Danger in the Meadow
The
Idaho ground squirrel stands on her hind legs and lets out
a shrill warning call. Her family scampers to the safety
of its burrow. The circling hawk will not dine on ground
squirrel today.
This family of ground squirrels escaped the hawk. But they face an even greater threat, which has reduced Idaho ground-squirrel populations to near extinction. The danger is fire. Not too many fires, but too few!
A hundred years ago wildfires, mostly caused by lightning strikes, occurred about every dozen years. The fires burned off pine seedlings, sagebrush, and grasses in western meadow areas, keeping them open.
Then the federal government began a policy of dousing all wildfires. Trees and brush grew tall in the open meadows, turning meadows into forests.
Biologists Paul Sherman, Tom Gavin, and Eric Yensen were alerted to the problem of shrink-ing meadows during their study of the Idaho ground squirrel. Some kinds of ground squirrels are so plentiful that they’re considered pests. But the Idaho ground squirrel is one of the rarest mammals in North America. Fewer than one thousand remain, only in isolated areas in western Idaho.
Long,
Deep Sleep
Idaho ground squirrels hibernate in underground burrows
from August until April. They spend the spring and early
summer eating plant leaves and the seeds of meadow grasses.
These nourishing seeds help the squirrels fatten up for
their long hibernation.
After ten years of studying the Idaho ground squirrels, Sherman, Gavin, and Yensen noticed an alarming trend. The number of squirrels had dropped from only one thousand to fewer than six hundred. Many of the animals disappeared during the winter hibernation, apparently from starvation or freezing.
Why did so few of the ground squirrels remain? The biologists discovered that the native bunch grasses in the squirrels’ meadow homes were nearly gone. Other, “non-native” grasses, introduced accidentally by settlers, had invaded the meadows and choked out the native species. The seeds of non-native grasses do not provide enough nourishment for the ground squirrel to survive the long, cold winter.
Sherman, Gavin, and Yensen noticed something else. Some small, isolated groups of ground squirrels disappeared completely. Dense forests had blocked the paths connecting the meadows where these ground squirrels lived. That meant that groups could no longer mix when their populations dropped because of disease, a hard winter, or predators. They eventually died off.
The
Creeping Forest
The biologists think the rapid drop in population was due
to the lack of fire.
Without regular fires, dense forests had grown where there
once had been open meadows of native grasses. Without fire,
native grasses, whose seeds can survive heat and flame,
lost their advantage over non-native grasses, whose seeds
cannot survive fire. Because the ground squirrels did not
have enough high-energy native grass seeds to eat during
the summer, they did not live through hibernation.
The Idaho ground squirrel wasn’t the only meadow resident affected by the lack of fires. When the open meadows disappeared, animals such as elk, bluebirds, goshawks, and robins could not find adequate food or safe homes. Native plants that thrive in a meadow environment also disappeared, followed by the insects that pollinate and feed on them, including bees, wasps, ants, and beetles.
Many forestry and wildlife experts think that regular fires are necessary to preserve native plants and animals. Forestry experts in the Payette National Forest are trying to help the meadow dwellers. In 1996 they burned two overgrown areas. A year later, after small native grasses and flowers began to grow, biologists moved fifty ground squirrels into these areas. The animals settled into their new meadow home, and some produced young the next spring.
Hot
Fires
Letting small natural fires burn has other advantages, too.
Without fires, fast-burning grasses and dense undergrowth
build up in meadows and forests. They act as fuel, making
small fires into big, hot ones.
The destructive wildfires that result are nearly impossible for firefighters to stop. During the last ten years, several huge fires have threatened cities and destroyed thousands of acres of forest in the West, including part of Yellowstone National Park.
A new fire policy that lets small fires burn doesn’t mean that people should stop being careful with fire. Everyone will still work to prevent dangerous fires around homes and businesses. Hikers and campers will still need to be careful when they use fire.
But for the Idaho ground squirrel and other meadow-dweling creatures, this new approach to fires means that their meadow homes may be saved.
