Exploring
the habitats of
the North Cascades

Travel from the upper reaches of the North Cascades to their lowlands and you will pass through a multitude of habitats- unique communities of plants and animals. The story of the North Cascades life zones begins high in the mountains where winter snows accumulate to feed glaciers. The glaciers carve the mountains, grind the rocks into mineral-rich "glacial flour" and carry it down slope with streams of meltwater.

Below this region of perpetual snow and ice, you scramble among hardy flowers and clumps of stunted trees growing on rocky outcrops during the short summer. Following the stream lower down the mountainside, you enter the forests. Here an abundance of life thrives all around you-from under fallen logs to the highest branches. Streams join rivers. As they flow from the mountains to a broad river valleys, you meander through riparian habitats. The rivers deposit minerals and nutrients from the mountains to form rich wetlands teeming with aquatic life before flowing out to the sea.

Creatures of the Ice

Glaciers can be described as a life-spring in the North Cascades. Communities down slope and down stream of glaciers depend on the summer run-off. However, glaciers themselves appear to be sterile environments. In fact, glaciers support a variety of life which is still little known.

Some of the easiest organisms to spot are the various forms or glacial and snow-algae. You may see them as pink, yellow, green or purple areas on snow or ice. These organisms can live out their entire life-cycles on snow or ice, using wind blown or deposited minerals and decomposition materials for necessary nutrients.

The algae provides a food source for ice worms (Mesenchytraeus solifugus.) Ice worms are very similar to terrestrial worms, but they not only can live on glacial ice, they depend upon it. They are abundant in North Cascade glaciers (surveys suggest upwards of 2,000 worms/square meter) and spend the daylight hours burrowed into the ice. Once the ice is shaded, they come up to feed on algae and bacteria on snow and in slush pools. An evening visit to a glacier may see ice worms which appear as short dark threads scattered on the snow.

Ice worms are not found off of glaciers, not even in perinneal snowfields, so each population remains isolated. A major question then is how they dispersed originally. Mysteries surrounding cyro-ecology prompt a second-look at this indicative feature of the North Cascades.

Alpine Meadows

High-alpine habitats are defined by an environment with harsh winters, a short growing season and little soil or moisture. Fragile communities can be found on high slopes populated by plants and animals with unique adaptations.

The mountain goat is one of the famous denizens of high alpine meadows and crags. He travels where few others are able with a legendary sense of cool an unique hooves having strong outer edges and a rubbery sole for superior grip. Because of the isolated spots that mountain goats can access, they have few natural predators. However, they still lead a precarious existence. Mountain goats can eat nearly anything from lichens to herbs to tree branches, but forage can be scarce, especially in winter.

The North Cascades is one of the few places where native mountain goats can be seen. Please enjoy them from a distance. This will help sustain their population. People or dogs approaching the goats usually causes them to move to other areas which may have less desirable forage, which may decrease their chances of survival.

One plant that the goats eat is spreading phlox (Phlox diffusa), known for its beautiful pink flowers and compact, cushion-like form. It is frequently found on exposed slopes otherwise inhabited only by lichens. The plant forms a mat about 2-4 inches thick, but sends down a taproot 8-15 feet long to reach moisture. The compactness of the plant and its convex leaves ease the winds effects and collect windblown soils and snow.

Another plant well-suited to survival in this region is mountain heather (Cassiope and Phyllodoce spp). A common sight to the alpine hiker, heathers grow slowly on stony soils; the plants can be twenty years old or more. Heathers frequently precede forests. The plants gradually create favorable, protected conditions for trees to grow.

Travelers in Flight

Twice each year, three-quarters of North America's bird species undertake incredible long-distance journeys between wintering and breeding grounds. There are two major migrations that occur in the North Cascades every year. November through March, during the chum run up the Skagit, bald eagles come from as far away as Alaska to feed. The Forest Service, the National Park Service and the Nature Conservancy have long conducted surveys of their populations. While there is insufficient baseline data, and winter population varies, the past decade has shown an increase in the number of birds visiting the area. During the winter of 2004-2005, there were over 450 eagles seen on the Skagit during the peak season.

The bald eagles return north in February and March. In April, neotropical birds come from the south. The Rufous hummingbird spends its winters in Mexico but is a common summer sight here. Swainson's thrush, which is easier heard than seen in the forests, journeys to the mountains from as far south as northern Argentina and Paraguay. Unfortunately, many of these birds have been declining as habitat has decreased. Migratory birds pose special conservation problems. To better understand the birds and to work towards their protection, the National Park and Forest are participating in the Park Flight Program and others, working with scientists from Latin American countries to foster education and research.

Highrise Forests

Forests are much more than just trees. Typical western conifer forest, such as those found in the North Cascades, have many layers. The canopy, sometimes up to 300 feet above the forest floor, is dominated by one or two conifer species. The dominate species depends on both altitude and moisture. In the canopy, dozens of bird species make their nests. Other conspicuous residents are squirrels. They can be found nesting in cavities, collecting cones and chasing each other across branches. Less seen are marten and other small carnivores which hunts squirrels.

Beneath the canopy is a layer of shade-tolerant conifers and hardwood trees and shrubs. Maples, dogwood, yew and salmonberry are just a few examples of the plants that occupy this area. Many of these plants are important forage for animals such as elk, deer and bear.

At the bottom layer are various types of sedges, grasses, ferns and finally lichens and mosses. A great deal of activity goes on in this zone. A host of invertebrates including ants, termites, beetles, millipedes, springtails, pillbugs and earthworms live in this lowest layer or in the soil. Amphibians, reptiles, rodents, chipmunks, thrushes, sparrows and numerous others exploit this bounty of small prey as well as some of the understory vegetation. These animals in turn support larger predators such as coyotes and weasels.

Streams and Marshes

Throughout the mountains, water is constantly on the move in streams and rivers. Here, plants and animals must cope with an ever-changing stream bed and annual flooding. As the land levels out, watercourses slow. Silt and decomposing materials settle to form rich soil. The entire watershed is important to the health of the ecosystems that it connects, as well as the liveliehood of the diverse organisms that inhabit the region.

Salmon are an icon of the Pacific Northwest. The North Cascades supports populations of 7 anadromous salmonoid species: Chinook (king), coho, chum, pink, sockeye, steelhead and cutthroat trout. Anadromous fish, fish that breed in freshwater streams and spend their adult live in the ocean, are important both economically and environmentally. Salmon are rich in the nutrients that flow through the mountain systems to the sea. When they return to spawn, they die and return nutrients to the streams and, by predation, to the surrounding land. Salmon need cool, clear streams with pools, riffles and clean gravel.

In lowlands and at the edges of lakes, a completely different habitat exists. Wetlands and marshes are fed by very slow water. Abundant moisture, soil and decomposing matter makes these areas particularly rich. Sedges, grasses, cattails, willows and other plants form dense mats and ample breeding grounds for swarms of insects that in turn feed amphibians and populations of resident and migratory waterfowl. Wetlands are valued for their role in helping to maintain watersheds and urban water supplies.