A Heritage In Peril


On our western ranges, game and livestock protection and rodent control are hopelessly confused. The basic problem is overgrazing. The Texas longhorns were little more than replacements for the bison, and the longest cattle drives were, in their effect on the land, not unlike the buffalo migrations: a longhorn herd, always on the move, allowed the range to recover before the next drive appeared.

Then came the barbed wire and the windmills that made homesteading and the raising of pedigreed beef cattle the new industries of the plains. The stock farmer sank wells, making water available on dry pasturage, and brought in the shorthorns and Herefords that would, unlike the longhorns, live docilely behind fences. Inevitably he ran too many cows on his fenced-in pastures. Each cow needed at least thirty acres of prime grassland. With several cows on that amount of pasture, and perhaps sheep and horses, too, the farmer could manage only by supplementing the natural range grasses with field crops of sorghum and maize. But in a drought, the crops failed, weeds grew up on the worn-out land, and jack rabbits and rodents proliferated. On the circumstantial evidence alone, it seemed to many a ruined stockman that these animals—not the drought or the overgrazing—were responsible for the sorry plight in which he found himself.

But they had not been in really serious competition with his cattle for the range grasses. If he had looked carefully the previous year, when the range was still in fairly good condition, he would have seen that jack rabbits were feeding near a water trough, where the cows had already worn away the grass and a patch of weeds stood. Rabbits and many rodents actually prefer weeds. Nor, once the bison had been all but exterminated, was any of the big game animals ever in competition with cattle for food. The pronghorn antelope may be observed eating considerable quantities of weeds along fence rows and in gullies and breaks. Mule deer concentrate on shrubbery among the rimrocks. White-tailed deer browse high in the mountains, wapiti along the borders of coniferous forests.

On the other hand, the damage done by the stockman’s animals does affect the wild game. Continued overgrazing has prevented the return of the natural grasses of the range, like buffalo grass and bluestem. On the Big Bend in Texas, for example, where once there were great grassflats, only brush now grows, and much of this arid area has reverted to desert scrub, mainly creosote bush or greasewoocl, which none of the game animals can eat; the spread of this poor habitat lessens their chances for survival.

Two plains animals, however, were in part responsible for the stock farmer’s losses: the prairie dog, which does eat a good deal of grass (preferring the fertile river bottoms most valuable to cattlemen), and the coyote, which not only feeds upon the man-made irruptions of rabbits and other rodents but also attacks sheep, cattle, and starving game.

To eradicate these troublemakers, and particularly to kill the hardier coyote, more and more deadly poisons have been devised. At first strychnine was used, but its taste made coyotes shy away from the poisoned bait. Thallium compounds, developed after World War I, were thought to be the answer. They were tasteless and acted slowly, assuring that a lethal dose would be absorbed. The trouble was that thallium also killed other wild and domestic animals that ate the bait.

By the late 1940’s another nerve poison, sodium fluoroacetate (“1080”), had been developed. Theoretically, it could be used selectively, to kill only the coyotes and rodents for which it was intended. But 1080 turned out to be many times more lethal than thallium; a pound of 1080 is enough to kill a million pounds of animal life. Worse, it is highly stable in rodent bodies, causing secondary poisoning of scavengers and predators. Not only the coyote but the golden eagle, the kit fox, the black-footed ferret, or the condor that dines on a ground squirrel killed by a particle of 1080 may also die. Thus, rare and desirable animals, as well as the so-callecl pests, have become the victims of an ill-considered policy.

Today the traditional rationale of predator and rodent control is being challenged. Scientists are beginning to wonder whether it is sensible to kill both the rodents and rabbits and their predators. Similarly, questions are being raised about whether the money spent on killing certain predators is justified by the returns. Considerable government funds are being spent, for example, to kill coyotes throughout California’s national forest lands, though only a small part of these areas is being used for sheep grazing.