herds, experts say
Is Warming Bringing a Wave of New Diseases to Arctic Wildlife?
Starvation after weather event killed caribou on remote Arctic island
Related resources
Wolf culls change hunting habits and help caribou conservation
Behaviour is more important than thermal performance for an Arctic host–parasite system under climate change
Usage: Non-commercial with attribution Format: web
Barren-groundBathurstClimate changeNatural factorsGovernment of Canada invests $3.8 million to support barrenground caribou conservation in the Northwest Territories
Usage: Non-commercial with attribution Format: web
Barren-groundRange managementClimate changeHuman disturbanceNatural factorsThe importance of ranges and habitat for the Porcupine Caribou Herd
Usage: Non-commercial with attribution Format: web
PorcupineBarren-groundRange managementNatural factorsUpdate on the global status of wild reindeer and caribou
Usage: Non-commercial with attribution Format: web
PorcupineBarren-groundPearyGeorge RiverRange managementClimate changeHuman disturbanceNatural factorsCaribou gut parasites indirectly create a greener tundra
Usage: Non-commercial with attribution Format: web
Natural factorsReasons for Decisions Related to a Joint Proposal for Dìga (Wolf) Management in Wek’èezhìı
Usage: Non-commercial with attribution Format: web
BathurstBluenose EastManaging predatorsNatural factorsVideo of polar bear hunting an adult caribou
Usage: Non-commercial with attribution Format: video
Natural factorsMUSKOX AND CARIBOU HEALTH MONITORING PROGRAM - activity update June 2021
Usage: Non-commercial with attribution Format: web
Barren-groundBluenose EastDolphin and UnionNatural factorsCaribou and reindeer migrations in the changing Arctic
Usage: Non-commercial with attribution Format: web
Barren-groundRange managementClimate changeHuman disturbanceNatural factorsLarge‐scale prion protein genotyping in Canadian caribou populations and potential impact on chronic wasting disease susceptibility
Aerial Survey of Muskoxen (Ovibos moschatus) and Peary Caribou (Rangifer tarandus pearyi) on Northwest Victoria Island, April-May 2015
Wolves Hunt Caribou In Quebec’s Northern Forest
Format: video
Natural factorsWolf Technical Feasibility Assessment: Options for Managing Wolves on the Range of the Bathurst Barren-ground Caribou Herd
Demography of an increasing caribou herd with restricted wolf control: Caribou Demography and Wolves
Peary Caribou and Muskox Survey of the Melville-Prince Patrick Complex, Northwest Territories and Nunavut Summer 2012
Technical Report on Cape Bathurst, Bluenose-West and Bluenose-East Caribou Herds
Usage: Non-commercial with attribution Format: pdf
Bluenose WestBluenose EastCape BathurstManaging huntingManaging predatorsRange managementClimate changeHuman disturbanceNatural factorsHuntingAerial Survey of Peary Caribou and Muskoxen on Banks Island, July 2014
Weather-based Indices of Parasitic Fly Activity and Abundance for the Bathurst Caribou Post-calving and Summer Range: Users Guide
Engaging Bluenose Caribou Communities
Usage: Non-commercial with attribution Format: pdf
Bluenose WestBluenose EastManaging huntingManaging predatorsRange managementClimate changeHuman disturbanceNatural factorsHuntingWorking together for Baffin Island Caribou
Usage: Non-commercial with attribution Format: pdf
Barren-groundBaffin IslandManaging huntingManaging predatorsRange managementPeopleClimate changeHuman disturbanceNatural factorsHunting