By Misi Stine, Environmental Educator and member of the MN Herpetological Society
American_black_bear_(Ursus_americanus)_-_Jasper_National_Park_01 Thomas Fuhrmann, CC BY-SA 4.0
When you make a list of large mammals found in Minnesota, black bears (Ursus americanus) are right at the top. Black bears in Minnesota are 5- 6 feet long and weigh from 150-500 pounds, the heavier end of the scale favoring males. Although they are called black bears, their coloring can range from black to dark and light brown, with less than 10% of the brown color phase documented in Minnesota.
Historically, Minnesota was also home to grizzly bears (Ursus arctos horribilis) and there is evidence of them living almost as far east as Ely, 5,000-8,000 years ago, when more of Minnesota was prairie habitat. By the 1800’s the prairie had moved to the far western part of the state and so did the grizzly population. As European Settlers found their way to this area, they converted most of Minnesota’s prairie to agricultural land and had little interest in co-existing with animals like bears. By the early 1900’s there were no more grizzly bears that called Minnesota home. However, black bears were able to persist and have been able to maintain a sustainable population to the present day.
Fortress_of_the_Bear_two_black_bears_2022_2 Rob Bixby, CC BY 2.0
The black bear population, which has fluctuated over time, is currently estimated to be between 13,000-18,000 animals. As mentioned in a previous article (Would You Poke a Sleeping Bear?) they hibernate through Minnesota winters, going up to six or seven months without eating, drinking, or going to the bathroom, but lose very little muscle mass or strength. As a longtime volunteer at the Wildlife Science Center in Stacy, I had the opportunity to observe researchers who are interested in learning more about how bears are able to maintain muscle mass and strength, despite long periods of inactivity. The researchers were looking at whether the mechanism that protects muscle mass and strength in bears could be applied in humans, who after a short period of inactivity, lose strength and experience muscle atrophy, which can take months of rehabilitation to overcome.
Black bear mating season is May-July but the egg does not implant until November when the females enter hibernation. But if the mother does not have enough fat stores to sustain the pregnancy and care for the cubs, the egg can be reabsorbed and not result in a pregnancy. Milk for the cubs, takes a lot of her fat stores but will help them survive the early part of their life. Cubs will stay with mom until they are approximately 1 year and 17 months of age, being required to disperse and become independent just in time for mating season. The survival rate of cubs is about 80%, which is higher compared to other large mammals. Wolves for example have survival rates that average 40-60%.
Upon waking up in the spring, bears forage for vegetation, and as the season progresses, they eat ants and ant pupae, a variety of seasonal berries, and then switch to tree nuts in the fall, with a liking for acorns and hazelnuts. At their peak, bears foraging for up to 20 hours a day and will travel long distances searching for food, especially in the fall. They can move 100-150 miles in some cases to put on enough fat for a long winters rest. Although they will typically return to their home range, where they spend most of their summer, to den.
Minnesota bears have traditionally been found in forests and other areas of dense cover in the northern part of the state. But in recent years there have been a few reports of bears showing up unexpected areas south and east of their traditional home range. The MNDNR has asked that citizens report bear sightings through their website: dnr.state.mn.us/hunting/bear/bear-sightings.html
Black_bear_(53285215621) USFWS Midwest Region from Midwest Region, United States, Public domain.
The average life span of a black bear can be 21-39 ½ years old. Until 17 months of age, the primary cause of mortality is accidental causes (falling from trees, etc.), starvation, and predation. Interestingly, very few bears die from parasites and diseases. Although there was a report in October of 2022 of a black bear cub dying from Highly Pathogenic Avian Influenza (HPAI) in Glacier Bay National Park. Nearly all adult bears die from human related causes, most are killed by being hunted, and some are killed by cars. The average age that a bear is taken by a hunter in Minnesota is 2 years old for males, and 3 years old for females.
The question I have been pondering is how to discuss managing woodlands for bears, while recognizing the potential issues. In general, managing woodlands for different age classes of oak trees and hazelnuts, as well as incorporating native shrubs and trees that produce berry crops will help support bears in a woodland habitat.
But perhaps more important is managing your human occupied space. Here are the top tips for avoiding conflicts with bears:
Cinnamon_Bear_Cub_Garbage_22 Gillfoto, CC BY-SA 4.0
Never feed or approach bears, a fed bear is a dead bear, as they say.
Secure food sources, garbage, and recycling so that you don’t reward bears and reinforce the idea that human occupied areas provide them with things they need to survive.
Remove bird feeders during the times of the years when bears are active.
Never store pet food or livestock feeds outside.
Clean and store your grills and smokers in a locked shed or garage.
Stay in communication with your neighbors about bear activity in the area.
For more tips on being bear aware when hiking, camping, and what to do if you have an encounter with bear click here: https://bearwise.org/
Finally, there was a great webinar from Minnesota DNR Bear Biologist, Andrew Tri, on April 3, 2024, called No Country for Old Bears (Episode 159), the recording can be found here: dnr.state.mn.us/fishwildlife/outreach/webinar-archive.html The webinar shares information on a long term study of bear mortality and other fascinating information about one of the large mammals that calls Minnesota home.
Bear Facts: Do grizzlies live in Minnesota. (n.d.). Retrieved from North American Bear Center: https://bear.org/bear-facts/do-grizzlies-live-in-minnesota/
Bear Facts: Longevity and causes of death. (n.d.). Retrieved from North American Bear Center: https://bear.org/bear-facts/longevity-and-causes-of-death/
Bear Management. (n.d.). Retrieved from Minnesota Department of Natural Resources: https://www.dnr.state.mn.us/bear/index.html
Bear Safety Tips. (n.d.). Retrieved from Bearwise: https://bearwise.org/bear-safety-tips/bear-encounter/
Bears: Bear Status Trends. (n.d.). Retrieved from North American Bear Center: https://bear.org/fact-category/black-bears/
Black Bears. (n.d.). Retrieved from Minnesota Department of Natural Resources: https://www.dnr.state.mn.us/mammals/blackbear.html
Preserve, G. B. (n.d.). Black Bear Cub Avian Influenza 2022. Retrieved from National Park Service: https://www.nps.gov/articles/000/black-bear-cub-avian-influenza-2022.htm
Report a Bear Sighting. (n.d.). Retrieved from Minnesota Department of Natural Resources: https://www.dnr.state.mn.us/hunting/bear/bear-sightings.html
Safety Around Bears. (n.d.). Retrieved from National Park Service: https://www.nps.gov/subjects/bears/safety.htm#:~:text=Bear%20attacks%20are%20rare%3B%20most,have%20the%20most%20effective%20reaction.
Tri, A. (2022). Status of Minnesota Black Bears 2022. St Paul, Minnesota: Minnesota Department of Natural Resources.