The southern half of a split
Until recently, coastal jumping mice from San Francisco Bay north through Washington were all one species, the Pacific jumping mouse. Newer taxonomic work divided that animal, and the Mammal Diversity Database now lists the central and southern coastal populations as Zapus montanus, a name with a long history in the group. The northern Pacific jumping mouse keeps the northern part of the range, centered on Washington.
The two are not separable by casual looks. Both are big-footed, long-tailed mice about 8 to 10 inches from nose to tail tip, with brassy-yellow sides and a darker back stripe. Location draws the line: a jumping mouse from coastal Oregon or California falls in this species’ territory, while one from Washington belongs to the northern species.
Where the grass stays wet
Jumping mice are tied to moisture, and this one follows the rule. It lives in streamside meadows, marshy pasture, sedge swales, and the rank grass along coastal streams, places that stay green and soft when the surrounding hills dry out. It eats grass seeds and green growth with insects mixed in, and it hibernates deeply, asleep below the frost line for much of the year on stored fat.
Reports run from spring through fall and near zero in winter, a curve that mixes real dormancy with observer effort. A jumping mouse asleep underground leaves no sign at all, so the quiet months are genuinely quiet in a way they aren’t for most mice.
Records under a young name
Because the split is recent, this species’ documented footprint is still settling. Dozens of records already carry the new name across Oregon and California, and older “Pacific jumping mouse” observations from the same country will migrate as databases catch up. Washington records under this name are essentially absent, matching the revised boundary.
No separate conservation status exists yet for the split. Coastal wet meadow has shrunk under drainage and development across its range, but the mouse persists in ditches, wet pastures, and stream corridors, and nothing suggests an acute decline. For now its story is the familiar one for a newly split species: an old, well-attested animal whose map is being redrawn, one re-identified record at a time.
