Over a decade ago on a snowy day in early October a bull moose I named Big Boy died in the Savage River country of Denali National Park. He was a warrior who fought and won against many other bulls during his life. I didn't see the battle that resulted in his death, but I'm sure he fought it as he did the others -- with skill, strength, and courage. As part of a moose research project, he taught me a lot during the six years I knew him, and upon his death I reflected on what it means to be a moose, how difficult a moose's life can be, and how exceptional animals like him survive until the end despite the odds.
During his prime, Big Boy wore a radio collar that allowed us to identify and locate him
daily as we studied the moose rut, or mating season, each year from August to October. We followed about twenty collared bulls and cows each year, learning about the areas they used, their traditions, their choices of mates, the behaviors they used, and how these things varied from year-to-year depending on changes in the environment and weather. Earlier, I became interested in fighting among bulls after another collared bull broke off an antler in a fight and died from his injuries. The vast majority of fights did not result in serious injury or death, so I wanted to learn much more about fighting to determine who won and who lost, and hopefully understand why. When I first saw Big Boy several years later, I knew from his size and bearing that he could help me in my quest.
Denali is one of the best places on earth for observational studies of moose. Prior to working there I was an "airplane biologist." Like most of my colleagues, I spent a lot of time in the back seat of a Super Cub radio tracking moose, mainly collecting data on their locations, associates, and mortality, but seldom seeing much of their behavior. At Denali a whole new world opened to me, the chance to be with moose on the ground at close range as they did everything a moose does from mating to giving birth. Here, most moose ignored me as they went about their lives, and in a few months I learned far more about what it means to be a moose than I had learned from the air during several years.
Those who know little about moose, or any wild species for that matter, may wrongly assume that individuals are pretty much alike, stamped out like clones as a result of similar adaptations to the same environment by long-dead ancestors. As a young wildlife biologist, I underestimated how much animals differed. It was not until I began to study individual moose closely in Denali that I realized moose were highly variable in nearly all regards. Some bulls were much larger than others. Some had massive antlers. Certain cows were successful at raising calves; others lost them year after year. During severe winters, some moose knew where to go and what to do to survive while others starved. These differences applied to nearly every visible aspect of their shape, form, and behavior, as well as to the invisible things like physiology and metabolism. In short, some moose were much better than others at surviving and passing on their genes. For bulls, the bottom line of success is the ability to win fights, avoid injuries, and mate with many cows.
I didn't know Big Boy as a "child" or a "teenager." Was his mother smart or just lucky to raise a calf when about 85 percent of all calves at Denali die, many from predation, during their first few months of life? Was he smart or just lucky to survive the critical months following separation from his mother after a year of her care? How quickly did he learn the rules of moose society during the rut as a yearling or two-year-old when he was at the bottom of the pecking order, pushed around by the larger bulls and spurned by the older cows? I could never know these things having first collared him as a seven-year-old coming into his prime.
At seven he was fully-grown and about as large as bull moose get, about 1,600 pounds. Most other bulls in the area were smaller and none that year carried larger antlers. Big interior Alaska bulls grow antlers spanning 65 inches with a few exceeding 70 inches. Big Boy's antlers not only had a wide spread but also had great mass, wide palms, and long points. Along with everything else, he was handsome. Some bulls have scarred faces, rough coats, potbellies, or other unattractive features. Big Boy was sleek and unscarred, with a long, full bell hanging from his chin, an Errol Flynn sort of moose with a personality to match.
But appearance and size alone are not enough to ensure success at fighting. Like human boxers, bull moose need a host of traits to be winners. Size is important, but speed, strength, agility, and endurance also count. Fighters must have ambition and motivation to train hard for years, sacrificing things that might harm their careers. And the best fighters have a rare combination of courage, confidence, and brains that carries them through the most difficult bouts when others quit. Only a few humans become heavyweight champions, and only a few bull moose have what it takes to be dominant over their rivals. As I would later learn, Big Boy had the right stuff.
Fights among bull moose are truly spectacles of nature. They begin as two bulls advance toward each other, at times from several hundred yards away, each walking stiffly, tilting his antlers from side to side. This gives each time to see the other, to determine his body and antler size, age, and condition, and to assess his chances at winning against this particular rival. As they reach each other, they turn sideways, paw the ground, tilt their heads, flare their eyes, and lower their ears, all threats and displays of intimidation. Often, one bull will soon turn and run, having decided against actual combat. If both persist, there comes a mighty clash of antlers that can be heard a mile away. For a few minutes, both bulls push with all their strength, each trying to gain the advantage by twisting his antlers into the opponent's body. Long fights may last several hours and involve twenty or more clashes before one bull is defeated and runs off, but the contest is usually decided after about 15 minutes. The battle scene of a long fight is littered with broken small trees and torn up brush, and bits of hair gouged out by trees or antlers. Wounds ranging from minor to major are common. Faces are scarred, eyes are damaged, flanks and hind legs are punctured, and rarely, bulls are killed outright if they lose their footing and are severely gored. More commonly, wounds infect and death comes slowly after several months.
Why do moose risk their lives in such violent battles? They do it for the chance to control and mate with a group of cows, to be successful breeders. In the north, moose form rutting groups consisting of several cows, one dominant bull, and a series of other bulls that may challenge the leader. Typically, these groups have fewer than eight cows, but at times there may be more than twenty. The groups form by mid-September and persist through the mating period, late September and early October. With few exceptions, the cows mate with the dominant bull, simply because he defends them from other males. For smaller or younger rivals, intimidation is sufficient. Dominant bulls are kept very busy threatening and chasing off these smaller pests. But for serious rivals, only fighting will determine who will control the group. During the peak of the rut, the ruler of a large group may fight three or more times a day. Under the constant pressure of mating, fighting, and intimidating lesser bulls, dominants rarely keep control of a group for long.
For every round they spend in actual combat, human boxers spar dozens of rounds in the gym. Similarly, as young bull moose age, they spar long and often with young companions. Older bulls seldom waste much time sparring. During the rut, frustrated by failure to mate with cows, young bulls gather at the fringes of groups and spar. This continues well into November when mating activity is long over and cows disperse from the groups. Sparring is gentle pushing unaccompanied by threats or displays and without winners or losers. It is practice fighting during which bulls learn about their opponents and acquire the skills they need to fight. Unlike real fights, sparring matches seldom turn violent. Sparring is much more common than fighting and many photographs of "fighting" moose locked in mortal combat actually portray gentle sparring.
In places like Denali where hunting does not remove older bulls, young bulls spend the first five or six years of their lives in training. Some will have everything it takes to be dominant while others will not. Some of the bulls I collared over the years were reproductive losers. Chip and Buddy were smaller than average with antlers that barely spanned sixty inches. Other bulls were successful at times despite their small size because they had good fighting skills or exceptional courage and patience. But Chip and Buddy never seemed to acquire the necessary skills. They spent the rut wandering from group to group, at times losing fights, but often not even bothering to challenge the bosses. Occasionally, they found cows away from rutting groups and spent time with them. Often, another, larger bull would arrive just as a cow was ready to mate and drive off the hapless, hopeful suitor. But Chip and Buddy reaped one benefit from their life of few fights and rare matings. Both lived longer than average and died from causes other than fighting.
By six or seven years of age, bulls like Big Boy are large enough and have enough experience to hold groups of their own, if only for a brief time as older, more experienced rivals displace them. If they are skillful and lucky, they will survive and bide their time until the following year when perhaps a few of the older bulls will die thereby creating openings for newcomers. This was the path that Big Boy followed.
I first saw how different Big Boy was from most other bulls on a warm September day early in the rut when Big Boy was about eight. He had a group of about a dozen cows separated from another group of similar size a half-mile away. Something spooked Big Boy's cows and they began to run toward the other group with Big Boy bringing up the rear. By the time they reached the second group they were overheated. Instead of immediately approaching the rival bull, Big Boy laid down and rested while the other bull gathered up all the cows for himself. After thirty minutes, a cooler, rested Big Boy confidently challenged the other bull and after a brief fight claimed all the cows as his own.
Later that year I watched as Big Boy fought another bull and lost the uphill advantage. A bull learns early in his fighting career that when you are battling 1,600 pounds of determined power, it pays to be on the uphill side and use gravity to your advantage. As the fight progressed and Big Boy tired, he lost his footing during a clash and went down. With aggressive opponents, this can be a fatal mistake, and I fully expected to see a serious goring. But Big Boy kept perfectly still, barely breathing. His rival stood over him for a minute or two, but soon decided Big Boy was no longer a threat, and quickly walked off. Big Boy stayed down until the other bull was out of sight, then rose and calmly wandered away.
Biologists are taught that while moose and other animals are superbly adapted to their environments and learn many things that are necessary to survive, they don't make decisions. Instead, they rely greatly on instincts, patterned behaviors carried in their genes. After many years of observing moose it appears to me that they do make important decisions every day. They must decide where to go, what to eat, how to interact with other moose, how to cope with severe weather, and a host of other issues. In life or death situations I have watched them carefully assess options and make choices. Interacting often with bears and wolves, that constantly try to kill them, moose must decide whether to avoid or evade, stand or run, defend or not, and then execute these strategies given many different types of terrain, vegetation, and weather conditions, all of which require different choices at different times.
Big Boy showed me that moose do make important decisions, choices that affect their well-being and survival. Had he rushed right in (as other bulls might) against a well-rested, cooler opponent and immediately initiated a fight, the risk of losing would have been too great. Somehow he knew this. Had he struggled to regain his footing while down (as others would have), he would have been gored and injured. Better to remain motionless. Big Boy somehow made the right decisions. I'm convinced they involved more than just instinct.
During the time that Big Boy was in his prime, as I traveled to Denali for spring fieldwork, I always wondered if I would find him in good health. Winter is the critical time for moose as they struggle against deep snow that buries food and increases the costs of movement. Having not seen him for several months, I was a little worried that snow, cold, and hunger might have taken their toll and I would follow his radio signal to a pile of bones and hair. Or, maybe the ever-present wolves caught him in deep snow in a creek bottom, perhaps weakened from hunger or rutting injuries, and he lost the battle. But each spring my fears evaporated as I found him alive and well and starting to recuperate from winter.
One of my research colleagues spent portions of several winters at Denali trying to understand how moose cope with winter. He learned that older bulls like Big Boy segregate from younger bulls and cows and spend the winter in isolated, small valleys where their favorite foods grow lush and thick. Winter foods are typically willow shrubs that find moist conditions in the valleys ideal for growth. Certain valleys support older bulls every winter from November to April. During this time bulls shed their antlers, and these accumulate over the years in various stages of decomposition as rodents gnaw them and microorganisms soften the dense bone. The valley that Big Boy liked had many such antlers-they stood out from the air as I flew over the valley counting moose. In addition to rutting behavior, we were studying antler size, composition and structure, and I vowed to visit this valley in spring to examine sheds and obtain data.
On a bright spring morning after snowmelt and before greenup, I walked up the narrow valley and spent a pleasant day searching for antlers near the rushing stream. In the willows, several species of songbirds were busy laying out territories and getting ready to raise their young. By mid-morning I had found about a dozen sheds. Suddenly, I saw a large antler at the base of a spruce tree and instantly recognized it as Big Boy's. Later examination of photographs from the previous fall proved me correct. The rodents had not found it and the snow cover prevented the sun from bleaching it so it looked just as it did when Big Boy wore it. I found where several chips were missing from a few tines as a result of fights, and the antler still had the faint odor of the rut. I put it and several others on a pack frame and carried them back for more analysis, but the antler had more value to me than just as a scientific specimen. It was a part of Big Boy and I treasured it.
By spring, large bull moose have lost about twenty percent or more of their fall body weight from a combination of rutting and the long winter. They stop eating for three weeks during the rut. As a result, the pounds melt away and they enter the winter much thinner than cows that feed throughout the rut. As snow buries forage, moose are left with coarse, fibrous twigs that provide poor nutrition, comparable to humans trying to survive only on a diet of corn flakes. How glad moose must be to finally experience spring, to watch the snow melt, and to suddenly have green, nutritious forage in abundance and variety as new leaves sprout!
Big Boy would spend each summer in a home range of about fifteen square miles that met all his needs. He spent the vast majority of his time feeding, resting, and moving from place to place. In summer moose process enormous quantities of food, extracting energy for growth, fat storage, replacement of their coats, and the production of antlers. For a moose like Big Boy that meant growing a large set of antlers weighing perhaps sixty pounds. All of the calcium and phosphorous required would come from plants in his diet, with about one-half of the total antler growth achieved during the month of June. It also meant laying down about 200 or more pounds of fat from early June to late August before the first frosts spoiled the banquet.
Biologists have concluded that summer nutrition is likely more important than winter nutrition for moose as during summer they acquire the energy stores needed to last the rest of the year. Thus, to be successful, bulls like Big Boy must be good feeders as well as good fighters. They cannot afford to select home ranges or feeding sites with few nutritious plants, or to waste time and energy moving a lot. Nor can they burn up valuable energy interacting much with other moose. By the start of the rut, Big Boy was always fat with large, strong antlers, due largely to the good choices he made during summer.
By mid-August when I traveled north to begin fall fieldwork each year, there was already a hint of fall color on the tundra. Some years it snowed before the leaves turned. Autumn in Denali means foggy, damp days followed by bright blue skies, Sandhill Crane migrations, cold nights with heavy morning frosts, brilliant red bearberry leaves, heavy blueberry and cranberry crops, and the promise of winter that could come within a month. But for me, autumn meant the moose rut was at hand.
Winter for moose mostly involves surviving, and summer is mainly for feeding, but fall is for mating. Moose are often solitary during much of the year. At times they avoid other moose or are aggressive when they do encounter them. They mainly associate with others when they happen to jointly occupy patches of good habitat. Then, there is very little social behavior and no interest at all in sex. The reproductive systems of bulls are totally shut down for about eight months each year. But in late summer moose begin to associate much more, hormones are turned back on, and bulls go through the human equivalent of puberty, not once in a lifetime, but annually.
The rut begins with the shedding of antler "velvet," the dark skin that covers antlers during growth. Starting about August 25th, bulls rub and scrape velvet from their antlers in a process that lasts less than a day and results in bloodstained, hard, white weapons of bone. The largest bulls shed velvet first with yearlings shedding last. By September 10th all are velvet-free.
Mating starts about September 25th so there is a full month of pre-rutting activity that involves numerous behaviors seen only at this time of year. Bulls thrash antlers against shrubs and trees thereby advertising their presence to others. They also advertise by "croaking," a gulping vocalization that can be heard over long distances. Then, there are rutting pits, shallow depressions that bulls dig and into which they urinate. Cows and bulls wallow in the mud-urine mixture to label themselves with chemicals found in the bulls' urine. Throughout this period, bulls sort out their dominance hierarchy and by mid-September the top bulls have collected groups of cows that will stay in the same general areas until mating is complete.
After Big Boy reached his prime I selected him and his group as the focus of my rutting observations. He held the largest group of cows in the area so my time there was well spent as cows came and left and a constant parade of challenger bulls passed by. Each day we arose early and took the one-hour hike to his rutting area. Some years there was a foot of snow and ten degree temperatures during the peak of the rut; other years had shirtsleeve weather in early October. Once there, we located the radio-collared animals, counted all the moose in the group and around the fringes, and spent the day recording the occurrence and frequency of all the behaviors we could see. After a time, recording numerous instances of common behaviors became tedious, but this was soon forgotten when Big Boy and one of his rivals decided to fight.
Because the rutting group was often spread out over a large area, typically in dense spruce forest, and because we focused at times on behavior of radio-collared cows, the first hint of a fight often was the sound of a tremendous clash of antlers. My colleagues and I and perhaps a photographer or two would then run there to see the spectacle. My job was to stay close enough to record the behaviors, determine the outcome, and note things like instances of broken antlers, all without being too close to risk being run over accidentally. The moose were totally engrossed with each other and ignored their human audience.
During the three years that Big Boy was about nine to eleven years old he was the only bull we studied that was able to hold a rutting group during the entire mating season each year. Other bulls might hold a group only a day or two before being defeated by a rival, or might hold on until intense rutting activity drained their energy or robbed their confidence. We calculated that from beginning to end, Big Boy might have fought as many as 20 battles per year with perhaps three or four of those being epoch contests that severely tested his endurance. This was a remarkable achievement, comparable to a human boxer winning several championship bouts during a two-week period without suffering major injuries.
While other bulls like Chip and Buddy might only mate with two or three cows a year, Big Boy reaped the rewards of his efficient summer feeding, his good choice of winter habitat, his superior genes, and his exceptional fighting ability by mating with up to twenty-five females each year. Over his lifetime his success was measured by leaving behind many more descendants than lesser bulls despite the high mortality of calves. Each year since his reign, I have looked carefully at all the bulls and cows that now inhabit his old territory, wondering how many carry his genes. And I wonder if any of them, as individuals, will match his remarkable success.
When I first saw Big Boy in early September of what was to be his last year, I knew that he was declining. He wasn't as fat as in recent years, his antlers were less massive, and he was stiff, perhaps from arthritis in his hips or back. But things that year progressed right on schedule during the rut with Big Boy gathering a large group of cows in the same area where he had held court for several years. Despite his decline he was still the "baddest" moose in the area. Perhaps most of the other bulls didn't even try to challenge him, remembering the results of challenges in prior years. As the peak of the rut approached, I assumed that Big Boy would make it through his fourth year of being undefeated.
As a television cameraman and I walked to the rutting grounds on a cold October morning I thought we would find things as we left them the night before. But a new bull was in charge of the cows that morning and Big Boy was nowhere in sight. I was so confident in Big Boy that I left my radio receiver behind and searched for him solely by sight. When I found him nearby he had obviously been in a fight, although he was lying down and the extent of his injuries was not apparent. Only when he tried to stand did I realize how serious it was. One or both .of his rear legs were severely injured and he couldn't walk. I stayed with him for about two hours when suddenly the new bull arrived and gored him again, on the ground. A bull like this has no defense and is at the mercy of his rival. This time, his rival was merciless.
When we left that night, Big Boy was still alive but couldn't lift his head. I knew it was the last time I would see him alive, so before we left I spent a few minutes with him thinking about all the days we spent together and how much I learned. I told him he was a hell of a moose and wished him well in his next life.
Surely, Big Boy knew he was old and not as strong as he had been. He definitely knew he could back down from his last fight -- the rules of moose fighting provide room for a quick exit. Had he exited, he likely would have lived another year or two, dying at last from starvation or wolves, a fall through the ice, or perhaps a lingering infection. But Big Boy did not quit. How could he? He was a warrior to the end, and most warriors die by the sword. They really have little choice.
Two years after he died, on the anniversary of his death, I went back for a final visit. Daylight was fading fast and I had a long hike back to my truck, but I stayed a while. There remained a few bleached bones along with the skull and antlers. The porcupines and hares had reduced the antlers somewhat, but their massive bulk was still apparent. A light snowfall covered them and a red fox had left a few paw prints on one antler palm. I'd like to think that the old skull is still there proving that Big Boy once lived, but I don't plan to go check. I don't want to risk finding nothing.