Tiny technology tracks small subjects

In effort to monitor growing bear population, DNR uses microchips to tag cubs

April 01, 2006|By CANDUS THOMSON | CANDUS THOMSON,SUN REPORTER

GREEN RIDGE STATE FOREST -- Scarcely bigger than a kitten, the black bear cub tucked away with its slumbering mother was as anonymous as any other woodland creature Tuesday morning.

By lunchtime, the cub had a new identity - microchip 472C4E7628 - as did each of its three siblings, joining supermarket produce, express packages and automobiles in a world where everything is inventoried and coded.

Their mother gave up her anonymity last month. Decked out in a white radio collar, the 238-pound sow broadcasts her position to wildlife biologists who manage the state's 500-plus bears.

Bears, once listed as an endangered species in Maryland, are thriving and moving east as development booms in their longtime habitat in Garrett and western Allegany counties.

Where it used to be rare to see a bear east of U.S. 15 in Frederick County, sightings are more common these days, says Harry Spiker, the leader of the Department of Natural Resources black bear team.

"Eastern Allegany has been on the fringe for the last 20 years or so, and it's now firmly in bear territory," Spiker says. "I would not be surprised to see them move into Carroll and Harford counties. The Baltimore County watershed, the three reservoirs, there's no reason why bears wouldn't settle there. Aberdeen [Proving Ground] is prime bear habitat. It's only a matter of time, and we want to be there when it happens."

The state has responded to the migration by proposing an expansion of the bear hunt this fall, now in its third year, to include eastern Allegany County and the 44,000-acre Green Ridge State Forest.

To get a better count as they plot the bears' eastward progress, biologists are using two new tracking and identifying devices. These cubs are part of a pilot project to see whether tiny microchips embedded in the skin between the shoulder blades can replace the large plastic ear tags used for decades.

Typically, bears are located and tagged in winter months as they hibernate. But while the traditional tags are fine for adult bears, they're too large for tiny ears, meaning the cubs have to be disturbed a second time when they are older.

The microchips are called PIT tags, short for Passive Integrated Transponder. Each one is about the size of a grain of long-grain rice and costs $8. The tags can be read by biologists using hand-held scanners, much the way vets read similar internal ID chips in dogs and cats. A hibernating bear doesn't have to be disturbed to read a tag, putting less stress on both animals and humans.

The sow's radio collar is new, too. Instead of using a 1980s-style tracking collar that emits a signal indicating general location, the $2,000 collars contain a GPS unit that provides biologists with a precise set of coordinates every four hours.

On Tuesday, the mother bear's collar works as advertised.

Stepping from a truck deep in the forest, wildlife technician Georgia Guyton unfurls a four-prong antenna and walks around, consulting a small box in her hand.

Smiling, she looks up. "She's still there," Guyton says, sending biologists scrambling down a steep path embroidered with brambles.

Having already been rousted from her late-winter nap once this season, the mother bear is not an enthusiastic participant. As team members approach her den, she raises up from behind a fallen tree snorts, slaps the wood with her paw and begins a bluff charge.

Spiker fires a small tranquilizer dart into each of her shoulders. Minutes later, the bear is curled on her side, asleep.

"She did everything a good mama bear does to protect her cubs," says Spiker, admiration in his voice.

The sow gets a physical from Dr. Cindy Driscoll, the state veterinarian, and Carol Bradford, a veterinarian intern at the Maryland Zoo in Baltimore. The animal gets a shot of penicillin, a dental check and blood is drawn for analysis later.

As the clock ticks, Spiker frets about the helpless bear overheating and dehydrating in the sun. Humans and coats are used to block the rays, before attention turns to the cubs - three males and a female - being held by bear team members.

The cubs show no fear, clinging to team members with their already developed claws. Their hot, moist breath remains measured as Spiker uses a syringe to slide the chips under the folds of fur at the backs of their necks.

About an hour after she began her nap, the sow gets a smear of Vicks VapoRub on the side of her muzzle to mask human scent and the cubs get a dab of the goo on their heads.

Spiker expects to duplicate the tagging process with as many as 100 bears, using a $2,100 grant from the Maryland Legislative Sportmen's Foundation.

By this time next year, the cubs will have bulked up to 80 to 100 pounds. A full-grown male bear weighs up to 300 pounds and a female as much as 180.

"A sow with four healthy cubs is a good indicator of population growth," says Spiker. "We average 3.1 cubs per sow. That compares to two to three cubs elsewhere, and one to two cubs in the Southwest."

A federal laboratory is analyzing the DNA in hundreds of hair samples gathered last year in areas frequented by the bears to get a more concrete picture of the number and gender of Maryland's bruin population.

"All of these projects are giving us a crystal-clear indication of what we need to do for these animals," says Paul Peditto, head of DNR's Wildlife and Heritage Service. "We've gone from near extinction 53 years ago to a healthy population today. I look at this as a chapter in one of the most successful stories in Maryland's wildlife history."

candy.thomson@baltsun.com

Baltimore Sun Articles
|
|
|
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.