Arizona has only 15 records for the western water shrew, and all but one of them come from a single county at the state’s northeastern edge.
The southern edge of a cold-water range
Apache County holds nearly the entire Arizona record set, tracing back to the White Mountains, where cold, spring-fed streams stay cool enough through summer to support this shrew. That’s about as far south and as low in elevation as the species gets; everywhere else in its range, from Utah and Wyoming north into Alaska, it needs the same narrow band of cold running water. Records appear only in the warmer months, when high-country streams are free of ice and observers are more likely to be near them.
A shrew built to dive
Dense, dark fur traps a silvery film of air underwater, and fringed hind feet give it the surface area to paddle and briefly swim. It hunts aquatic insects and other small prey mostly by touch, working wet moss, undercut banks, and shallow water rather than relying on sight. Its fast metabolism means it can’t go long without feeding, so it stays close to cover along the stream edge between hunting trips.
Status in Arizona
NatureServe ranks the western water shrew S1, critically imperiled, in Arizona, and it’s native to the small stretch of the state where it occurs. That rank reflects just how marginal its foothold is here: a handful of cold White Mountains streams at the very southern tip of a range built for much colder, wetter country.
Full species profile
