Just what is habitat, anyway? It's food, water, shelter and space. These are the four basics for all animals -- whether it's elk, elephants or elf owls -- and people, too.
The need for food is obvious. Picture a 900-pound bull elk grazing in a meadow of bunchgrass. The bull's hoof thumps down beside the nest of a field mouse. When the mouse panics and flushes, it's pounced on by a shrew that weighs no more than a quarter. Both the elk and the shrew rely on the same habitat -- and are driven by the same hunger.
Well actually, the shrew may be a little hungrier. Elk need 10 to 15 pounds of vegetation per day, but shrews have to eat their own weight in insects, earthworms or mice every day or starve. Elk can go a bit longer between meals. But like all animals, they cannot survive for very long without food.
Water is just as critical. Your body, an elk's body, a weasel's body... is all wet. If all the water in your body were removed, you would weigh about as much as a dictionary.
Naturally, elk and other animals are drawn to water holes -- springs, seeps, lakes, creeks -- but there's more than one way to come by water. A sharp-tailed grouse that shares grasslands and wild rose thickets with elk can get all the water it needs by sipping dew and eating juicy plants. Elk use these same techniques, and they also eat snow to quench their thirst.
After getting enough food and water, elk look for shelter. Shelter works two ways. It protects animals from cold, rain and snow. And it gives them a place to hide from predators.
On a bitter, cold, snowy day, a band of elk may "hole up" in a big stand of spruce trees. These trees form a great green blanket, holding warmer air near the ground. The spruce also take the bite out of the wind. And their tightly woven branches catch much of the snow before it hits the ground. This same patch of timber also offers shelter (and food) to a variety of songbirds, chickadees, nuthatches, grosbeaks -- and maybe even a red fox.
When people and mountain lions are hunting elk in October, the elk head for the north slopes of mountains and burrow into thick stands of dark timber. Lurking among the deadfalls where pine martens live, the wary elk position themselves so they can smell, hear and see any intruder long before they themselves are seen.
Every animal needs room to roam. For a mature male mountain lion, that means a lot of room. A big tom can have a home range of more than 100 square miles. That's as big as an entire county in some states. Elk like to ramble, too. They have been documented trekking more than 50 miles in a single day.
But a ground squirrel may spend a whole year on a chunk of range no bigger than a football field. And a beetle may live out its life on a slice of elk country the size of a wading pool. The beetle needs its space -- the area in which it finds the critical triangle of food, water and shelter -- just as much as elk do.
Elk country is home to all sorts of wildlife -- from tiger salamanders to zebra swallowtails to cutthroat trout. These creatures don't have antlers or horns or big brown eyes. But they're all vital strands in the web of life.
When an old bull dies in February, coyotes, ravens vultures and magpies quickly clean up the meat. Next spring, gophers gnaw on the bones for calcium and other minerals. When one of the gophers dies, beetles eat its decomposing carcass. And what's left over decays into the earth and is reborn as more nutritious grass.
All of the creatures in elk country have evolved over thousands--perhaps millions--of years to live in a specific habitat. When the rug is yanked out from under them -- when their food, water, shelter or space is suddenly altered or destroyed -- many of them cannot adapt quickly enough to survive.
Given a chance, the land can allow these animals to live naturally. All they need is habitat.
Populations and Habitats
From an ecological point of view, individuals of an animal species are less important than populations. Only populations can survive and adapt over the long term.
"Habitat" is the foundation on which wildlife populations are built. Habitat is a particular combination of (1) food, (2) water, (3) cover and (4) space needed by individuals and populations to live and thrive. The quantity and quality of these habitat components generally dictate the type and number of animals that can live and persist in a particular area.
Habitats are always changing -- seasonally, annually and over longer periods. Such changes can be the result of seasons (spring, fall, etc.), natural catastrophe (flood, drought, tornado, wildfire, etc.), plant succession (a field growing up to forest, for example) or human action (agriculture, dams, logging, pollution, etc). Thus, while the number of animals that any habitat can support always is limited, the actual population can sometimes vary drastically over time.