Researchers Use GPS Tracking to Discover How, Where Bears Hibernate
Apparently brown and black bears differ in more than color.
Although native to the same general area in the far northwest region of North America, these species have different preferences for where they bed down for the winter. A black bear will settle in where he pleases (which is just about anywhere, as long as it’s dry), and a brown is a bit more timid and mindful of humans.
These answers were not completely clear until this fall and winter, when scientists from Fish and Game tracked bears in Juneau, Alaska and the Canadian Yukon with GPS tracking devices. Biologists have been studying bears with radio collars for more than 25 years, but now the technology is more exact and sophisticated with GPS tracking, and the devices are much more compact.
Bears are fitted with collars with GPS tracking receivers and modem to transmit location coordinates at regular intervals. With custom-designed software, the researchers can “see” dozens of the napping mammals in real time on the same map. The curious humans then venture out into the field to discover and photograph the wintery homes.
Without GPS tracking, scientists say they wouldn’t be aware of half the bear dens around them.
“Most of the time you could walk right past them and you’d never know a den was there,” said Alaska biologist John Hechtel. “They’re just scattered throughout the landscape under as much as 14 feet of snow.”
Another advantage of the tracking system is scientists can find and document bear hibernation without the need to rustle up the brush in the mountains and forests, risking riling a bear and provoking an attack. Like humans, bears are rather ornery when awakened from deep sleep. Females are particularly dangerous if they are invaded by a human while bedding with their cubs.
What Scientists Discovered with GPS Tracking
Black bears and brown bears both have the same general requirements for making it through the winter: finding cover and staying dry.
Black bears will bed down in just about any environment. GPS tracking showed that they prefer a home with a northern exposure, whether that be a hollowed-out tree or a tangle of tree roots in the hills or under porches or in a shed amid residential neighborhoods. They might lie down in the dirt and let brush and snow cover them, sort of like a beaver den.
Brown bears generally stay away from people. Many of them wait out the winter in rock cavities and under the roots of trees, thousands of feet up in the mountains. Female brown bears tend to pull in vegetation behind them to make a comfy nest.
The GPS tracking program allowed scientists to make a few discoveries about bear hibernating habits.
They discovered that:
·        Dens are not used as year-round homes; only winter getaways.
·        Existing dens are used year after year. So much so that the rocks inside are worn smooth.
·        Bears do not hold exclusive rights to a den. There are only so many natural dens in a territory and an abundance of bears. The best dens seem to go on a first-come, first-served basis. A scientist followed one bear for 8 years with GPS tracking and it over-wintered in the same den only twice.
·        Bears are good housekeepers. They keep their dens very clean. They wake and emerge to “do their business.”
Because the human population is constantly growing and encroaching on open land, scientists feel obligated to protect the native species. GPS tracking is usually the best way to find out how much space a wild animal covers in its natural environment, how it interacts with other animals, how it finds food and what it eats, and what it does at night. Countless species now wear harmless GPS tracking devices, including bears, zebra, seals, deer, birds, elephants and turtles.
GPS tracking systems can either be real-time GPS tracking devices or passive GPS tracking devices. Real-time GPS tracking devices relay location coordinates at regular intervals for “live” monitoring. Passive GPS tracking devices, also known as GPS loggers, record GPS tracking coordinates in memory and the information is downloaded later, once the device is retrieved.
Source: The Juneau Empire
Tags: Bear, Biologists, Black, Brown, GPS Tracking, Hibernate, Radio Collars
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