Owls Aren't Wise and Bats Aren't Blind (38 page)

A New Englander unfamiliar with park bears and their ways, he made the mistake of leaving his car door open when he went into the office to talk with the ranger. As he emerged from the ranger station, he saw a hefty black bear in the front seat, industriously rummaging through his lunch on the back seat. Just at that moment, the bear leaned back and pressed against the horn button. The horn beeped loudly, and disaster swiftly ensued, for the alarmed bear catapulted itself straight through the canvas roof of the car and disappeared into the nearby forest!

As more and more cities and suburbs spill out into surrounding bear habitat, an increasing number of people are having conflicts with black bears. Colorado alone has recorded some 450 incidents involving bears and humans during the past year—and most of those have been in urban and suburban settings. Like park bears, these bruins have lost much of their fear of humans and scavenge for garbage, try to break into homes, and otherwise cause serious problems. Although few individuals are actually killed in these encounters, they’re sometimes attacked and mauled.

Attacks on humans by truly wild black bears are extremely rare, but a mother bear with cubs can be exceedingly dangerous. Just two or three years ago, a Vermont farmer was attacked by a bear with a cub when he went out in late spring to check his maple sugar woods. When the bear charged him, the farmer hastily climbed a tree. But even though the cub had gone up another tree and was out of danger, the mother nonetheless came up the tree after the farmer.

Black bears are excellent tree climbers, and this one was no exception. Up the tree she came after the farmer, who defended himself by vigorously kicking the female bear—called a sow—in the nose and face, while she bit at his boot. Finally he inflicted enough damage so that the sow backed down, called her cub, and disappeared into the surrounding woods.

The farmer climbed down after what seemed a prudent interval, but the sow, who was only in hiding nearby, immediately rushed him and renewed the attack. Again the farmer climbed the tree and fought her off. When she finally climbed down and disappeared for the second time, the farmer wisely decided to remain where he was. After two or three more hours, some of his family came looking for him, and by that time the bear had departed. While sustained attacks like this are rare, even by a sow with cubs, it does serve to show why a bear with cubs should be avoided at all costs.

Bears are usually regarded as primarily meat eaters, and they’re indeed carnivores, but the vast majority of a black bear’s diet consists of plant food, from a variety of early spring greens to berries, apples, beechnuts, acorns, and corn in the fall. While all of these are important in their season, the early-spring greens are the most critical for black bears: just emerging from hibernation, the bears require the nutrients that these plants supply. Upland wetlands, where the snow melts early and green plants poke up through the ground while surrounding areas are still snow-covered, are therefore a vital part of good black bear habitat.

As already noted, black bears can zip up and down a tree with great rapidity. In the fall they climb beech trees in search of the highly nutritious beechnuts, which they’re exceedingly fond of, and the parallel claw marks that they leave on the smooth, silvery beech bark are clear evidence that bears have been there. Bears also make so-called “bears’ nests” in beech trees, although these aren’t actually nests. A bear sits in one spot high in the beech tree and reaches out to pull nut-laden branches toward itself. Many branches and twigs are partially broken in the process, for bears are extremely powerful. The result is a tangle of branches that, from the ground, somewhat resembles a huge nest.

Meat sources for black bears are usually somewhat limited. They include fawns in the spring, ants and grubs, and mice and squirrels whenever a bear can dig them out. Frogs and fish are also fair game, and carrion and garbage, when available, are also part of their diet. Bears have a reputation for possessing a great sweet tooth, but they may actually rip open domestic hives and bee trees more for the bees and their larvae than for the honey.

One of the hoarier myths about black bears is that they can’t run uphill very well because their hind legs are short, so anyone being chased by a bear should try to escape by racing up a steep slope. Another version holds exactly the opposite to be the case: black bears can’t run fast
downhill,
because their hind legs are so short! How these notions ever originated is anyone’s guess, but they’ve been around for a very long time. In any event, both versions are emphatically untrue. Uphill, downhill, sidehill, or on the level, a bear can outrun a person with ease. Although bears aren’t long-distance runners, for short distances they can sprint astonishingly fast for what might seem a rolypoly creature. Their top speed is at least thirty miles an hour and probably more—almost as fast as a white-tailed deer can run!

Another great myth about black bears is that they hoot almost like owls. This particular myth seems to be confined to portions of northern New England, especially Vermont, since biologists in other parts of the United States have never heard of it. For years I was told repeatedly that black bears hoot, and I was puzzled and disturbed by my apparent inability to tell which hoots belonged to barred owls and which to black bears. When I inquired of this person or that about how one could differentiate between the hoots of the two, I always received answers that were substantially the same: “They sound a lot alike, but you can hear the difference if you really listen carefully.”

I listened carefully, over and over, but no matter how hard I tried, they all sounded like barred owls to me. Then one day I was discussing wildlife myths with Charles Willey, who was the bear biologist for the Vermont Fish and Wildlife Department at that time. “There’s one myth I hope you can correct,” Charlie told me, “and that’s the one that bears hoot.”

“You mean that they don’t?” I asked him in surprise and not a little relief. He informed me that no reputable biologist or scientist, even those who have worked closely with hundreds of black bears over many years, has ever heard or seen a bear hoot. Black bears make a wide variety of sounds—growls, whines, grunts, rumbles, snorts, woofs, and whuffles among them—but they don’t hoot!

Trying to disabuse people of this conviction, however, is a nearly hopeless task. Most who believe this myth embrace it with an almost religious fervor, and utterly refuse to listen to contrary opinions. For example, an acquaintance of mine who’s a noted ornithologist told me about emerging from his car at a friend’s house, just as a barred owl hooted close by. “That’s a bear,” said his host excitedly. When the ornithologist demurred and identified the hooter as a barred owl, the host flatly refused to believe him!

Charlie Willey also told me an amusing and instructive anecdote concerning a college student from Vermont who was Charlie’s assistant one summer. In the course of their work with bears, Charlie mentioned that bears don’t hoot. The young man, who had been raised on this fiction, was somewhat skeptical at first, but finally appeared convinced that Charlie was right. Then he went home for the weekend and returned on Monday to tell Charlie with great excitement that bears really
do
hoot. It seems that he had gone into the woods with an old hunter and woodsman, and at some point they had heard a bear hoot.

“But how do you know it was a bear?” Charlie asked him.

“Because he told me so,” responded his assistant. This reply was remarkably similar to that of Josephine in Gilbert and Sullivan’s HMS Pinafore: “But I know Sir Joseph is a good and great man—for he told me so himself.”

Like the brown and polar bears, black bears have delayed implantation of the embryo. Although mating occurs in the summer, the fertile eggs don’t implant and begin to develop inside the female until late fall. This is an evolutionary adaptation that makes great sense. In years when food is very scarce before hibernation, cubs might sap the mother’s strength so that both mother and cubs would perish. Under this regimen, the embryos simply don’t implant if the female hasn’t fattened sufficiently for hibernation, thus ensuring her survival to breed another year.

As the rich foods of late summer and early autumn mature, bears accelerate the pace of their feeding in a race to accumulate sufficient fat to see them through the winter. Now, in addition to the usual plant foods, insects, and small rodents, the bruins eagerly seek foods such as acorns, beechnuts, apples, and corn. At this season of the year they can be especially destructive to farmers and orchardists. For that reason, bear hunting seasons often open in time to reduce or eliminate some of the damage caused by bears, especially sows with yearling cubs. As one biologist explained it, “A family of bears in a farmer’s cornfield makes it look as if someone had driven a Mack truck around and around in the corn.”

As winter draws near, black bears seek a den for hibernation. Although bears are commonly thought to dwell in caves and hibernate there, they don’t need or use shelter during the warm months, and there are far too few caves to meet the bears’ winter needs. Most black bears in northern regions hibernate beneath the roots of a blown-down tree, in a hollow in the ground, in a huge hollow tree, in a fox or coyote den that they’ve enlarged, or in some similarly sheltered place. In areas where summer cottages are abundant, such as parts of New York’s Catskill Mountains, bears often den beneath porches or in crawl spaces under the uninhabited buildings. The human occupants leave well before the bears den in late autumn, and the bears depart in the spring before the humans return. It’s a fine situation for the bears.

Where cold isn’t extreme, black bears even build huge nests for winter quarters. These are nothing like the so-called “bears’ nests” in beech trees; instead, they’re constructed on the ground—great, dish-shaped circles of grass and leaves not unlike huge birds’ nests. Once this edifice is complete, the bear curls up in it for the winter. Still farther south, bears may become torpid for a time, but don’t have a winter den.

Denning time varies greatly, depending on the food supply rather than on the weather. In years when food is scarce, they’ll den quite early. When good food is abundant, however, bears will keep on foraging for several more weeks, going into hibernation only when driven to it by severe winter weather.

In January or February the mother black bear gives birth to tiny cubs, usually two or three, which weigh only one-half to three-quarters of a pound. As with kittens, their eyes are closed at first and don’t open for nearly a month.

A major misunderstanding is the belief that the female bear sleeps through the birth of the cubs, nurses them in her sleep, and wakes up in the spring to learn for the first time that—wonder of wonders—she has babies. The truth is that bears den, but don’t hibernate in the strict technical sense of that word. In true hibernators, both heartbeat and body temperature drop dramatically; the temperature of denning bears doesn’t drop during what we normally refer to as their hibernation period.

All of this means that bears don’t go into a comatose state of true hibernation similar to that of the woodchuck. Instead they awaken frequently, move about in the den, and occasionally even emerge for short periods. In any event, the female is very much aware of her cubs, and takes good care of them in the den. She cuts their umbilical cords, nurses them, and is careful not to roll on them and crush them.

Despite the fact that they aren’t true hibernators, bears have a complex assortment of wondrous adaptations to see them through the winter. For example, a bear’s heartbeat slows to eight beats per minute for much of the time while it’s denning. Moreover, it doesn’t drink during that time, and “eats” only by consuming its own fat. Meanwhile, it neither urinates nor defecates until it leaves the den in the spring.

The cubs grow rapidly, for their mother’s milk is extremely rich. To put this richness in perspective, consider that a black bear’s milk contains at least 24 percent fat, while cows and humans produce milk with roughly 4.5 percent fat. It’s no wonder that cubs thrive on such high-energy fare while still restricted to their den.

A thin mother and usually lively, well-fed youngsters emerge from their den in early spring. Black bears only breed every other year, so the cubs remain with their mother for a year and a half, learning how to fend for themselves. Finally, during the summer of their second year, the cubs set out on their own.

Mortality is very high among cubs during their first spring and summer— usually 50 percent or more. In areas where food is apt to be scarce in the spring, cubs often starve, but it also appears that other bears, especially males, kill many cubs. In one Arizona study, older bears killed half of the cubs that died from identifiable causes. In such cases the older bear also frequently eats the cub.

It’s generally assumed that older, larger females will fight off males in order to protect their cubs, but that small, young, and inexperienced mothers aren’t up to the task of driving off a much bigger male. This behavior is very difficult to document, however, since black bears are so elusive and their actions are generally concealed by forest growth.

Why would bears kill cubs of their own species? There are two plausible— though unproven—reasons. The first is that male bears can somehow identify their own offspring and kill only the cubs fathered by other males. This makes evolutionary sense, since the male is helping to ensure that, by eliminating a rival’s cubs, its own genes will be those passed down through the population.

The second possible reason is that a female bear comes into heat within forty-eight hours after she stops nursing, following the loss of her cubs. The act of killing cubs thus presents the male with a double benefit: he has eliminated a rival’s cubs, and he can now impregnate the female himself.

Black bears are extremely wary and difficult to see in the wild. Their rather poor eyesight is compensated for by marvelous hearing and sense of smell, and they use those faculties to avoid humans whenever possible. Consequently, many people who have spent a great deal of time in the woods, even in good bear habitat, have never seen a single truly wild bear. Our family has been extremely fortunate in this regard, for we’ve seen several bears on or very close to our land, as well as two thoroughly wild bears elsewhere. Two of these incidents were especially interesting.