The Arctic hare (Lepus arcticus) is a species of hare highly adapted to living in the Arctic tundra and other icy biomes. The Arctic hare survives with shortened ears and limbs, a small nose, fat that makes up close to 20% of its body, and a thick coat of fur. It usually digs holes in the ground or under the snow to keep warm and to sleep. Arctic hares look like rabbits but have shorter ears, are taller when standing, and, unlike rabbits, can thrive in extreme cold. They can travel together with many other hares, sometimes huddling with dozens or more, but are usually found alone, sometimes taking more than one partner. The Arctic hare can run up to .
Etymology
The Arctic hare is named for the region in which it was first discovered, the Arctic tundra. Its generic name, Lepus, is borrowed from Latin and refers to hares, rabbits (as inferred from the earlier Hellenistic Greek (levirís), rabbit), and the constellation of the same name. The specific name, arcticus, is also borrowed from Latin, and is more directly derived from the Greek (arktikos), "near the Bear, northern".
In the Cree language, the Arctic hare is named , coming from the words for "large", , and "rabbit", .
Taxonomy and phylogeny
Arctic explorer John Ross described the Arctic hare in 1819.
There are four subspecies of this hare:
- Lepus arcticus arcticus
- Lepus arcticus bangsii
- Lepus arcticus groenlandicus
- Lepus arcticus monstrabilis
According to analysis by Leandro Iraçabal and colleagues in 2024, the Arctic hare's closest relatives are the broom hare (L. castroviejoi), Corsican hare (L. corsicanus), and the Alaskan hare (L. othus). The broom hare and Corsican hare are placed in a clade that is sister to the Arctic hare:
Fossil record and history
Arctic hare fossils are rare prior to the Holocene epoch, with fossils from the Last Glacial Period found in North America (Wisconsin glaciation) and Europe (Würm glaciation). No fossils from before the Holocene have been found in Russia. The Arctic hare persevered in refugia during periods of glaciation, which led to its differentiation from the Alaskan hare as each species was separated in different parts of North America. Evidence of the Arctic hare has been found in Greenland from 7,960 years ago, and it has colonized regions across the Bering Strait at least twice.
Description
The Arctic hare is one of the largest living lagomorphs. Typically, this species measures from long, not counting a tail length of . The body mass of this species is typically between , though large individuals can weigh up to .
Physiology
The Arctic hare has many physiological features that are adaptive to its extreme environment. Despite a 17% - 38% lower than expected basal metabolic rate, the Arctic hare is able to maintain a body temperature comparable to other lagomorphs (38.9 degrees C) because of its low surface area to volume ratio and high insulation. The lowered metabolic rate also allows the Arctic hare to save energy, making it adaptive for its cold and barren habitat.
thumb|left|alt=Hare footprints in snow|Arctic hare footprints on the snow
The white fur of Arctic hares, in addition to their camouflage benefits in the winter, have a high reflectance which may prevent excessive heat gain during the day. When resting, Arctic hares maintain a nearly spherical shape and typically stay in groups, but do not huddle. The opposite is true at higher latitudes in which Arctic hares had smaller body sizes with increased temperature.
In Newfoundland and Southern Labrador, the Arctic hare changes its coat color, moulting and growing new fur, from brown or grey in the summer to white in the winter. This seasonal moulting also enables other Arctic animals, including ermine and ptarmigan, to remain camouflaged as the environment changes. However, the Arctic hares in the far north of Canada, where summer is very short, remain white all year round. Arctic hares feed primarily on woody plants, with arctic willow constituting 95% of their diet year-round. Arctic hare diets are more diverse in summer. Although previously believed to still be primarily willow, dryas, and grasses, recent studies show that their diet becomes dominated by legumes, constituting 70% of their diet in the summer. Gestation period of the Arctic hare is 53 days, so the babies are born around May, June, or July. Young Arctic hares are almost full size by late July (some weeks after birth) and breed for the first time after a year of age.
The Arctic wolf is probably the most successful predator of the Arctic hare, and even young wolves in their first autumn can catch adult hares.
Four groups of parasites have been known to use Arctic hares as a host: protozoans (Eimeria exigua, Eimeria magna, Eimeria perforans, and Eimeria sculpta); nematodes (including Filaria and Oxyuris ambigua); lice (including Haemodipsus lyriocephalus and Haemodipsus setoni) and fleas (including Euhoplopsyllus glacialis and Megabothris groenlandicus).