The Alaska Department of Fish and Game is four years into a five year study of the Brown Bear population of the upper Lynn Canal, in this case known as management unit 1D, which extends from the Endicott river in the south to Skagway in the north, and the Katzehin valley in the east to the the Canadian border in the west. Anthony Crupi, Wildlife Research Biologist with the department, was in Haines this weekend to track bear movements and tend to the game cameras he uses to gather data.
“One of the major goals of this project is to look at the population demographics, so what are bears reproduction rates and survival and mortality.”
He uses various methods for understanding what the bears are doing.
“The primary way that we have been collecting data for the last few years is to mark a sample of the population with radio collars, and ear tags so that they retain their marks, and from that we were able to get a good idea on where bears were traveling.”
The collars are a thick belt with a battery pack, a GPS, radio transmitter and temperature sensor. They release automatically at a set date, one or two years after being placed on the bear.
“It’s very interesting to learn about the location of bears because we are able to identify some of the key habitats and the resources that are important for bears.”
To place a collar on a bear, the researchers first approach them, on foot or by helicopter. Sometimes the bears are snared. The crew then uses tranquilizer darts,
“And then we have about an hour process, taking measurements on the bear, we find out their age, we weigh them, we measure their total length, their girth, their skull size, from a lot of these things we are able to look at the bear’s health and condition.”
Another method they use to learn about the population is to place barbed wire at strategic locations, with the hope that passing bears will brush against it and hair will get tangled in the barbs. Last year five pounds of hair were collected this way. They then run a DNA analysis on the hair.
“We caught 1250 samples of hair, so depending on where we caught a bear one time , and then recaptured them another time, we have about 900 samples of Brown and Black bears collected across a 600 square mile area.”
All this allows Crupi to see individual bear’s movements. Some movements are impressive. One bear swam across the canal from the Katzehin. Or this one:
“I think of one three year old female that we had captured near Mount Riley, and she denned over near Rainbow Glacier, and just in the month of May went all the way from town to Glacier Bay, to north of Haines Junction, and then Down the Tahini, and all the way back down to Glacier point, so in just the month of May, she had traveled 250 miles.”
At this time of year though, traveling isn’t on a bear’s mind.
“The snow is starting to come down. Bears are starting to finish up their hyperphagia where they are really trying to accumulate as much fat as possible, so that they can survive the dormancy period, which can last five to six months. Yesterday you could hear bears all across the places where you see eagles right now, so bears are trying to put on the last few pounds of fat before they head up to the den to hibernate.”
Crupi hopes to have a population size estimate by the end of winter.