The most immediate and topically recognized threats to the polar bear are the drastic changes taking place in their natural habitat, which is literally melting away due to global warming. The United States Geological Survey, for example, in November 2006, stated that the loss of sea ice in the Alaskan portion of the Beaufort Sea has lead to a higher death rate for polar bear cubs.
The Harvard University Gazette said:
A 1999 study of polar bears on Hudson Bay showed that rising temperatures are thinning the pack ice from which the bears hunt, driving them to shore weeks before they've caught enough food to get them through hibernation.
The BBC reported:
Climate change is threatening polar bears with starvation by shortening their hunting season, according to a study by scientists from the Canadian Wildlife Service.
There is also some concern over pollution in addition to the normal natural problems the bears might face. Reduced cub survival has been reported in connection with PCBs, as well as reports of organochlorines affecting the endocrine system and immune systems with lower immunoglobulin G seen with increasing PCB levels.
The lipophilic PCBs are considered a serious threat to marine mammals generally and to their food web, quickly concentrating into fat and blubber. These and related compounds are known in mammals (including humans) to cause such things as abortion, still births, alteration of the menstrual cycle, poor growth and survival of young, carcinogenicity, immunotoxicity, and even outright lethality. Other classes of organohalogens have been found in polar bears, such as PCDDs, PCDFs, TCPMe and TCPMeOH. Hermaphroditic polar bears have now been observed in less pristine areas. While some countries now ban some of these substances, they are still produced in others, and still end up all over the entire planet including the formerly pristine arctic. Even after the use of these chemicals is stopped, they continue to accumulate up the food chain, including in marine mammals and humans, for some time to come.
The bears sometimes have problems with various skin diseases with dermatitis caused sometimes by mites or other parasites. The bears are especially susceptible to Trichinella, a parasitic roundworm they contract by eating infected seals. Sometimes excess heavy metals have been observed, as well as ethylene glycol (antifreeze) poisoning. Bears exposed to oil and petroleum products lose the insulative integrity of their coats, forcing metabolic rates to dramatically increase to maintain body heat in their challenging environment. Bacterial Leptospirosis, rabies and morbillivirus have been recorded. Interestingly, the bears are thought by some to be more resistant than other carnivores to viral disease. The pollutant effect on the bears' immune systems, however, may end up decreasing their ability to cope with the naturally present immunological threats it encounters, and in such a challenging habitat even minor weaknesses can lead to serious problems and quick death.
Friday, June 15, 2007
Tuesday, June 12, 2007
Monday, June 11, 2007
Knut Chasing Ducks and Squirrels
Knut, Berlin Zoo's fast-growing star polar bear cub, isn't just biting his keeper, he has also been chasing ducks and squirrels and taking a disturbing interest in some of the zoo's cranes.
Polar bear cub celebrity Knut has been honing his hunting skills by chasing ducks and squirrels in Berlin Zoo but so far hasn't caught any thanks to the quick intervention of his handlers.
"Some ducks landed in the moat around his enclosure but he couldn't get to them because we got there first," the zoo's bear expert, Heiner Klös, told SPIEGEL ONLINE.
"He's also been showing an interest in squirrels during his morning walks around the zoo." Each day before the zoo opens, Knut goes for a stroll past the cages and enclosures with his keeper Thomas Dörflein, who taught him how to swim last month.
Past strolls have brought him face-to-face -- separated by powerful glass -- with his mother Tosca, who rejected the cub at birth and would probably devour him if she could.
"He has also been interested in the cranes but they were behind a fence," said Klös.
The polar bear cub celebrity, now over 30 kilos (66 pounds), is gradually being weaned off his "mother" Dörflein who hand-reared him, and has been given his own rocky enclosure where he has to play on his own. "It's his new home and he's accepted it," said Klös.
But he still appears twice a day in a larger area where his many fans can see him frolick with Dörflein, the zoo said. Knut has outgrown the room were he spent his first six months being bottle-fed porridge, burped and baby-oiled by Dörflein.
Knut turned six months (more...) last week and has become markedly rougher in his playing with Dörflein, who is often seen wincing with pain when the cub bites him. But Klös said the zoo wasn't worried about Dörflein.
"He's still a little bear and he doesn't pose a threat," said Klös. "And we know his little ways." He said Knut would continue his twice-daily appearances with his various handlers for at least another two months, until the end of the summer season.
The zoo says Dörflein is likely to be safe playing with the fast-growing predator until he's about one year old -- in December this year -- when he will weigh between 60 and 80 kilos. But experts admit they can't be sure and say they will keep reassessing the situation.
Meanwhile, Wirtschaftswoche magazine reported that Knut is likely to boost the zoo's revenues by €5 million by the end of the year. Some 700,000 have piled into the zoo to see the cub since his first public appearance on March 23, and that figure is expected to reach 1 million by the end of the year.
That means the zoo is heading for record total visitor numbers of over 3 million this year, beating the previous record of 2.5 million set in 2006.
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Polar bear cub celebrity Knut has been honing his hunting skills by chasing ducks and squirrels in Berlin Zoo but so far hasn't caught any thanks to the quick intervention of his handlers.
"Some ducks landed in the moat around his enclosure but he couldn't get to them because we got there first," the zoo's bear expert, Heiner Klös, told SPIEGEL ONLINE.
"He's also been showing an interest in squirrels during his morning walks around the zoo." Each day before the zoo opens, Knut goes for a stroll past the cages and enclosures with his keeper Thomas Dörflein, who taught him how to swim last month.
Past strolls have brought him face-to-face -- separated by powerful glass -- with his mother Tosca, who rejected the cub at birth and would probably devour him if she could.
"He has also been interested in the cranes but they were behind a fence," said Klös.
The polar bear cub celebrity, now over 30 kilos (66 pounds), is gradually being weaned off his "mother" Dörflein who hand-reared him, and has been given his own rocky enclosure where he has to play on his own. "It's his new home and he's accepted it," said Klös.
But he still appears twice a day in a larger area where his many fans can see him frolick with Dörflein, the zoo said. Knut has outgrown the room were he spent his first six months being bottle-fed porridge, burped and baby-oiled by Dörflein.
Knut turned six months (more...) last week and has become markedly rougher in his playing with Dörflein, who is often seen wincing with pain when the cub bites him. But Klös said the zoo wasn't worried about Dörflein.
"He's still a little bear and he doesn't pose a threat," said Klös. "And we know his little ways." He said Knut would continue his twice-daily appearances with his various handlers for at least another two months, until the end of the summer season.
The zoo says Dörflein is likely to be safe playing with the fast-growing predator until he's about one year old -- in December this year -- when he will weigh between 60 and 80 kilos. But experts admit they can't be sure and say they will keep reassessing the situation.
Meanwhile, Wirtschaftswoche magazine reported that Knut is likely to boost the zoo's revenues by €5 million by the end of the year. Some 700,000 have piled into the zoo to see the cub since his first public appearance on March 23, and that figure is expected to reach 1 million by the end of the year.
That means the zoo is heading for record total visitor numbers of over 3 million this year, beating the previous record of 2.5 million set in 2006.
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