Friday, January 30, 2009

Effects of past climate changes

Climate change wiped out cave bears 13 millennia earlier than thought.

Enormous cave bears, Ursus spelaeus, that once inhabited a large swathe of Europe, from Spain to the Urals, died out 27,800 years ago, around 13 millennia earlier than was previously believed, scientists have reported.

The new date coincides with a period of significant climate change, known as the Last Glacial Maximum, when a marked cooling in temperature resulted in the reduction or loss of vegetation forming the main component of the cave bears' diet.

In a study published in Boreas, researchers suggest it was this deterioration in food supply that led to the extinction of the cave bear, one of a group of 'megafauna' - including woolly mammoth, woolly rhinoceros, giant deer and cave lion - to disappear during the last Ice Age.

They found no convincing evidence of human involvement in the disappearance of these bears. The team used both new data and existing records of radiocarbon dating on cave bear remains to construct their chronology for cave bear extinction.

"Our work shows that the cave bear, among the megafauna that became extinct during the Last Glacial period in Europe, was one of the earliest to disappear," said Dr Martina Pacher of the Department of Palaeontology at the University of Vienna. "Other, later extinctions happened at different times within the last 15,000 years."

Dr Pacher carried out the research alongside Professor Anthony J. Stuart of the Natural History Museum, London, and the University of Durham.

Many scientists previously claimed that cave bears survived until at least 15,000 years ago, but Dr Pacher and Professor Stuart claim that the methodology of these earlier studies included many errors in dating as well as confusion between cave bear and brown bear remains.

The pair also concluded, from evidence on skull anatomy, bone collagen and teeth, that these extinct mammals were predominantly vegetarian, eating a specialised diet of high-quality plants. Compared with other megafaunal species that would also become extinct, the cave bear had a relatively restricted geographical range, being confined to Europe, which may offer an explanation as to why it died out so much earlier than the rest.

"Its highly specialised mode of life, especially a diet of high-quality plants, and its restricted distribution left it vulnerable to extinction as the climate cooled and its food source diminished," said Dr Pacher.

The brown bear, with which Ursus spelaeus shares a common ancestor, was spread throughout Europe and much of northern Asia and has survived to the present day.

"A fundamental question to be answered by future research is: why did the brown bear survive to the present day, while the cave bear did not?" said Professor Stuart. Answers to this question may involve different dietary preferences, hibernation strategies, geographical ranges, habitat preferences and perhaps predation by humans.

Cave bears were heavily built animals, with males growing up to around 1000kg. The maximum recorded weight of both Kodiak bears and polar bears - the largest bears living today - is 800kg, with averages of around 500kg.

Scientists have recovered a large quantity of cave bear remains from many cave sites, where they are believed to have died during winter hibernation. Caves provide an ideal environment for the preservation of these remains.

Despite over 200 years of scientific study - beginning in 1794 when a young anatomist, J. Rosenmüller, first described bones from the Zoolithenhöhle in Bavaria as belonging to a new extinct species, which he called cave bear - the timing and cause of its extinction remain controversial.

By far the best source of information on the appearance of cave bears in the flesh is to be found in red pigment cave paintings in the Grotte Chauvet in the Ardèche region of southern France. These are the only depictions in Palaeolithic art that can be attributed unambiguously to the cave bear.

source SCIENCE, 13 OCTOBER 2006

Wednesday, January 14, 2009

Bear Vocalizations: What Do They Mean?

Being a zoo keeper I get asked a lot of questions about the animals I work with and one question that comes up a lot is: what type of vocalizations do animals make and what do they mean?

Bears have several types of vocalizations. Some species vocalize more than others. Knowing what these sounds mean can help us understand bear behavior and help with their care.

Photo of brown bear yearlings play-fighting and vocalizing in Alaska. photo credit: Chris Morgan.

Giant pandas have some unique vocalizations. They bleat which is a friendly greeting, honk when anxious or distressed and during the breeding season a receptive female will chirp when meeting a male. Sloth bears make a huffing sound when sucking up food, which sounds like a vacuum.

Most bear species make vocalizations that sound like a huff, chomp, woof, growl, and/or bark which mean the bear is agitated, angry or annoyed. A bawl, bellow, squeal or whimper indicates pain. A mumble, hum, or purr indicates contentment.

In many cases vocalizations are done along with some type of body posturing. These are visual clues as to how the bear is feeling. Depending on how the bear is standing, holding its head, the ear placement and how they move can tell a lot about what the bear is thinking and whether it is a dominant or subordinate animal. Bears would rather avoid a fight so using vocalizations and posturing can help eliminate serious conflicts and injuries and along with this, conserve energy they need to survive.

Vocalizations can be heard on the North American Bear Center’s website.

Wendy Gardner, GBOP team

Monday, January 05, 2009

Village Books in Bellingham welcomes...

Join us on Wednesday, January 7th at 7pm as The Grizzly Bear Outreach Project and Village Books are proud to welcome to Bellingham David Knibb, author of Grizzly Wars: The Public Fight over the Great Bear.

Long a magnificent symbol of the wild, grizzly bears are perhaps the most controversial species in North America. In Grizzly Wars, David Knibb explores policy and political issues involved in managing and attempting to save the grizzly bear, highlighting the critical role of state governments in the recovery process, the importance of providing linked habitat areas, and our need to cooperate with Canada in managing grizzlies who inhabit border areas.

David Knibb has a background in environmental law, forestry, and wildlife management. An activist on resource conservation and environment issues in the Mountain West for nearly 45 years, he is also author of Backyard Wilderness, a chronicle of the Congressional battle over the Alpine Lakes Wilderness in Washington’s Cascades.

Chris Morgan, Director of the acclaimed Grizzly Bear Outreach Project will be at the event to share information about grizzly bears in the North Cascades. Swing by to pick up a free poster and learn about grizzlies (we may have as few as 10 of them in the Cascades!).