The insular vole’s entire range in Alaska, and on Earth, is two small islands far out in the Bering Sea: St. Matthew Island and the smaller Hall Island nearby, in the state’s remote Southwest. It doesn’t occur anywhere else in Alaska, on the mainland, or anywhere else in the world, making it one of the most narrowly distributed mammals the state has.
Both islands are treeless, covered in coastal tundra grasses, sedges, and low shrubs, and swept by near-constant Bering Sea wind and fog. The vole evolved without foxes or weasels ever reaching these islands, so owls and jaegers are its main natural threat rather than the ground predators that shape vole behavior elsewhere.
Records fall almost entirely in July and August, and that says more about the islands’ isolation than about the vole itself. St. Matthew has no permanent population and no easy way in, so researchers reach it only during a brief summer weather window. The vole is almost certainly active there year-round, even though hardly anyone is around to record it the rest of the time.
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