Threats

Climate changeHuman disturbanceNatural factorsContaminantsHunting

Reasons for the drop in caribou populations are complicated. There is still some disagreement among scientific and Indigenous experts as to which factors are most important.

Therefore, this section does not try to give definitive answers as to the causes of the herds’ declines, but covers the main theories. It is important to understand that more than one threat operates on a herd at any given time. These cumulative impacts are hard to untangle, and some impacts may be driven by others. For instance, climate change may promote development of parts of a herd’s range which in turn may increase hunting while at the same time insect harassment is increasing, the caribous’ food is changing, and fires are affecting part of the range. Some Indigenous people do not believe the caribou are declining at all. As noted in several documents that contain Indigenous knowledge, some believe that the caribou have moved away, and will return once people are more respectful, or that the caribou have just switched their usual habitat. Data from satellite-collared cows shows that migratory caribou certainly change their migration routes, and have been known to switch herds.

Related news

See the Giant Arctic Mosquitoes That Are Thriving in a Changing Climate

A study found that warming in the Arctic is lenghtening the mosquito season. The study authors say the longer season gives the mosquitoes more time to harass caribou. Caribou seek higher, cooler places to avoid the insects, but those places may have less food for the caribou. This in turn can lead to poorer body condition and increased chances of death for the caribou.
28 April 2026 | ABC News

Management board urges hunters to watch for parasites in harvested caribou

This news story highlights what appears to an increase in the presence in northern caribou of a worm-like parasite, called setaria. one recent report said that 16 of 23 animals harvested had evidence of the parasite. The Beverly and Qamanirjuaq caribou management board is asking hunters to inspect any animal they shoot, and to report if they appear to be infected. The story quotes Dr. Susan Kutz, a parasite specialist at the Faculty of Veterinary Medicine at the University of Calgary, who says the parasites are alarming, but do not pose a risk to human gealth.
30 April 2025 | CBC North

Highly Contagious Bacteria Infects Mulchatna Caribou Herd

This 18'15" interview focuses mostly on the incidence of the disease brucellosis in the Mulchatna caribou herd in Alaska but also touches on other diseases and parasites, and the connection to climate change. The migratory southwest Alaskan herd has suffered declines similar to those seen in much of northern Canada.
23 July 2021 | KYUK (Alaska)

Related resources

bibliography of sources for caribou and wind turbines

This is a bibliography of sources (both academic and grey literature) that discuss the impact of wind turbines on caribou/reindeer. The resources were compiled by Heather Hayne for WWF Canada.
(2022)

Usage: Non-commercial with attribution
Format: pdf

Barren-groundRange managementThreatsClimate changeHuman disturbance

Measurements of cesium in Arctic beluga and caribou before and after the Fukushima accident of 2011

Concern from northern communities following the Fukushima Daiichi nuclear accident of March 2011 has prompted a reassessment of the safety of their traditional foods with respect to radioactivity levels. To this end, a study was conducted to measure the levels of radionuclides in Arctic caribou (Rangifer tarandus) and beluga (Delphinapterus leucas).
(2016)

Usage: Non-commercial with attribution
Format: pdf

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