A fresh black bear track on the Canoe Lake #3 to Contact Lake portage on the Kenai Peninsula/Peter Snow photo
Skater Peter Snow never saw the bear on his backcountry adventure among the lakes of the Swanson River canoe route in the Kenai National Wildlife Refuge over the weekend, but he saw its tracks in the fresh snow on one of the portages.
Fat-biker Jim Jager saw his bear late at night last week on an Anchorage bike trail, but thought at first he must be seeing someone’s dog. He expected the bears to be asleep for the winter by the Thanksgiving season in the state’s largest city.
He learned otherwise when the animal stood up on its hind legs to study him.
Both men were left wondering about the relationship of hibernation and weather in the unusual fall of 2018 for coastal Alaska.
Anchorage witnessed an October a staggering 10 degrees above normal. And November is on track to finish 7 to 8 degrees above normal.
Usually it is snowing this time of year on the Kenai and along the northeast rim of the Gulf of Alaska, and it was snowing in the mountains of both areas on Sunday.
But from about 2,000 feet down to sea level, there was generally rain. Early evening temperatures ranged from 37 in the city of Kenai to 35 in Anchorage to 41 in Palmer going south to north up Cook Inlet.
It has been like this for a while now.
Wildlife is responding to the change the way wildlife does. A couple thousand feet high in the Chugach Mountains, moose could be seen over the weekend feeding in willow thickets that would normally be lost or disappearing beneath the snows in normal years.
And some of the bears have clearly decided to postpone their long winter’s nap. Snow said he couldn’t help wonder but “how warming will affect hibernation patterns?”
Be afraid?
With anything and everything potentially related to climate change now under study, it should come as no surprise to learn that scientists have studied that very question.
The conclusion?
“After accounting for individual attributes, we found that the duration
and end of black bear hibernation was most strongly associated
with temperature.” wrote Heather Johnson of Colorado Parks and Recreation and a half-dozen colleagues who spent three years studying hibernating black bears in Colorado. “Indeed, temperature had twice
the magnitude of effect of either natural or human food availability in
decreasing the overall length of hibernation. Our results suggest that
ambient temperature serves as an important trigger of hibernation
behaviour in bears, and corroborates studies on marmots and brown bears that temperature is more influential at driving changes in hibernation than snowpack.”
In many ways their conclusions tracked and documented the observations of biologists monitoring Kodiak brown bears. They decades ago noticed that as long as food is available some of those bears don’t hibernate.
“We found that the start of hibernation was most strongly associated
with individual bear attributes (reproductive status, age and mass), followed by natural food, fall minimum temperatures and development,” Johnson and her team wrote.
The research indicates that in unusually warm falls with adequate food available, more bears will be inclined to delay hibernation. But most of them will generally hibernate on schedule.
So even if some bears are awake later into the fall, your chances of encountering a bear go down as the numbers of bears out and about decrease.
The Colorado study does contains some other interesting observations:
- “Compared to barren females, bears with cubs denned seven days earlier while bears with yearlings denned 13 days later.” (Translation: If you encounter a bear out this late in the season, it highly unlikely to be a sow with cubs of the year, but there is an increased chance it will be a sow with yearlings.)
- “For every year a bear aged, hibernation started approximately 1 day earlier, and for every additional 10 kilograms a bear weighed, hibernation started two days later.” (Translation: The bear most likely to be out this time of year is a younger bear or a well-fed bear. The latter tend to avoid trouble. The former may try to challenge people but can be intimidated.)
- “Both natural food and development delayed hibernation, although
the effect of natural food was stronger. A proportionate 20 percent increase in natural food (based on the observed range of variation) was associated with a 3.8-day delay in hibernation.” (Translation: If you are in an area with late salmon runs or big berry patches still heavily laden despite the cold, you probably will have a better chance of encountering a bear. The study didn’t put a percentage on unnatural foods, ie. human handouts or garbage, but noted bears in populated areas with access to unnatural food sources all hibernate later. If bears are still getting into garbage in your neighborhood, you might want to talk to your neighbors or report them.) - “For each 1°C (1.8 degree F) increase in the average fall minimum temperature, hibernation was postponed 2.3 days.” (Translation: Yeah, warm temperatures can have a significant influence on bear behavior. A 10-degree spike in temperature, according to this calculation, could delay hormal hibernation by almost two weeks.)
Safety issues?
“Given that warmer temperatures and human development both reduced hibernation in our study, we predict that future trajectories of climate and
land use change may increase the length of the active bear season,
with the potential to cause subsequent increases in human–bear
conflicts and bear mortalities,” Johnson and her colleagues wrote.
The residents of Kodiak Island might tell you this problem has already begun.
City officials there revealed at mid-month that if the local brown bears didn’t go to bed soon, they’d be shot.
An extremely late fall and bears habituated to human food are the perfect storm for ursine problems.
The warmth in Kodiak has paralleled that in Anchorage. November is starting to look like the new October there and elsewhere, which might serve as a warning to Alaskans not to put the bear spray away as early as in the past.
But it appeared he might have shot a deer and been carrying it out while attacked. His backpack was never found. His rifle was found on an island ridgetop with bear hair stuck to the electrical tape over the muzzle to keep out snow. A wounded bear was seen in the area.
The vast majority of November through April attacks have involved hunters, trappers or others working in the Alaska wilds in the winter. Herrero and Smith noted that early in the 20th Century nearly half of all bear attacks for any given year involved hunters, but they added that “the percentage of attacks involving hunters has declined while percentage of
those involving outdoor recreationists has increased.”
The numbers likely reflect a national shift in outdoor activities. Two years ago, University of Alaska Southeast professor Forest Wagner was attacked near Haines while skiing in April.
He was leading a mountaineering class of Mount Emmerich when he skied into a grizzly sow with a cub or cubs. Alaska Department of Fish and Game wildlife biologist Stephanie Sell later told Juneau radio station KTOO that Wagner was skiing in an area ideal for bear denning.
Winter is usually considered the “bear safe” season in Alaska because the odds of encountering bears now are very, very low; but there is still that rare possibility.
And given the conditions of the moment, it might be less rare than normal.