North Cascades

Mammals

SMALL MAMMALS

by Michele LaFontaine

Pika

"Eenk, eenk." Hikers passing talus slopes are familiar with the sound, if not the sight, of the pika, a small relative of the rabbit. The cry is both alarm (they are prey for several predators) and challenge (they are very territorial). When an alarm sounds, pikas disappear instantly into the rock crevices, eluding the hunter. These energetic lagomorphs spend the brief mountain summer gathering mixed greens, dashing about frenetically, then pausing to cast a wary eye around before scrambling off for another load. The plant material they collect is spread on rocks to dry. It's later stacked in rock crevices for storage. Since pikas don't hibernate like most small mammals, this "hay" is their sole source of food during long subalpine winter, lasting 9-10 months in some regions of the Cascades. When you hear the pika's call, stop moving -- stand still, and you may catch a glimpse of this busy harvester.

Bat

As dusk settles over the forest, they come -- navigating by sonar, silent flyers on leathery wings. Bats: creatures of awe and mystery. There are over 40 species of bats in North America but we know little about them because they are nocturnal. Bats come out when people go in. These small mammals eat more insects by body weight than any other predator, snatching their prey on the wing. Bats roost upside-down in large groups, sleeping all day and hibernating all winter. Some large species native to the Cascades migrate south in the coldest months. Mother bats nurse their young constantly in the first few weeks after birth, when they seldom leave their upside-down perch inside tree cavities or caves, even to feed. Old-growth forest, with snags, tree cavities and loose bark offer important roosting and nesting habitat for bats in the Cascades. Bats have extremely sensitive hearing. They use echolocation to locate prey and navigate, changing the speed and focus of their high frequency "blips" for precise aerial hunting.

Weasel

The long, thin body of a weasel is rare among warm-blooded animals -- it's not a heat efficient design. To keep warm, weasels need to eat approximately 40 percent of their body weight every day, more during cold winter months. But the shape is worth the cost -- a weasel can slip into any crevice, flow down any hole after their favorite rodent prey. They are aggressive hunters and seldom lose their quarry once the chase begins. The coat is soft, silky brown in summer and white in winter. Weasels are active year-round, and in winter their white coat makes them almost invisible against the snow. The tailtip stays black and is thought to serve as a decoy. Owls and other predators target the dark tail tip instead of the body and the weasel can usually pull away from a tailhold and escape.

Marmot

The ultimate sun-worshipper, hoary marmots spend hours sprawled rug-like on rock slabs in the high country, lazily surveying their domain. When hikers appear, marmots are apt to roll a wary eye and contemplate moving rather than making a mad dash for safety. Their high shriek-like call has earned them the nickname whistle-ping although the noise is not really a whistle at all -- it comes from the vocal cords. Marmots, the largest member of the squirrel family, excavate intricate burrows and passageways underground. They line their nests with clean dry grass, changed frequently. During the brief alpine summer, marmots put on enough fat to make up half their body weight, then the colony snuggles up together to conserve heat and beds down for about seven months. During rainy interludes they rarely venture out -- the marmot's thick, plush coat loses its insulating ability when wet.

Snowshoe Hare

When all the land is wrapped in snow and most forest creatures are deep in winter hibernation, the snowshoe hare moves silently through the forest. Its large hindfeet act like "snowshoes" allowing the hare to move quickly over me snow. And they need to move quickly -- foxes, great horned owls, golden eagles, weasels, bobcats, and lynxes all prey on this creature. While the hare's defenses of speed, camouflage - (the brown coat turns white in winter), and alertness are excellent, predatory pressure on them skyrockets during the winter when other small mammals are hibernating. The species survives the winter assault by prolific summer breeding. Females give birth several times a year, producing two to four young, born fully furred and with their eyes open. Hares appear to revel in the warm summer weather, indulging in footdrumming, rough and tumble play, and an ecstatic courtship dance when males and females take turns somersaulting over one another.

Flying Squirrel

The flying squirrel is seldom seen because of its crepuscular lifestyle (active in the hours before dawn and after dusk), but it is quite common. Distinguished by huge eyes and velvet-soft fur, this fragile squirrel doesn't really fly, but glides gracefully through the forest, stretching broad flaps of skin between its front and rear legs. In old-growth forests flying squirrels seek out old woodpecker cavities for nesting. Here the babies are safe until their eyes open at one month of age. Unlike most members of the rodent family, these squirrels like meat, but their main food in summer and fall is truffles. Truffles are underground fungi that provide vital nutrients to coniferous trees through a symbiotic relationship. Flying squirrels have an important role in the ecosystem -- spreading truffle spores throughout the forests. On quiet evenings, you may hear a soft chirp and the thump of a landing as they go about their nightly business of finding food.

Beaver

Ten thousand years ago, beavers the size of black bears roamed the continent -- and today beavers are still the largest rodent in North America. Beaver sightings are rare, but evidence of their handiwork is common throughout the Cascades: beaver dams, ponds, mounds, and beaver-gnawed trees. Beavers need only hear the sound of running water and the urge to build a dam takes control. Poles, saplings, and mud are dragged and piled into place to form a very efficient structure. Smaller mounds, or lodges, are constructed in the pond as living quarters. Hollow inside, with the entrance underwater, these lodges r provide a safe haven from predators. In areas where lodges aren't feasible, beavers construct burrows in river banks. After their pond freezes in winter, the beavers let some water out through the dam, lowering the water level of the pond and providing a "breathing space" between the water's surface and the bottom of the ice. Then they go happily about their business: feeding on poles stashed underwater in the summer, grooming, playing, and sleeping. Hunted and trapped almost to extinction for their pelts, beavers have made a comeback. Persistent and adaptable, they can even be found trying to construct dams near central Seattle and Portland.

LARGE MAMMALS

• Cougar
• Black and Grizzly Bear
• Mountain Goat
• Gray Wolf

ADDITIONAL READING

• Mammals of the National Parks, Van Gelder, John Hopkins University Press.
• Cascade-Olympic Natural History, Mathews, Raven Editions.
• Pacific Coast Mammals, Russo and Olhausen,
• Mammals of the Pacific States, Ingles, Stanford University Press.
• Mammals of the Pacific Northwest, Maser, Oregon State University Press.

Disclaimer: These books are listed as examples of titles available on this subject. Their listing does not indicate endorsement by the National Park Service.