Bear teeth help scientists monitor NC black bear populations

dblustein@newsobserver.comAugust 6, 2013 

  • The bear facts

    • North Carolina has two distinct black bear populations: one on the coast, the other in the mountains.

    • The world’s largest black bear on record was harvested in Craven County in 1998. It weighed 880 pounds.

    • Coastal bears get large because of longer growing seasons and abundant agriculture. They’ve been known to feed on wheat, corn and soybean crops.

    • The oldest bear harvested in 2012 was nearly 18 years old. The Carteret County female weighed 278 pounds.

Whenever a black bear is killed in North Carolina, whether by a car or a hunter, Colleen Olfenbuttel wants a small part of the animal: the two tiny teeth just behind the upper canines.

It turns out that counting growth rings in those teeth is the best way to determine a bear’s age – information that helps scientists such as Olfenbuttel at the N.C. Wildlife Resources Commission assess the health of the state’s growing bear population and decide how to manage it.

For more than 35 years, the state’s Black Bear Cooperator Program has collected thousands of the bear teeth, the majority from hunters. The teeth have no known function and can even be removed from live – but hopefully tranquilized – bears.

Many bear hunters are happy to send in their teeth. Olfenbuttel’s team gets teeth from 40 to 50 percent of the black bears killed each year.

By participating in the program, hunters help out the scientists and get information about the ages of their bears. But those aren’t the only incentives.

“They’ll actually send you a hat,” said Jim Noles, 58, a Greensboro bear hunter and the president of the N.C. Bear Hunters Association.

The blaze orange hat features a new black bear logo each year, and it’s quite popular with hunters. Some have been known to wear it year-round.

“An unexpected part of my job is sometimes I’m a fashion designer,” said Olfenbuttel, 39.

Analyzing the teeth

Olfenbuttel sends the teeth gathered from North Carolina bears to Gary Matson, 72, a scientist in Montana.

Matson’s lab processes 400 teeth per day – about 90,000 per year – sent in from around the world. He first softens the teeth with acid and then embeds them in wax so that he can make fine slices using a microtome, a sophisticated version of a deli meat slicer. The thin slices are observed under a microscope, and the growth rings are counted.

“Nobody understands why the annual rings are formed,” Matson said. But a dark layer corresponds to each winter of the bear’s life.

The distribution of ages of the bears represents the health of the population, Matson said.

Olfenbuttel uses this age information to monitor and manage black bear populations in North Carolina. In July, she received the results from Matson’s lab of the tooth age analysis of 1,442 North Carolina bears harvested in 2012. In the coming weeks, she’ll be using a computer model to analyze the data and come up with an updated bear population estimate.

Black bear comeback

A rapid decline in North Carolina’s bear population began in the late 1800s, largely because of the clearing of forests, loss of bear food from chestnut blight and unregulated killing.

During his first hunting season at age 11 back in 1966, Noles only saw one bear track.

“There just weren’t any bears,” he said.

But the black bear has made a remarkable comeback in the state, with 6 percent average annual population growth over the past decade.

“We have restored bears to North Carolina,” Olfenbuttel said.

There were an estimated 17,912 bears in North Carolina in 2011, up from fewer than 5,000 in 1980.

Noles attributes the comeback to bear sanctuaries, which set aside hundreds of thousands of acres of protected land for one of the state’s largest mammals starting in the early 1970s. Hunting regulations also have helped the black bear bounce back.

Olfenbuttel’s challenge is to stabilize the state’s bear population. A recent increase in damage to agricultural crops by bears is a concern.

“Hunting plays a key role in helping to manage bear populations,” she said.

Up next: GPS devices

During the nonconsecutive weeks of a hunting season that runs from October to December, Olfenbuttel’s office operates roving check stations where hunters can weigh their bears and pass off teeth.

Next year, her team will put GPS tracking devices on black bears in the Asheville area to monitor their movements.

In the past decade, more bears have been spotted near populated areas, partly due to expanding development. They usually stick around because of attractive odors such as those from garbage, uncleaned grills and bird feeders.

Suburban bears

Bear research to date has been mostly restricted to remote areas, Olfenbuttel said. The Asheville tracking project will expand what biologists know about how bears move through cities and towns.

“We can’t keep bears out of suburban and urban areas,” Olfenbuttel said.

Olfenbuttel’s continued quest to learn more about bears will benefit from legislation enacted in July that requires hunters to purchase a bear management stamp starting next year.

With the new program, Olfenbuttel will be able to track the people hunting bears in the state and better promote tooth collection efforts. She hopes to collect more teeth, which will mean more information to guide hunting and conservation regulations aimed at maintaining stable black bear populations.

Blustein: 919-829-4627

News & Observer is pleased to provide this opportunity to share information, experiences and observations about what's in the news. Some of the comments may be reprinted elsewhere in the site or in the newspaper. We encourage lively, open debate on the issues of the day, and ask that you refrain from profanity, hate speech, personal comments and remarks that are off point. Thank you for taking the time to offer your thoughts.

Commenting FAQs | Terms of Service