Maine has only 29 mapped records of the American water shrew, but the state holds something genuinely unusual for this species: shrews living almost at sea level, when most of the species’ confirmed range sits high in mountain streams out west.
A sea-level foothold, rare for the species
Nationally, water shrew records cluster hardest above 6,500 feet in places like Utah, Wyoming, and Nevada, where cold, fast, oxygen-rich mountain streams support the aquatic insect larvae this shrew hunts by touch. Maine’s coastal streams manage the same trick without any elevation at all: cold, clean, quick-moving water draining the state’s granite coastal hills stays oxygenated enough, even down near the shore, to hold the same prey base a shrew would otherwise have to climb a mountain to find.
Small streams inside big coastal refuges
Maine’s records come from Acadia National Park and the Down East refuges of Rachel Carson and Petit Manan, places best known for salt marsh, tidal flats, and offshore islands. The water shrew itself isn’t a creature of the salt marsh; it needs fresh, running water, and what draws it to these refuges is the network of small, cold freshwater streams that cut through them on the way to the coast, not the tidal habitat the refuges are named for.
Status in Maine
USGS NAS doesn’t list the American water shrew as nonindigenous in Maine, and it’s treated as native across its mapped range in the state.
Full species profile
