What If Gone

Species → Caribou (Porcupine herd)

Caribou (Porcupine herd)

Rangifer tarandus

40% global decline over three generations; migratory Arctic…
Extinction risk Vulnerable
Arctic environmentClimate changeMigration
Caribou (Porcupine herd) (Rangifer tarandus)
Photo: Diego Delso, Wikimedia Commons (CC BY-SA 4.0)

What if it disappeared?

Impact Moderate
Several decades (Fennoscandia)

Where fences have excluded reindeer grazing (the same species as caribou, Rangifer tarandus) for decades, the tundra shifts from a productive, grassy state to moss-dominated dwarf-shrub heath, with slowed nutrient cycling and primary production. Without this grazing, the vegetation doesn't stay the same — it drifts toward a different state.

Documented
Detail

Olofsson, J., Stark, S. & Oksanen, L. (2004). Reindeer influence on ecosystem processes in the tundra. Oikos, 105, 386–396.

The study compares fenced plots (no reindeer) to normally grazed plots, some fences dating back nearly 40 years by the time of the survey — a long-term exclusion experiment of the same kind used on African megaherbivores or sea urchins elsewhere in this reference. The results support what the authors call the "keystone herbivore hypothesis": intensive reindeer/caribou grazing can, on its own, tip the tundra from mossy heath to a more productive grassy state — and its removal tips the vegetation the other way.

Over several years

Caribou make up most of the Arctic wolf's diet in several regions, where wolf reproduction is directly regulated by caribou abundance — a caribou disappearance would likely trigger a corresponding decline in the wolf populations most closely dependent on them, though this link hasn't been measured as precisely as the one between wolves and other prey.

Extrapolated
Detail

Extrapolation à partir de la littérature générale sur la dynamique loup-caribou en Arctique (Klaczek et al. 2016, Journal of Wildlife Management ; synthèses sur le loup arctique) et des données de gestion du troupeau de la Porcupine.

One indirect signal of this dependency: across the Porcupine herd's range, the winter of 2024, with no reduction in wolf populations, coincided with a calf recruitment rate that fell to 14% — a sign that the predator-prey relationship there is already closely monitored and managed in the opposite direction (protecting caribou from wolves), not yet documented in the direction this entry is interested in (the effect of caribou on wolves if caribou were to become scarce).

What's missing to confirm it: A study isolating the specific effect of caribou abundance — rather than Arctic ungulates in general — on the demographics and reproduction of the wolves most closely dependent on them has yet to be established.

Documentation

Last verified: August 7, 2026

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