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ENLARGE
Wildlife researcher Dave Immell with the Oregon Department of Fish and Wildlife, hops on a rock to listen to a signal emitting from a bear's radio collar near Copeland Creek.
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ENLARGE
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Jacob Kercher, an assistant wildlife research with ODFW, measures the diameter of a snag tree where a bear has denned for the winter near Copeland Creek recently.
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ENLARGE
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Dave Immell assembles a abstack at the entrance of bear S-010B's den as Jacob Kercher readies the tranquilizer and
sedative in the Black Gorge, near Steamboat Creek last week.
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ENLARGE
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An example of a radio-signal triangulation is penciled on the side of a Steamboat Creek drainage map. Researchers pinpoint radio-collared bears to specific areas by intercepting radio signals and drawing their intersections on a map from the compass bearings that were obtained.
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STEAMBOAT CREEK — Given her druthers, a mother black bear would probably den at the top of a broken tree snag if she knew Dave Immell and Jacob Kercher were coming for her and her cubs.
Fortunately for the Oregon Department of Fish and Wildlife researchers, Oregon black bears prefer a variety of dens for winter hibernation. And radio-collared bears haven't yet made a connection between being easy to find on the ground and the transmitters around their necks.
A week ago Friday, the researchers found themselves deep in a canyon known as the Black Gorge on the east side of Steamboat Creek, staring up at a hollow snag while a radio signal for bear S-010B beeped loudly on their telemeter.
“It’s probably in that tree,” Immell said, losing hope of retrieving the bear’s collar and seeing if she had cubs or yearlings for an ongoing study on the reproductive health of black bears.
The snag stood tall, with claw marks leading from its base to an entrance hole on its side.
But Kercher wasn’t convinced the bear was in it. Every once in a while, a muffled beep came through his headphones that sounded unlike one that would come from the top of a snag.
So he searched for another source.
“You can take the antenna off and just use the coaxial — if you can do that and still pick the signal up, you know you’re close,” Immell said. “You just start circling around that tree and if it’s always pointing back to that tree . . . then for sure it’s in there.”
As Immell spoke, Kercher strode toward a large rock outcropping up the slope.
At its base was the wide opening to a lair — the den of S-010B.
The discovery came after hours of driving ridgetop roads and hiking the canyon in search of her radio signal.
Fortunately for the Oregon Department of Fish and Wildlife researchers, Oregon black bears prefer a variety of dens for winter hibernation. And radio-collared bears haven't yet made a connection between being easy to find on the ground and the transmitters around their necks.
A week ago Friday, the researchers found themselves deep in a canyon known as the Black Gorge on the east side of Steamboat Creek, staring up at a hollow snag while a radio signal for bear S-010B beeped loudly on their telemeter.
“It’s probably in that tree,” Immell said, losing hope of retrieving the bear’s collar and seeing if she had cubs or yearlings for an ongoing study on the reproductive health of black bears.
The snag stood tall, with claw marks leading from its base to an entrance hole on its side.
But Kercher wasn’t convinced the bear was in it. Every once in a while, a muffled beep came through his headphones that sounded unlike one that would come from the top of a snag.
So he searched for another source.
“You can take the antenna off and just use the coaxial — if you can do that and still pick the signal up, you know you’re close,” Immell said. “You just start circling around that tree and if it’s always pointing back to that tree . . . then for sure it’s in there.”
As Immell spoke, Kercher strode toward a large rock outcropping up the slope.
At its base was the wide opening to a lair — the den of S-010B.
The discovery came after hours of driving ridgetop roads and hiking the canyon in search of her radio signal.
<b>DEN INSPECTION</b>
First, Immell had to sedate the bear before he and Kercher could change her collar and survey her cubs.
With deliberate ease, he crawled to the den’s entrance with a jabstick and tranquilizer fixed to the end.
He located a haunch with his flashlight and pushed in the tranquilizer.
About 10 minutes later, Kercher crawled in the den. From its darkness, he handed out, one at a time, two squeaking cubs — a male and a female.
The cubs weighed 4.2 pounds and 4.5 pounds, respectively, and were approximately 45 days old.
Within 15 minutes Kercher had a new collar on the mother.
The “trophy den,” Immell said, had allowed for an easy collar change.
From the entrance to the back wall, the den was about a dozen feet deep. Its width was nearly 10 feet and the ceiling almost 2 feet high — a living room oddity since bears prefer tight spaces.
S-010B was the last bear from a group of 23 for Immell and Kercher to track.
The bears are part of a study that has been ongoing for five years now in the Steamboat Creek area of the Umpqua National Forest and in the Gold Beach area near the Rogue River.
Fourteen of the bears are located near Gold Beach. The remaining nine are around Steamboat Creek.
Immell, an ODFW assistant project leader of wildlife research, has studied bears’ reproductive and survivability rates in Oregon since 1993.
He’s tracked and researched big game out of ODFW’s Roseburg district office since 1996.
When he’s not tracking bears, he tracks elk in the Cascades or nets mule deer from a helicopter over the high desert of Eastern Oregon.
Kercher, a seasonal employee with ODFW since 1999, has tracked bears with Immell for four years and is a trained wildlife biologist.
First, Immell had to sedate the bear before he and Kercher could change her collar and survey her cubs.
With deliberate ease, he crawled to the den’s entrance with a jabstick and tranquilizer fixed to the end.
He located a haunch with his flashlight and pushed in the tranquilizer.
About 10 minutes later, Kercher crawled in the den. From its darkness, he handed out, one at a time, two squeaking cubs — a male and a female.
The cubs weighed 4.2 pounds and 4.5 pounds, respectively, and were approximately 45 days old.
Within 15 minutes Kercher had a new collar on the mother.
The “trophy den,” Immell said, had allowed for an easy collar change.
From the entrance to the back wall, the den was about a dozen feet deep. Its width was nearly 10 feet and the ceiling almost 2 feet high — a living room oddity since bears prefer tight spaces.
S-010B was the last bear from a group of 23 for Immell and Kercher to track.
The bears are part of a study that has been ongoing for five years now in the Steamboat Creek area of the Umpqua National Forest and in the Gold Beach area near the Rogue River.
Fourteen of the bears are located near Gold Beach. The remaining nine are around Steamboat Creek.
Immell, an ODFW assistant project leader of wildlife research, has studied bears’ reproductive and survivability rates in Oregon since 1993.
He’s tracked and researched big game out of ODFW’s Roseburg district office since 1996.
When he’s not tracking bears, he tracks elk in the Cascades or nets mule deer from a helicopter over the high desert of Eastern Oregon.
Kercher, a seasonal employee with ODFW since 1999, has tracked bears with Immell for four years and is a trained wildlife biologist.
Together, for about six weeks each year, they gather age-specific reproductive rates; age at first reproduction; the interbirth interval, or number of years between litters, and mortality and harvest data from bears.
With the data, Immell will build population models and hopes to learn more about the effects of fire suppression, climate change and reduced timber harvest on bears.
Immell said ideally, the study will continue for at least 20 years.
“This is a slow process. We’re trying to get some baseline data,” he said.
In the spring and early summer, Immell and Kercher snare bears for the reproductive study.
Female bears are fixed with radio collars and male bears receive ear tags.
Each radio collar has its own frequency.
At the start of hibernation, around early November, Immell locates each bear’s signal by helicopter so when it comes time to pinpoint them in early February, they are not as difficult to find.
It doesn’t matter if the bears are in huckleberry thickets covered with snow or down steep canyons hammered by rain, Immell and Kercher always find their bear.
However, if a bear is at the top of a snag, it can’t be surveyed. Immell and Kercher recently found six bears in that situation. It remained unknown how many cubs or yearlings they might have had with them.
“That’s kind of the bummer part for us,” Kercher said.
With the data, Immell will build population models and hopes to learn more about the effects of fire suppression, climate change and reduced timber harvest on bears.
Immell said ideally, the study will continue for at least 20 years.
“This is a slow process. We’re trying to get some baseline data,” he said.
In the spring and early summer, Immell and Kercher snare bears for the reproductive study.
Female bears are fixed with radio collars and male bears receive ear tags.
Each radio collar has its own frequency.
At the start of hibernation, around early November, Immell locates each bear’s signal by helicopter so when it comes time to pinpoint them in early February, they are not as difficult to find.
It doesn’t matter if the bears are in huckleberry thickets covered with snow or down steep canyons hammered by rain, Immell and Kercher always find their bear.
However, if a bear is at the top of a snag, it can’t be surveyed. Immell and Kercher recently found six bears in that situation. It remained unknown how many cubs or yearlings they might have had with them.
“That’s kind of the bummer part for us,” Kercher said.
<b>BEARING IN </b>
The process of tracking a bear on foot consists of first intercepting the bear’s radio signal from three different compass bearings.
A signal is strongest when it is directly pointed at with a telemeter.
With detailed forest maps, Immell and Kercher triangulate the signals and pinpoint the bear to a specific area before beginning each hike.
However, Immell and Kercher found bear S-010B’s transmission from only two different areas before beginning their hike in the Black Gorge.
Kercher said the situation is typical when a bear chooses a cave for a den.
“It makes things interesting,” he said.
Bear S-010B had been easier to pinpoint the previous two years because she chose snags for a den. But the wildlife researchers were not able to reach her and gather data on her offspring, much less determine if they were cubs or yearlings.
The bear, Immell said, has been “on the air” for about three years and was due for a collar change since its signal life is about three years.
The process of tracking a bear on foot consists of first intercepting the bear’s radio signal from three different compass bearings.
A signal is strongest when it is directly pointed at with a telemeter.
With detailed forest maps, Immell and Kercher triangulate the signals and pinpoint the bear to a specific area before beginning each hike.
However, Immell and Kercher found bear S-010B’s transmission from only two different areas before beginning their hike in the Black Gorge.
Kercher said the situation is typical when a bear chooses a cave for a den.
“It makes things interesting,” he said.
Bear S-010B had been easier to pinpoint the previous two years because she chose snags for a den. But the wildlife researchers were not able to reach her and gather data on her offspring, much less determine if they were cubs or yearlings.
The bear, Immell said, has been “on the air” for about three years and was due for a collar change since its signal life is about three years.
<b>FUTURE LINEAGE</b>
The survival rate of cubs is about 70 percent.
A litter is usually two or three cubs, with two more common than three.
By age 5, female bears have their first litter and then have litters every other year.
The cubs are born in the den during hibernation. There the mother will stay for approximately six months until May, when the cubs are mobile enough to get around on their own.
Immell said the hibernation period for black bears varies, depending on sex and reproductive status.
A mother with yearlings may den for about four months until late March or April. Solitary females and sub-adult males den for about the same time.
Adult males may den for only three months, or not at all if a constant food source is available.
Oregon black bears prefer log-based dens, with about 60 percent in standing trees.
Dens can be anywhere in a hollow tree, often near the ground, and about 20 percent are in fallen trees. Immell said bears prefer logs’ tight spaces because it helps them preserve energy.
About 20 percent of dens are in caves.
Immell said it will be interesting to see if bear S-010B chooses the same den next winter.
During hibernation, bears do not eat, drink, defecate or urinate — all of the urea is recycled.
“There’s a switch that flips when they hibernate,” Immell said.
Cubs suckle milk while the mother hibernates.
Immell said bears have bones with certain characteristics that are completely different from humans’.
“If we laid around for six months, we’d get osteoporosis. They don’t,” he said.
Because of their physiological oddities, Immell says bears are amazing creatures. He said scientists are studying them more to possibly make breakthroughs in medicine and science.
In the meantime, Immell and his assistant will continue studying black bears on the coast and in the Cascades.
“We’re just trying to balance a bear checkbook,” Immell said.
• You can reach reporter Adam Pearson at 957-4213 or by e-mail at apearson@newsreview.info.
The survival rate of cubs is about 70 percent.
A litter is usually two or three cubs, with two more common than three.
By age 5, female bears have their first litter and then have litters every other year.
The cubs are born in the den during hibernation. There the mother will stay for approximately six months until May, when the cubs are mobile enough to get around on their own.
Immell said the hibernation period for black bears varies, depending on sex and reproductive status.
A mother with yearlings may den for about four months until late March or April. Solitary females and sub-adult males den for about the same time.
Adult males may den for only three months, or not at all if a constant food source is available.
Oregon black bears prefer log-based dens, with about 60 percent in standing trees.
Dens can be anywhere in a hollow tree, often near the ground, and about 20 percent are in fallen trees. Immell said bears prefer logs’ tight spaces because it helps them preserve energy.
About 20 percent of dens are in caves.
Immell said it will be interesting to see if bear S-010B chooses the same den next winter.
During hibernation, bears do not eat, drink, defecate or urinate — all of the urea is recycled.
“There’s a switch that flips when they hibernate,” Immell said.
Cubs suckle milk while the mother hibernates.
Immell said bears have bones with certain characteristics that are completely different from humans’.
“If we laid around for six months, we’d get osteoporosis. They don’t,” he said.
Because of their physiological oddities, Immell says bears are amazing creatures. He said scientists are studying them more to possibly make breakthroughs in medicine and science.
In the meantime, Immell and his assistant will continue studying black bears on the coast and in the Cascades.
“We’re just trying to balance a bear checkbook,” Immell said.
• You can reach reporter Adam Pearson at 957-4213 or by e-mail at apearson@newsreview.info.
