Where the Rattlesnakes and the Rodents Roam


I stopped stone still and scanned the ground around me. I was standing in the middle of a vast expanse of green grasses. Golden poppies, purple stork's-bills, and other flowers poked colorfully out of the plains. The spring sun beat down while a warm, dry breeze brushed against my skin. But the tingling I felt wasn't from the wind. It was from that loud buzzing sound. What was it?

Cautiously, I walked toward the noise. After 10 steps, I stopped. There, in an S-shaped striking position sat a rattlesnake. Its rattle whirred so fast, it blurred before my eyes. Its tongue flicked out. It looked menacing, but I wasn't scared. I knew that even though the snake was venomous, it had no wish to waste its precious poison on me. With its rattle, it was simply shouting ``LEAVE ME ALONE!''

I didn't blame it. I was spending my day hiking through the Carrizo Plains, an enormous grassland valley that lies between the Temblor and Caliente Mountains in central California. Although the plains were beautiful to look at, I knew that life for the rattlesnake and other animals out here was tough. Really tough.

Why? First of all, grasslands like the Carrizo Plains receive little rain - as little as 10 inches per year. Grasslands are often surrounded by mountains that block rain clouds. Some rain falls in winter, and thunderstorms bring a little more in summer, but months can go by without a drop. To survive, animals have to be able to conserve their water or get it from the things they eat.

Heat and cold are also problems for grassland animals. In winter, low temperatures ``freeze'' grasslands. In summer, the sun scorches the plains, and lightning sparks fires that blaze across the sun-baked landscape. Large mammals such as buffalo and antelope are big enough to ``tough out'' the harsh weather and fast enough to outrun the fires. Smaller animals, however, are forced to find shelter - a difficult task in a land without trees.

A third reason grassland animals have to be tough is that their home is full of predators - animals that eat other animals. My rattlesnake is a predator. It eats mice, squirrels, birds, and lizards. But other predators fill the plains. Foxes and coyotes trot down dry stream beds or slip through the grass. Hawks, kestrels, and falcons swoop down from the skies. To survive, grassland animals have to be able to avoid these enemies or defend themselves against them.

LOOKING at the rattlesnake, I could see it had the toughness needed to survive on the plains. Rattlesnakes are hunters, but they get more than food from the animals they eat. They get water, too, and they don't waste it. In hot weather, they ``keep cool'' by staying underground or in shade. When a snake does come out into the open, its hard scales keep moisture from escaping through its skin.

Since the rattlesnake is a predator, you might not think it has to worry about getting eaten. Not true.

Hawks, coyotes, roadrunners, and foxes all find rattlesnakes a tasty dish, and that's where the snake's rattle and fangs come in handy. The buzzing rattle warns other animals - both predators and hoofed animals that might trample the snake - to stay away. The fangs help the snake subdue its prey and make other predators think twice before trying to pick up a rattlesnake snack. All in all, I decided, it would be hard to design a better grassland animal than a rattlesnake.

But, it was clear that the snake didn't enjoy my company. Its rattle whirred, and it let out a loud hiss whenever I twitched a muscle. I didn't want to disturb the snake further, so I said goodbye and kept walking. A hundred yards later, I came across a far different plains animal - a ground squirrel scurrying about in search of leaves and other food.

The ground squirrel was a rodent - a creature unlike the rattlesnake. Yet, the ground squirrel also survived on the dry, harsh plains. How?

Like rattlesnakes, ground squirrels obtain water from the food they eat. Plants, roots, seeds, and insects are the ``drinking fountains'' these rodents need to survive. Unlike most other grassland animals, however, ground squirrels forage for food during the day when ground temperatures can soar to 150 F degrees. Scientists have discovered that ground squirrels have remarkable ways to survive this heat.

One thing ground squirrels do is let their body temperatures rise and fall with the surrounding temperatures. To live, most mammals must keep their body temperatures constant - about 98 degrees. Ground squirrels, though, function perfectly well with body temperatures as high as 105 degrees. By adjusting its body to the surrounding temperatures, a ground squirrel avoids the need to ``dump'' heat by panting or sweating.

What if temperatures get too high? Easy. The squirrel simply runs to a burrow or other shady spot and ``chills out'' by pressing its belly against the cooler ground. Then it can go back to eating or playing in the sunlight.

BUT solving the heat problem doesn't help the ground squirrel avoid hawks, coyotes, and other predators. The squirrel has no fangs to defend itself the way a rattlesnake does, so it usually runs to its burrow when danger approaches. Unfortunately, this ``run-and-hide'' defense doesn't work against one predator. You guessed it - the rattlesnake.

Rattlesnakes can follow ground squirrels right into their burrows. A ground squirrel doesn't take this fact lying down. Ground squirrels often ``duke it out'' with rattlesnakes.

If a snake approaches one of the squirrel's burrows, the squirrel chatters at the snake and throws dirt at it. Sometimes a squirrel even bites a snake. This might seem very dangerous, but researchers have discovered a remarkable thing: Many adult ground squirrels are resistant to rattlesnake venom.

Watching the ground squirrel, I marvelled at how different it is from the rattlesnake. Yet the ground squirrel, rattlesnake, and many other animals survived in this harsh grassland environment. One animal group that I haven't mentioned has survived especially well. People.

In years past, native Americans thrived on grasslands of Western North America. They hunted antelope, buffalo, and other grazing animals. They gathered roots and herbs for food and medicine.

More recently, people all over the world have turned grasslands into farms and grazing areas. The rich, deep soils of grasslands are ideal for raising cattle, sheep, and goats, and for growing crops. Over 90 percent of the world's exported grain is raised on former grassland areas. This is good for humans, but not for other grassland animals.

Grasslands once covered almost half of Earth's land surface, but today, few grasslands remain undisturbed by human activities. The Carrizo Plains is one of the last natural grasslands in California. It not only provides homes for rattlesnakes and ground squirrels, but also for owls, rabbits, hawks, antelope, tule elk, kangaroo rats, and endangered species such as the San Joaquin kit fox and the blunt-nosed leopard lizard.

To make sure that the Carrizo Plains continues to be a home for these animals, nature conservation groups have worked with local ranchers and government agencies to protect grasslands and their animals - including people. Conservation groups also are restoring grasslands in Oklahoma, Illinois, and other states.

We will never again see the almost endless prairies where giant herds of wild buffalo roamed, but at least there will be homes for rattlesnakes, ground squirrels, and other grassland creatures.

That was enough to make me smile as I said goodbye to my grassland friends and returned to my own ``burrow'' in the California suburbs. `Kidspace' is a place on The Home Forum pages where kids can find stories that will spark imaginations, entertain with a tall tale, explain how things work, or describe a real-life event. These articles appear twice a month, usually on Tuesdays.

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