The Beaver Makes a Comeback

FOCUS ON NATURE RETURN OF THE BEAVER RASCALLY RODENT EXTRAORDINAIRE By Joseph Stocker

Consider the many lives of Castor canadensis, that largest of the rodents of Arizona and, indeed, of the North American continent. I speak in admiration and yet just a mite reproachfully of the beaver.

He's an engineer. He's a builder. He's a conservationist. He's a skilled logger.

And he's a rascal and a nuisance. Coming back strong from near extermination by trappers in the 19th century, he plugs drainage culverts in the East with his assiduous dam-building and inundates croplands in the Midwest. A beaver dam in Canada caused a flood that closed the Trans-Canada Highway. In Arizona beavers plug up irrigation pipes. They burrow into canals, and the canal banks collapse. Along Oak Creek, they gnaw down apple trees. Along the Colorado River, they chew out pieces from the plastic foam floats of boat docks. The docks are built around the foam cores to rise and fall as the water level fluctuates with release from the dams. The beavers don't eat the foam. They use it for dam-building material.

"They're very resilient creatures," says John Hervert, wildlife program manager in Yuma for the Arizona Game and Fish Department.

On Burro Creek, southeast of Kingman, the U.S. Bureau of Land Management planted trees as part of a riparian improvement. Some of the trees were tagged. Ted Cordery, BLM threatened and endangered species specialist, says branches with the tags still on them were found later in a beaver dam. BLM is fencing a lot of its new trees now.

All right, then. The bright side of things a la beaver: his dams spread the water around to create meadows and new forests. Silt is deposited instead of washing away. The land is enriched. New abodes for wildlife come into being. Species of fish thought extinct suddenly reappear. Spring runoffs that just washed down the valley and did no particular good are substantially slowed. Erosion is checked. Says Hope Ryden, who spent four years watching a family of beavers at work and then wrote a book about it titled Lily Pond, "The beaver is truly our best agent for renewal."

Why do beavers build dams? They do it to raise the level of the water to create a pond in which they then build another structure called a "lodge." Here, underwater, they store their winter food supplies before the freeze comes. And in the lodge, truly a castle with a moat around it, they wait out the winter mother, monogamous father, and offspring called "kits," all reasonably safe from predators.

Dam and lodge are made of anything and everything the beaver can latch onto and haul into place: sticks, stones, mud, beverage cans, pieces of old railroad ties, and, yes, chunks of plastic foam. (Beavers in warmer country such as (LEFT) A large semiaquatic rodent with webbed hind feet, the beaver also has a broad flat tail it uses to slap the water as a warning signal to other beavers in times of danger. An adult may be up to four feet long, 15 inches high, and weigh 60 pounds.

(RIGHT) Beavers build dams to form ponds for their lodges, where they live monogamously in colonies with their families.

Arizona tend sometimes to make their homes by burrowing into stream banks.) The beaver here is the same species found throughout North America, but it's commonly known as the Sonoran beaver. It is lighter in color than its cousins of the East and North, possibly because of the bright sunshine, and with not quite as rich a pelt. Yet it was this lowly Sonoran beaver - not the glitzy lure of gold or silver that brought the first Anglo Americans to Arizona early in the last century.

In the East and in Europe, hats made of beaver fur were very in, and the fur trade drove exploration of the North American continent. And so there came to Arizona the mountain men: Bill Williams, James Ohio Pattie, Paulino Weaver, and scores of others. They explored and they named places and they trapped beavers.

Arizona's Sonoran beavers were plentiful. What we now know as the San Pedro River in southeastern Arizona, for instance, was dubbed "Beaver River" by that redoubtable Kentuckian James Ohio Pattie.

But sartorial tastes changed. Beaver hats went out, silk hats came in; and the beaver boom fizzled. But by then the beavers were nearly extinct. Late in the century, only five beavers were known to be alive in the entire state of New York.

Protection measures were invoked and gradually took hold. Nationwide, right now, the beaver population is in pretty good shape. And there are undertakings in Arizona and elsewhere to put beavers back where they used to be, simply because they improve the ecosystem. BLM is talking of restoring beavers to the San Pedro as part of a riparian conservation project. And west of Wickenburg, two ranchers are working with Arizona Game and Fish to restore beavers to Date Creek. As this was written, one beaver was on the premises and presumably doing his beaver thing. Wildlife experts have an interesting term for beavers: "keystone species." That's because their influence is so pervasive, and they play such a critical role in regulating an entire ecosystem. Rather obviously, then, whether eco-benefactor or eco-nuisance, the crit-ters inspire a lot of affection from folks. They affect our world. They belong.