American Bison: A Natural History / Edition 1 available in Paperback
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- University of California Press
American Bison combines the latest scientific information and one man's personal experience in an homage to one of the most magnificent animals to have roamed America's vast, vanished grasslands. Dale F. Lott, a distinguished behavioral ecologist who was born on the National Bison Range and has studied the buffalo for many years, relates what is known about this iconic animal's life in the wild and its troubled history with humans. Written with unusual grace and verve, American Bison takes us on a journey into the bison's past and shares a compelling vision for its future, offering along the way a valuable introduction to North American prairie ecology. We become Lott's companions in the field as he acquaints us with the social life and physiology of the bison, sharing stories about its impressive physical prowess and fascinating relationships. Describing the entire grassland community in which the bison live, he writes about the wolves, pronghorn, prairie dogs, grizzly bears, and other animals and plants, detailing the interdependent relationships among these inhabitants of a lost landscape. Lott also traces the long and dramatic relationship between the bison and Native Americans, and gives a surprising look at the history of the hide hunts that delivered the coup de grâce to the already dwindling bison population in a few short years. This book gives us a peek at the rich and unique ways of life that evolved in the heart of America. Lott also dismantles many of the myths we have created about these ways of life, and about the bison in particular, to reveal the animal itself: ruminating, reproducing, and rutting in its full glory. His portrait of the bison ultimately becomes a plea to conserve its wildness and an eloquent meditation on the importance of the wild in our lives.
About the Author
Dale F. Lott (1934-2004) was Professor Emeritus of Wildlife, Fish, and Conservation Biology at the University of California, Davis. He is the author of Intraspecific Variation in the Social Systems of Wild Vertebrates (1991).
Read an Excerpt
American BisonA Natural History
By Dale F. Lott
University of CaliforniaCopyright © 2002 Regents of the University of California
All right reserved.
Chapter OneBull to Bull and Cow to Bull
The sky really is bigger in Montana-a colossal inverted bowl of vivid blue. In late July and early August, plumes of dust, rising with earth-warmed air from the brown grass and rolling rangeland, ascend into that bowl. The dust makers, a herd of bison on the National Bison Range, are going about their business-breeding; and I am going about mine-observing, recording, and trying to understand their behavior.
Most of the dust comes from wallows, shallow pits where the bison have torn away the sod with their horns and where the subsoil, dried by the sun and stirred by hooves and horns, turns to a flourlike dust. Some of the plumes start when threatening bulls paw and roll in these wallows; but most occur when fighting bulls plow the soil with their hooves, or when they slam their heads together and the shock explodes dust from their bodies.
Now an old bull bellows. His back arches, his belly lifts, his neck extends, and a sound that seems equal parts lion's roar and thunderclap booms across the grass. An eighteen-inch scar runs up his ribs. His horn tips, shattered in other battles, are blunted and worn. Fifty yards away his opponent, a six-year-old bull in his prime, bellows back, glances at the cow he is tending, then urinates into the dust of a wallow and rolls in it, slamming his 2,000 pounds sideways into the dust. It spurts from beneath him, filling the air around him like the burst of smoke a stage magician vanishes into.
The prime bull emerges from this cloud, headed toward the old bull in a menacing walk. His forefeet stamp with each step, making the hair pantaloons on his legs dance and exploding little puffs of dust from his coat. As each front foot stamps, the bull snorts. His tail stands up like a living question mark. It's an impressive display, and from where I sit, in an ancient jeep, an intimidating one. But the old bull is not intimidated. He too has wallowed and now advances, matching stamp with stamp, snort with snort. As they grow closer their bellows intensify; they seem to signify pure fury.
Most such challenges seem to be elaborate tests of the opponent's determination and end without a fight. Most fights involve a cautious locking of horns or hooking uppercuts or shoving head to head, ended when one animal signals submission and the winner lets him go. But this is not a test of determination and it's a different kind of fight-one of those in which the bulls hurl themselves at each other, elongating their bulky bodies into animated battering rams as they launch themselves for the first blow. Their heads come together with a terrific shock. It ripples through their bodies in a visible wave. I once saw a bull somersaulted backward by such a charge: 2,000 pounds of bull flipped upside down like a lawn chair in a gust of wind.
Both these bulls hold position after the first shock and dig in for a serious fight. They slam their heads together again. Clumps of hair the size of a fist are caught between their short, heavy, curved horns, then sheared off and tossed into the air. The animals circle, each trying to reach the other's flank with a hooking horn. Both pivot around their forefeet with the speed of featherweight boxers, and each parries the other's seeking horns with his own while their powerful necks absorb some of the force of the impact. Their hair absorbs some too. By the time a bull is six years old, a mat of hair several inches thick extends from the top of his head down across his forehead, thinning gradually until it stops just above his muzzle. His eyes peer from shallow wells, his ears flick out from deep recesses, and the space between his horns is completely filled with this luxuriant growth. Beneath this natural shock absorber, a thick layer of tough hide covers a rock-solid skull.
Now the bulls lock horns and push hard, their hooves plowing soil as each tries to drive his opponent back. The old bull is pushed back and a little sideways, dust spurting from beneath his skidding feet. Suddenly a foot catches on a rock and he trips and falls onto his side.
It is rare for a helpless bull to be attacked by the winner, but this time it happens. The younger bull strikes down and forward with his horns, slamming them into the old bull's flank and hooking right and left. The curves of his horns make most of the contact and deliver bruising, possibly rib-breaking, but not fatal blows. Then the tip of one horn plunges through skin and muscles and into his opponent's abdomen. Only one horn penetrates, and it penetrates only once, but the wound will be mortal.
The younger bull ends his attack and returns to his cow. In a few minutes the old bull will rise to walk away. He will graze again, drink again, sleep again. But an infection will send matter oozing down his ribs in a few days, and in a few weeks it will kill him.
Yet as one life starts to ebb, another begins. The victorious bull has mated with the cow he was defending and a calf has begun to form. Its birth is the renewal that has made North America bison country for thousands of generations. Siring as many as he can of that calf's generation is the bottom line for each bull, and it's the imperative that justifies their risking their lives in the battles their bodies are built for.
But while physical prowess is an essential tool in managing a relationship between two males, it can't be the only tool, and in fact it's one of the least-often used. Much more frequently they use communication, which evolved as a means not to transfer information but to do what attacks do-manage another individual's behavior to one's own benefit. In some relationships honesty is the best policy, and communicating animals transfer real information. A mother hen calling "food here" to her chicks is managing their behavior to their benefit as well as hers by telling the truth. They get food, and she gets her genes represented in the next generation. On the other hand, young men in a hormone-induced haze who exclaim, "Of course I love you!" while fumbling with a woman's bra are often lying through their teeth. But both the hen and the men are using signals in fundamentally the same way-to modify another's behavior for their own benefit.
It starts with anticipation. A bull's defenses work only if he knows when and where to deploy them-he must anticipate attacks. So the bull must be a seeker-actively scanning or even probing his environment for clues about whether or not he is likely to be attacked. Call it actively anticipating.
A territorial animal can predict attack pretty successfully by knowing territorial boundaries. The territory owner usually challenges all competitors within a given space and keeps up the pressure with threats and attacks until they leave. But bull bison aren't territorial. They are roamers, drifting singly or in small, temporary groups. Because they cannot use their location in space to predict whether or not another animal will attack them, they read the animals around them, detecting and responding to behavior that consistently precedes an attack. Reading it accurately is a second tool for managing relationships.
It's clearly to the advantage of an animal about to be attacked to become canny in judging his enemy's behavior. Generally the task is made easier by the opponent, who, instead of disguising the coming attack, often amplifies preattack behaviors, draws attention to them, and in every way makes it easy to see what he is about to do. A bull doesn't just walk toward his opponent: he stamps with each step, setting his foreleg pantaloons dancing, and grunting with each stamp. If forewarned is forearmed, why not attack first and give indication later? The reason, of course, is that it may not be necessary to attack at all. Forewarned may be foredefeated-at least often enough to make the warning worthwhile. Call these forewarnings threats. A fight avoided is also risk and energy expenditure avoided. Fighting is an occasionally necessary grand spectacle, but the real biological drama lies in the complex, drawn-out, and frequently subtle ways in which most conflicts are settled by communication.
Bulls do most of their communicating during the breeding season-the only time during the year that mature bulls and cows are together for any length of time. The bulls have been alone or in small, temporary groups. Now they join the cows, which have been living in larger groups with the calves and young bulls. The bulls seek out cows about to breed and stay with them (they "tend" them), keeping other bulls away by threatening and fighting.
But threatening and fighting are also common between bulls that are not defending cows. Since receptive cows are the only scarce resource in the bull's economy, this seems surprising at first: one wonders what the nontending bulls are fighting about. But a rival dominated now will probably give way later without a contest, saving a tending bull time and energy when he has none to spare. Not that the bull works it all out in this fashion. He simply has a powerful urge to dominate other bulls, and following this impulse works to his advantage. The drive to dominate is so powerful that it occasionally interferes with his real business and its ultimate function-bulls will sometimes leave a receptive cow to threaten a distant bull.
Virtually all of us air-breathing vertebrates have found ways to turn our exhalations into communications, and most interactions between bulls start with a sound. On a still day a bull's bellow carries for miles. It's a sort of roaring rumble, and if you can't see the bull or don't recognize the sound you may guess it's a thunderstorm. If the competition presses, the bellowing becomes louder, and a quality that is hard to define but somehow easy to recognize-a quality of fury-begins to grow in it. Often one or both bulls will interrupt their bellowing to paw the ground or wallow.
Threatening bulls usually do something we don't understand at all: they urinate into a wallow, then roll in the dampened soil. Do they get enough urine on themselves to send a signal? If so, what could they be signaling? Could they be exposing the opposition to an index of their testosterone level as salient to a bull bison's keen nose as their bulk presented broadside is to his eyes? Or is there another chemical billboard being displayed? As a bull uses up his physical resources during the rut, he eventually begins to metabolize his muscle. The metabolites in his urine will report that chemistry to a sophisticated nose, and the same nose will know when the bull is still burning fat and his muscle is intact. This would be an honest signal of physical condition. The cost of signaling weakness when you are weak would be compensated for by the benefit of signaling strength when you are strong. An intriguing story, but so far 100 percent speculation. Maybe someday we'll know.
If the challenge does not end at the wallowing or bellowing stage, the bulls draw closer to each other and begin to posture. There seem to be two distinct postures. In the "head-on threat," which is simply the posture and movement that precedes a charge, the bull moves toward his opponent with his head held slightly to one side. The more slowly the challengers are moving, the farther to the side their heads are held. When they approach nearly straight on, either one bull submits by turning away or they bang heads. But when they approach slowly with their heads well to one side, they often stop close to, but not quite touching, each other and "nod-threat."
Nod-threatening bulls stand close enough to reach one another; their bodies may form a single straight line or an angle of up to ninety degrees, but in either case they turn their heads aside. From this position they can attack suddenly by hooking a horn into the opponent's head. The hook always starts when the head is close to the ground, the muzzle tucked back. But in the threat itself, the head-low, muzzle-back position is only a brief interruption of a head-high stance: the bulls' heads drop in a matched movement, then swing back up again, still to one side. A hooking attack may start at the bottom of any one of the down swings, but the opponent never seems to be caught off guard. After a series of such nods one animal may suddenly submit, ending the clash.
Nod-threatening takes place most often between bulls that are not tending cows, as does the "broadside threat." A bull in this posture keeps himself broadside to his opponent with his head held a little higher than normal. Usually his back is arched and he is bellowing. If he moves, he does so slowly, in short, stiff steps that keep him broadside to his opponent. Often two bulls will threaten by standing parallel to each other just a few feet apart. Only rarely does this threat lead to a fight. The encounter may be long as threats go, lasting up to a minute or more, but one of the animals almost always submits.
The broadside threat and the nod threat emphasize the degree to which the bulls forewarn their opponents. This forewarning is so elaborate that it has become a force in its own right. It goes beyond permitting the prediction of attack: by substituting for attack, it often overpowers the opponent.
That function may account for some puzzling aspects of these postures. Why, for example, do the bulls threaten by turning broadside? When turned this way, a bull seems very vulnerable to attack, particularly if the bull he is threatening is facing him. Since all his protection is concentrated at his head, the usual point of attack, a bison bull is easily wounded by a horn thrust from the side. (This danger, by the way, is more apparent than real. In watching thousands of such threats I have seen only one attack on a bull turned broadside.) Perhaps the function of the broadside threat is to display the full size and power of the bull, as well as to forewarn the opponent. If the threatening bull makes a big enough impression, he may save himself a fight.
The one recurrent note in all these descriptions of fighting and threatening is that they go on until one animal submits. Submission signals have two functions: they enable a bull to withdraw from an encounter without getting into a fight, and they enable a losing bull to end a fight without retreating a long way. There are two questions to ask about bison communicating submission: How do they signal it? Why do the winners accept it?
All bison submission signals are variations on a theme: the submitting bull turns away. Sometimes it's a 180-degree turn followed by a galloping retreat. At other times it's an abbreviated swing of the head and neck to one side. When it involves a 90-degree turn, the submitting animal ends up in the same general position as one who is threatening broadside. But it's easy to tell the difference.
Excerpted from American Bison by Dale F. Lott Copyright © 2002 by Regents of the University of California. Excerpted by permission.
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Table of Contents
List of IllustrationsForewordPrefacePart One. Relationships, Relationships1. Bull to Bull and Cow to Bull2. Cow to Cow3. Cow to CalfPart Two. The Machinery of a Bison’s Life4. Bison Athletics5. Digestion: Grass to Gas and Chips6. Temperature ControlPart Three. Whence They Came Forth, and How Much They Multiplied7. Ancestors and Relatives8. How Many? Bison Population in Primitive AmericaPart Four. The Bison’s Neighborhood9. The Central Grassland: Where Buffalo Roam When They’re at HomePart Five. The Bison’s Neighbors 10. Wolves and Bison: Myths and Realities11. Buffalo Birds12. Diseases and Parasites13. Pronghorn14. Prairie Dogs15. Badgers16. Coyotes17. Grizzlies18. FerretsPart Six. Human and Buffalo19. Close Encounters of the Buffalo Kind20. To Kill a Bison21. Bison Numbers before the Great Slaughter22. Where Have All the Bison Gone?23. Attitudes24. Conservation: Then and Now 25. A Great Plains ParkNotesBibliographyIndex