About Zapus trinotatus Rhoads, 1895
Pacific jumping mice (Zapus trinotatus Rhoads, 1895) can be distinguished from other members of their genus by their larger body size. They have a clear, distinct color difference between their back and underside. Compared specifically to the Western jumping mouse, another key distinguishing feature of Pacific jumping mice is that their ears are fringed with light brown fur, or fur that matches the color of their back. These rodents prefer to live in moist habitats, and are most often found in riparian zones or meadows located near small streams. Their main diet is grass seeds, so they favor areas with thick vegetation, which provides both protection from predators and access to their primary food source. In addition to grass, Pacific jumping mice also eat fungi and insects. Throughout most of autumn, these mice gain fat stores to prepare for winter hibernation, which they spend in small underground burrows. After hibernation ends, a period that can last up to 8 months, they mate and produce a litter of four or more young. Their known predators include snakes, coyotes, owls, and foxes. Their preferred moist distribution areas include marshes with alder, salmonberry, and skunk-cabbage, as well as riparian alder ecosystems common in coastal redwood woodlands. In more northern parts of their range, they live in dense woodlands, wet grassy areas, and alpine meadows of the Cascade Mountains in Washington and the Olympic Peninsula. They can also be found in marshy thickets, woodland edges with weedy undergrowth and ferns, and open meadows. The full range of habitats used by Pacific jumping mice includes streams, brushlands, lakes, woodlands, forests, fields, swamps, meadows, shrub areas, bogs, marshes, and the banks of rivers and ponds. Their overall geographic range covers the entire Pacific Northwest of the United States, California, and western Canada. Pacific jumping mice reach sexual maturity the year after they are born. Males become sexually active in May or June, which is when females are also fertile. Their gestation period lasts approximately 18 to 23 days, and females give birth in July or August. Each litter contains between 4 and 8 young, which are weaned after 4 weeks. Newborn Pacific jumping mice are pink and hairless, weigh 0.7 to 0.9 grams at birth, and are born with their eyes closed. They depend entirely on their mother to survive their first few weeks of life, and become fully independent after about one month.
