A six-year survey establishes a baseline bear population density in Game Management Unit 1D which extends from Sullivan Island, to Skagway, and out to the Canadian border.
State bear biologist Anthony Crupi presented the results of the survey during a library meeting on June 7. Speaking to a standing-room-only crowd, he explained how the bears were collared and tagged using a helicopter or foot snares.
It’s a laborious process. Fish and Game did a similar study of Malaspina bears near Yakutat in 2015, and they captured hair samples in barbed wires wrapped around trees, hair snares, or corralling bears through barbed wire areas using scent lures. So, in the summer of 2021, Crupi and his team divided the Upper Lynn Canal game unit area into roughly 5 sq. mi grids and spent nearly 2.5 months installing cameras and walking over 450 miles to collect 1,267 black and brown bear hair samples.
In the end Crupi said it took him a year to analyze five pounds of bear hair.
“They take the hair and cut the follicle off. The follicle is put through [DNA tests],” Crupi said.
The team found that 307 brown bears populate the area – give or take a few.
“[There’s] a confidence interval of 258 to 365,” Crupi said. “So 95% of the time, this estimate is going to fall within that range, which is a range that we can manage.”
But it wasn’t just the number of bears they were studying, Crupi and his team also looked at their habits — where they like to den. It turns out bears are very selective in the types of terrain and snow characteristics that they use for denning.
In some places, Crupi said they use cave dens.
“In the study areas, like in Yakutat, we would see some bears a third of the population denned at low elevation, a third of the population denned between 500 and 1000 feet. And then a third of the population denned at really high elevations,” he said. “Here we’re seeing that most bears are denning over 1000 feet elevation.”
This type of denning location data is important – particularly for people who spent a lot of time outside in the winter. In February 2021, three snowboarders inadvertently disturbed a bear den at 1,600 feet elevation near Chilkoot Lake. One of them was mauled, badly.
“Bears don’t want to be disturbed in the winter,” Crupi said. “They don’t have the resources and fat reserves to survive once awakened. Most of the dens that we find here are excavated into the earth. So they climb up to about a 35 degree slope, they burrow straight in, and then they make a chamber that’s in there and they raise their cubs … nursing them in the spring as they come out. The females with cubs of the year will spend several weeks to a month up at those higher elevations.”
One other big focus of Crupi’s research is management to avoid having more sows killed. In the summer of 2020, 49 bears were killed in what was widely dubbed Bearpocalypse. At least 24 of the dead bears were females.
Fish and Game staff are concerned that because females don’t reproduce quickly – they start when they’re about 5-years-old — it will take longer to replenish the local bear population. Looking at the data, if a sow has two cubs, according to Crupi, one is more likely to die in the first year. After the cubs are weaned, they are more likely to die.
“And maybe over the course of her lifetime, if she lived all the way through, she maybe has about four cubs that are going to survive. So it’s important to look at that female component, because it means so much to the future population,” Crupi said.