Photo: Chris Geirman

By Laura Durenberger-Grunow - Boreal Community Media - April 7, 2023


Spring fever has hit many people living or visiting Cook and Lake County - with many of us looking for some signs of spring. One sign is often black bears emerging from their dens (and the signs they leave that they're around). 

Boreal Community Media talked with Dominique Menard, a naturalist for Sugarloaf Cove Nature Center in Schroeder, Minnesota about black bears, and to find out if our delayed spring has delayed the bears. 

"On average, northern Minnesota black bears typically leave their dens at the end of March or beginning of April," Menard shared. 

Yes, that includes years like 2023, where it's a week into April and most places in our area have over two feet of snow on the ground. 

Menard assured us that "yes, bears are awake, just not as active as they will be soon."

She went on to say that "black bears have a period of "walking hibernation" for about two or three weeks after waking up.  I think of this as the "pre-coffee" stage.  The bear's metabolism is not all the way returned to summer levels, they will be sleeping more hours and not eating or drinking as much."

This "pre-coffee" stage is triggered by a variety of factors such as the overall time of year, location, and temperature. 

Bears in warmer climates have a shorter period of hibernation, while those in northern Minnesota will typically hibernate for five to six months. 

Overall, Mernard mentioned that temperature is usually the main trigger for bears to leave hibernation.

"If there is an unusually warm spring, then bears will wake up earlier regardless of other factors," she added.

For many of us, we think of hibernation as a period of time when organisms simply sleep all winter long. But that's not necessarily always the case. 

Menard expanded on this notion by saying:

"It's also helpful to remember that while we often use "hibernation" as an umbrella term to include many species with reduced activity in winter, there are really many different ways this can happen. 

For example, ground squirrels are "true hibernators."  They go into a state of suspended animation where body temperature drops significantly, and metabolism, heart rate, and breathing all slow.  A state of true hibernation will take a great deal of time and energy to wake from.

Compared to that, chipmunks will undergo a state called torpor, where bodily functions also slow, but generally slightly less extreme than a true hibernation.  Most importantly, torpor takes less energy to 'wake up' from.  The chipmunk will be in this state for several days at a time and then wake up to attend to bodily functions: moving around to warm up, eating stored food, and relieving themselves.  This cycle repeats constantly through the winter."

When it comes to black bears, their hibernation patterns fall more in line with torpor than true hibernation. 

"Bears can stay in this state for months on end. They will exist on stored fat, and are remarkably efficient at "recycling" everything in their body, so they will not need to wake up to relieve themselves. Yet, they will also shift in sleeping positions, and will also wake relatively easily.  So, if something disturbs an individual bear it is very possible for them to wake up even earlier."

This is even true for females when they give birth. 

"It is a myth that the mother is asleep while giving birth- the torpor state means that she can easily wake up and attend to her 1-3 newborn cubs, though some nursing will take place while she is in torpor.

Black bears mate in late May or June, but the egg will not implant and develop until November, and cubs are typically born in the middle of winter in late January, making them quite the outlier for northern mammals!"

That all being said, have there been any confirmed bear sightings in Lake or Cook County yet this year?

Menard shared that she hasn't heard of much bear activity yet, but that those of us in active bear areas (especially Lake Superior) should be ready. 

"If you are in an area where bears are active, now is a good time to bring in feeders," she suggested.

But it's not just bird feeders that can be bear attractants. Trash cans, uncleaned grills, outdoor pet food, and other food-related items can all be tempting for bears. 

"The important thing to keep in mind is that bears will learn food sources and return to them- if you have a bear visit once, they will likely be back.  Keep an eye out for signs of bears such as tracks, scats, or sightings by neighbors and be prepared to switch course and remove feeders for the season if your situation changes," Menard said.