What If Gone

Species → Norway Lemming

Norway Lemming

Lemmus lemmus

population highly variable from year to year; no meaningful global…
Extinction risk Least Concern
Predator-prey cycleArctic environmentClimate changeKey prey
Norway Lemming (Lemmus lemmus)
Photo: Lakkahillo, Wikimedia Commons (CC BY-SA 3.0)

What if it disappeared?

Impact Moderate
1 year

As soon as a lemming-free year hits — something that already happened regularly during the troughs of the historic cycle — predators that depend on them, notably the Arctic fox and tundra birds of prey, almost immediately switch to a fallback prey: the eggs of ground-nesting birds. This is what the literature calls the alternative prey hypothesis.

Extrapolated
Detail

Extrapolation à partir d'Ims, R.A. et Fuglei, E. (2005). Trophic Interaction Cycles in Tundra Ecosystems and the Impact of Climate Change. BioScience, 55(4), 311–322 — la bascule vers des proies alternatives, documentée pour une année basse au sein du cycle historique, est ici étendue à une disparition complète et durable des lemmings.

The alternative prey hypothesis describes how, in a lemming-poor year, tundra predators shift to other available food sources, particularly the eggs of ground-nesting birds. The historic cycle already provided, every 3 to 5 years, a preview of what a prolonged lemming absence would produce — the difference being that these low years were, until now, followed by a return to abundance.

What's missing to confirm it: No study directly measures predator response to a total, permanent disappearance of lemmings, as opposed to a simple low year within a cycle that then resumes.

10 years

Repeated year after year rather than being a one-off, this shift toward eggs deprives the Norwegian Arctic fox — already critically endangered after decades of historical overhunting — of the bumper years it relied on to breed en masse, slowing its recovery even after decades of legal protection.

Extrapolated
Detail

Extrapolation à partir de Ims, R.A. et Fuglei, E. (2005). Trophic Interaction Cycles in Tundra Ecosystems and the Impact of Climate Change. BioScience, 55(4), 311–322, et de la littérature de conservation sur le renard arctique norvégien.

The decline of the Norwegian Arctic fox is primarily due to decades of overhunting for fur in the 19th and early 20th centuries, long before the dampening of the lemming cycle was documented. The conservation literature cites the dampened cycle as a compounding factor that complicates the species' natural recovery despite decades of legal protection — a compounding factor, not the original cause.

What's missing to confirm it: The precise share attributable to the absence of lemmings, relative to historical overhunting and other factors, in the Norwegian Arctic fox's difficulty recovering naturally despite decades of protection, remains to be quantified.

100 years

At Finse, Norway, the cycle has already been dampened for nearly 40 years, driven directly by more frequent ice layers forming at the base of the snowpack. If this trend holds for a full century, predators that relied on lemming peaks to breed en masse would never get that opportunity again: their reproduction would settle at a durably lower level instead of continuing to swing between boom and lean years.

Extrapolated
Detail

Extrapolation à partir de Kausrud, K., Mysterud, A., Steen, H. et al. (2008). Linking climate change to lemming cycles. Nature, 456, 93–97 — qui documente l'amortissement du cycle sur près de 40 ans à Finse (Norvège) sans en suivre les effets sur un siècle complet.

The study combines nearly 40 years (1970–2007) of rodent and bird density data with field measurements of snowpack condition at Finse, Norway — a real site where the cycle's dampening is already measured over nearly four decades, not an abstract projection. What remains inferential is the continuation of this trend out to a full century.

What's missing to confirm it: No data on predator populations at Finse beyond the forty years covered by the study was found in the sources gathered here.

1000 years

Over a thousand years, the predators most specialized around lemming peaks — Arctic fox, snowy owl — would likely have given way to more generalist predators able to survive without relying on periodic years of abundance. Even if the cycle eventually returned, those specialist predators would no longer hold the same place in the tundra they once did before it vanished.

Hypothesis

Documentation

Last verified: August 16, 2026