Generally, when do black bears start hibernating?

And what environmental and/or instinctual factors play a part? Is it based on an temperature over a period of time? Snowfall? Sun angle?

Mike

I'm no bear biologist, but I have had bears visiting our bird feeders in November and returning as early as April.

Let’s hope it’s on Monday Night Football. Skol Vikings.

They will den up when food becomes scarce. The bears have been out feeding on acorns and corn recently in the Detroit Lakes area.

KarlK: "They will den up when food becomes scarce. The bears have been out feeding on acorns and corn recently in the Detroit Lakes area."

+1 on dwindling food plus short days and cold/snow. Females first, males follow. Big snow covers the remaining food and moves them to den faster. For northern Wisconsin, it seems like now, late Nov, to mid-December is pretty typical.

I've seen bear prints from them stealing beaver meat, out of the marten traps, in Northern Quetico, in late November.
My trapping friend (Bud), said... "be careful, he's big, and still hungry"

Once upon a time I did bear research. There is no one answer to this. Some bears hibernate in September, others will stay active into December. I think pregnant sows will den earlier, and subadult males will tend to be active later but I'm not sure if that is a hard rule...I witnessed that in my study. Also, some bears sleep very soundly so that you can walk right up to them and poke them with a syringe full of tranquilizer, and others will not let you approach within 100 feet. There's a wide variety of dens too, everything from burrows to open nests. Some bears also make these mysterious 100 mile migrations to den, only to return to their home ranges in the spring.

My dog hasn’t pointed a hibernating bear yet this hunting season. Usually by December he’s already pointed at a few.

There's still been a fair amount of bear activity in and around Duluth. I suspect after this weekend though there wont be much.

I believe the SNF & Voyageurs - Black Bear contract for 2023-24 calls for a December 15th (11:59pm) through April 14th (11:59pm) dormancy period. It used to run from Dec 1 - April 15, but in 2017 the northern bears demanded a shorter mandated hibernation, citing the Smoky Mtn NP/Black Bear contractual agreement which was significantly shorter. I don't get it - - if I could sleep more, I would!

HowardSprague: "I believe the SNF & Voyageurs - Black Bear contract for 2023-24 calls for a December 15th (11:59pm) through April 14th (11:59pm) dormancy period. It used to run from Dec 1 - April 15, but in 2017 the northern bears demanded a shorter mandated hibernation, citing the Smoky Mtn NP/Black Bear contractual agreement which was significantly shorter. I don't get it - - if I could sleep more, I would!
"

I wouldn't expect anything else but such a well researched and comprehensive answer from you, Howie. It makes perfect sense.

Ha!!

Mike

Be alert to the possibility that that sleep might be interrupted in a warm winter with early melting into dens.

February 17, 1981, along the Kekekabic Trail on a trip about to be aborted because of ice conditions:

Last year Nov. 19th. Get a warm day they come out some, especially in deer hunting country to lunch on Gut piles.

HowardSprague: "I believe the SNF & Voyageurs - Black Bear contract for 2023-24 calls for a December 15th (11:59pm) through April 14th (11:59pm) dormancy period. It used to run from Dec 1 - April 15, but in 2017 the northern bears demanded a shorter mandated hibernation, citing the Smoky Mtn NP/Black Bear contractual agreement which was significantly shorter. I don't get it - - if I could sleep more, I would!
"

Love it !

Here is what The American Black Bear Center has to say about hibernation:

Bear Hibernation

After putting the Vikings to bed.