Bear basics

[oldgreengrolar]

Ecologists Get To The Bottom Of Why Bears Rub Trees - September 11, 2007.

www.sciencedaily.com/releases/2007/09/070909221303.htm

Ecologists have at last got to the bottom of why bears rub trees – and it's not because they have itchy backs. Speaking at the British Ecological Society's Annual Meeting in Glasgow the week of September 10, Dr Owen Nevin of the University of Cumbria will reveal that adult male grizzly bears use so-called “rub trees” as a way to communicate with each other while looking for breeding females, and that this behaviour could help reduce battles between the bears.

Many theories have been advanced as to why bears rub trees: some thought females might rub trees as they came into oestrous, and others that bears might be giving their backs a good scratch to get rid of parasites or pick up sap to act as insect repellent. Until now these ideas have been extremely difficult to test because bears usually live at low densities and rubbing is relatively rare behaviour.

Because bears use the same rub trees for generations, and because he has logged rub trees over almost a decade working on bears in British Columbia in Canada, Nevin has been able to gain a unique insight into grizzlies' behaviour. Over the past two years, he used four digital cameras with infra-red trips set up opposite rub trees to collect data on which bears used the trees and when. He coupled this with satellite telemetry equipment to track individual bears' movements.

“The cameras show that adult male bears are the most likely to rub trees, and the satellite telemetry tells us that males move from valley to valley in large loops, marking trees as they go, while looking for breeding females,” Nevin says.

Nevin believes that by marking trees, adult males may be getting to know each other better, and that this scent familiarity could act as a way of reducing fighting among adult male bears. According to Nevin: “Big male bears can seriously injure and even kill each other when they get into a fight. If one recognises the other from the scent marks on the rub trees in the area he knows he’s in for a tough fight - he’s on the other guy’s patch so to speak - so it might be better to back away than make a serious challenge.”

Like other species, male bears will sometimes kill a female’s offspring to get a chance to mate with her; scientists refer to this as sexually-selected infanticide. Nevin’s work suggests that very young bears may be using the rub trees to help them trick potentially killer males.

“It’s really hard to document, but on several occasions the cameras caught cubs who are being chased away from their mother by a large male visiting and rubbing on trees which he has marked. They can visit the tree two or three times in a day, sometimes within an hour of the big male, so it may be that smelling like him makes them safer – related animals smell similar and animals are less aggressive towards relatives,” Nevin says.

As well as improving our understanding of how bears communicate, the results should also help improve bear conservation by affording an insight into the behaviour of secretive male bears. Earlier work in Canada and Alaska has shown that tourist activities can change how adult male bears behave during the autumn salmon-feeding season, which has been the focus of eco-tourism, but spring viewing when the bears are breeding is becoming increasingly popular.

According to Nevin: “Understanding normal behaviour has to be the starting point for managing bear populations and our activities around them. It doesn’t matter whether we’re considering impacts of tourism or sport hunting on these dense North American populations or reintroductions and enhancements in threatened European populations: knowing how these animals interact with each other will help us to make the right decisions.”

Dr Nevin will present his findings on Monday 10 September 2007 at the British Ecological Society Annual Meeting.

[oldgreengrolar]

shaggygod.proboards.com/thread/1015/bears-brief-history-bernd-brunner

Bears – A Brief History, by Bernd Brunner

Most scientists today recognize eight species of bears worldwide.

All living bears today have descended from a common ancestor known as Ursavus, or “dawn bear.” This animal, which lived about twenty million years ago, was about the size of a small terrier. Even at this early point in evolutionary history, however, Ursavus had a jaw already markedly different from that of a dog. Over time, groups of this early bear species split off and wandered into different habitats, where they adapted to new and better environments and to available sources of food. Each group underwent its own course of evolution.

Throughout human history, each scientist could base his classification scheme only on the limited knowledge he possessed at a particular point in time.

Armed with a magnifying glass, he (Merriam Webster), he painstakingly investigated every bear tooth and skull in the Museum of Natural History in Washington, D.C. Merriam proceeded to subdivide Ursus horribilis into no less than eighty-six separate subspecies. … (he) firmly believed that ‘it is not the business of the naturalist to either create of suppress subspecies, but to endeavour to ascertain how many Nature has established.’ Merriam’s classification scheme, however, has not withstood the test of time; it has come to be recognised as a classic example of taxonomic over-splitting. Today the names Ursus horribilis and Ursus arctos horribilis are used only rarely; they remind us of how this animal was demonized and driven to extinction in many parts of North America.

(On Christian bear legends) Other saints, such as the missionary Korbinian, demonstrated their power by taming bears. After a wild bear killed his horse during a pilgrimage to Rome, the saint loaded his possessions on the bear’s back as punishment and continued on his way. Once he reached Rome, the holy man released the bear from servitude.

The many surviving stories about bears reveal the variety of roles that they have played in the human imagination, from enemies of mankind to their protective spirits. One of the most prominent and persistent threads of such tales is the assumption that bears and humans are intimately related. While this kinship sometimes appears to be merely symbolic, at other times once can sense a genuine belief underlying such accounts that bears are our not-so-distant relatives. From out modern perspective, of course, this distinction belongs to the apes.

Other stories about bearlike humans come from Scandinavia. Legends relate that after the founding of the Norwegian kingdom more than a thousand years ago, an army of especially strong men was called into being. These fearsome warriors, or ‘berserkers’, dedicated their lives to the supreme god Wotan, also known as Odin. The word ‘berserker’ is presumably a combination of ‘beri’, Old Norse for ‘bear’, and ‘serkr’, for ‘shirt’, and thus literally means ‘clothed as a bear’. According to ancient Germanic texts, berserkers were indistinguishable from ordinary men in normal circumstances, but when they were aroused they could perform incredible feats such as ripping the rim of a shield with their teeth, swallowing glowing coals, or walking through blazing fire. Heidrek’s Saga relates that the twelve berserkers who were the brothers and sons of Arngrim of Holm possessed swords, forged by dwarves, that they wielded not only in battle but also, apparently in the grip of delusions, against trees and rocks.

An ordinary mortal had little chance when faced with an angry berserker, but there was one way to prevent the worst: before an outburst, a berserker would briefly become drowsy, providing a momentary opportunity to tie him up. A variety of triggers could prompt a berserker to go ‘berserk’, including the approach of darkness, strong emotions such as wrath or belligerence, intense pain, the taste of raw meat, or in the case of the Icelander Odd, the sight of blood. After his father and brother were killed by a polar bear, Odd beat the bear to death. From this point on, Odd was a classic berseker: irascible, unsociable, and tremendously strong.

Another legend relates that a seer once observed the berserkers Dufthak and Storolf as they fought at sundown in the forms of a bear and a bull. The next morning a desolate crater marked the location of their struggle.

As late as the eleventh century, there were still aristocrats who considered themselves to be descended from bears.

Some illustrations produced hundreds of years ago resemble mythica beings more than the real-life creatures they are meant to represent.

The theories of early nature writers about bears … could be extremely creative. As French scientist Georges Buffon was compelled to complain, “Among at least the generally known animals, there is none which the claims of researchers diverge so greatly as the bear.’

… up to five months can pass before the fertilized egg attaches itself to the wall of the uterus – a process that tales only three of four days in humans – and only then develops into a bear cub. Scientists call this phenomenon, regulated by the hormonal processes, ‘delayed implantation.’ If the bear does not find enough food in the fall, hormonal processes cause the egg to be reabsorbed, thereby preventing the cubs’ birth.

Pliny further claimed that the soles of the bears’ paws contain a great deal of fat, which the animals consume – in other words, that bears have the ability to eat from their own bodies. … In actuality, the skin on bear paws regenerates during hibernation. Bears tend to audibly suck and chew on their paws during this time, probably an attempt to soothe the resulting itching or discomfort.

Lorenz Oken of Germany, first a doctor and then a natural scientist, set out in the 1830s to ‘compare and report on everything ever observed about the life and behaviour of animals and written in travelogues and newspapers since the earliest days.’ This monumental effort, according to Oken, consisted of unmasking ‘false citations’, reading ‘a lot of useless nonsense,’ and comparing ‘a great number of bad and thoughtless illustrations. He considered bears to be not particularly aggressive because they attack people only if provoked. The bear, Oken reported, ‘leads an unhappy, quiet, and lonely life and only associates with the female during the mating season.

..humans developed astounding explanations to account for hibernation. Swiss naturalist Conrad Gessner (1516-1565), for example, seemed to rely in good faith on the unlikely report of a Swiss goatherd. One day in the late fall, the man claimed, as he left his hut with a cheese pot on his head, he saw a bear in the distance pick a plant and eat it. After the bear had left the area the goatherd tasted the same plant himself, immediately lay down on the path, covered his head with the pot, and, despite the winter cold, slept until the onset of spring. Once a bear selects a suitable cave for his retreat, Gessner claimed, he backs into it as lightly as possible ‘so that the hunters do not come across his tracks.’

Physician Adolph W. Otto shared Prunelle’s view. He reported that he had kept a bear captive in a dark location in order to be able to observe him closely. When the bear was asleep he could be easily awakened, and Otto described him as weak and despondent debilis et morosus) rather than sleepy. That his experiment had nothing to do with a bear’s natural behaviour does not seem to have troubled the good doctor. He could not know that captive bears simply don’t hibernate.

Today we know more: brown bears spend three to four months in the winter in a resting state, which can be understood to be a less extreme form of genuine hibernation. In this way their winter habits differ from those of dormice or hedgehogs, who sleep uninterrupted for a long period each winter and thus truly hibernate. During this period of rest, the bear’s pulse slows and its body temperature drops by about two and a half degrees. Winter is an arduous time for bears: foraging for food is extremely difficult, made all the more so by their relatively short legs, which are not suited to wading through the snow. Entering a sleeplike state allows them to bypass the challenging winter. They prepare for this period of inactivity by accumulating far during the months when food is plentiful.

Giovanni Batista della Porta (1535-1615), an Italian naturalist and one of the first scientists in the modern sense, classified various human types according to the animals they supposedly resembled. … The ‘worst possible human characteristic of all’ was, for della Porta, the thoroughly bestial, ‘godforsaken idiot.’ This personality is revealed by dark eyes, a large belly, and mouth that is ‘so long and wide … that the face seems split in two.’ Such an individual resembles the ‘ferocious bear,’ whom della Porta condemned as stupid, scheming, dangerous, treacherous, and, as if this were not enough, ‘wilder than all other animals,’ thus uniting lack of intelligence with cruelty and coarseness in one unlikable package.

Swiss science author Peter Scheitlin (1779-1848), one of the forerunners of the animal-rights movement, viewed the bear, which he considered to be ‘a most remarkable animal’, as a thoroughly good-natured creature … ‘He is known to have approached young girls hunting for strawberries and stolen the fruit right from their baskets, and then went on his way – we can almost dare to say – laughing on his way,’ he wrote.

Roosevelt added that a wounded or cornered animal ‘will attack his foes with a headlong, reckless fury that renders him one of the most dangerous of the wild beasts.

For Tschudi (1820-1886), the bear had ‘a direct, open character free of cunning and deceit.’ The bear is far from harmless, however: ‘What the fox obtains with his wits and the eagle with his swiftness, the bear pursues with undisguised force.’

Zoology professor Gustav Jaeger was of the opinion that the bear represented a ‘kaleidoscopic’ figure like few other animals – and he did not intend this characterization as a compliment. Like the lion and the tiger, the bear can bring down the largest of mammals, yet it poaches the fields ‘like any mere ruminating beast’. It steals from orchards ‘like a monkey,’ eats berries from the stem ‘like a blackbird’, climbs after pinecones ‘like a squirrel’, plunders beehives and anthills ‘like a woodpecker,’ digs for maggots ‘like a pig’ and, finally, fishes and crabs ‘like an otter.’

Bears seem to like to travel in the footsteps of other bears: Russian bear researcher Aleksander Fyodorovich Middendorf (1815-1894) discovered a chain of such imprints stretching over hundreds of miles.

… it was once popular to take in bear cubs whose mothers had been killed in the hunt. People in the eighteenth and nineteenth centuries seemed to have enjoyed the company of these amusing, fur-covered, wild ‘little people’ …

… accounts not only demonstrate that people and bear cubs have had astoundingly close relationships, they also reveal the limits of this intimacy. In 1857 for example, German professor Johann H.Blasius wrote that ‘bear cubs are easily tamed. They remain quite harmless until they are grown and become entirely used to their environment. Once they reach the age of four, however, they acquire a grimmer character, and those friendly relationships are usually destroyed by a violent outburst by the bear’s true nature.’

Once animals are truly domesticated, certain behavioural traits manifest themselves in their genes. Captive and seemingly ‘tame’ bears have never undergone this transformation. For evolutionary biologist Jared Diamond, the European brown bear’s ‘nasty disposition’ explains why this animal is ‘perhaps the most unlikely pet’.

… most Native American cultures sympathised with the animals they hunted. European settlers, however, were not burdened with such respectful attitudes toward their prey. The chase for grizzlies in the nineteenth century unfolded at breakneck speed…

… and when these settlers began raising cattle and farm stock their already negative perspective on bears took a dramatic turn for the worse. In Texas, for example, the number of cattle multiplied from one hundred thousand in 1830 to more than three and half million by 1860. This development was bad news for the abundant grizzly population – because the bears posed a dangerous risk to the valuable stock, killing them was considered good for business. … The introduction of high-powered repeating rifles further increased the number of bear hunters. Many of America’s plentiful bear populations were wiped out… …nowhere else have bears been wiped out in such a short amount of time.

The tragic accident that befell Adolf Cossmy (born ‘Kossmeyer’) in the mid-1930s, however, shows that handling large predators, however trusted and seemingly ‘tame,’ can still be a lethal undertaking. Cossmy, who as a young man travelled the world with groups of bears and lions, often approached his bears ‘naked’ – that is, without a whip and fork. His favourite animal was a large polar bear that sometimes posed as a model for artists. Cossmy had the unusual habit of giving the bear a kiss whenever it’s work was completed. Ironically enough, this beloved bear would be the end of him. One morning, as he was lathering and scrubbing the animal, he stumbled over an empty can, whereupon the startled bear flung himself upon its trainer and killed him.

Many if not most humans in the world today no longer understand what it means to live with bears. When a bear does risk proximity to humans, its presence is often interpreted either as a threat to life and property or as a sensation – or both. People, especially in densely populated areas, may react to bears in their midst with an excessive, irrational fear that amounts to veritable ‘bearnoia’. Japan offers a poignant example. We would normally expect that, to avert danger to man and beast alike, the driver of a full bus would hit the brakes if he saw a bear on the road. But in May 1958 near Furanocho, something very different occurred: the driver sped up – and the passengers encouraged him to do it. The poor bear was forced over a cliff and plummeted to its death.

Our fascination with bears also makes it difficult for us to recognize that, no matter how familiar their glance and gait may seem, bears are not interested in people. But indifference on their part should not prevent us from feeling admiration, respectful curiosity, and concern for the bears that share our world. I would like to have faith in our ability to devise intelligent ways for humans and bears to coexist - although I hope this book has made it clear that we should also keep a respectful distance from them. Since completely avoiding misanthromorphism may be impossible, perhaps we can think and speak of bears as our distant relatives in the forest who have their own way of doing things and simply prefer to keep to themselves. Let us not be disappointed - the bears cannot help it. We can avoid clashes with bears only if we learn to stay out of their way. Anything else is the stuff of dreams!