a black bear can kill a man (or a dog) with a single swat of its paw.
I suppose anything is possible. But is it realistic? Has it ever happened?
Googling 'man killed by single punch' finds several instance where a person killed a person with one punch. I also find a lion killed a person with a single swipe. But not finding anything about a black bear doing this.
Are there any records of this happening?
I am going to say yes, it is possible mostly because humans kill other humans with a single punch from time to time and black bears are certainly stronger.
Cupido said there are “hundreds” of documented one-punch deaths nationwide.
One-punch deaths fall even further down the list. But it happens often enough that Gunson, without pause, is able to describe precisely how a sock to the face can end a life.
“They fall over backwards and they hit the back of their head,” Gunson said. “They often end up having a skull fracture.”
However, I can find no record of it happening in Wikipedias list of fatal bear attacks in North America. From the research that I did for this answer, it seems that most bear attacks are a lot messier than a single punch kill.
On the other hand people have survived punching bears.
A Canadian man had to punch a black bear in the nose to force it outside after it followed a toddler into a British Columbia family's home.
Nelson tried to swing at the bear but missed, hitting it in the teeth. The bear hit back, scratching Nelson across the chest and face.
"I knew it would swing first with its left but it would really come with its right, because most bears are right-handed," Nelson said.
So Nelson swung a second time.
'Most bears are right-handed.'
"I had the perfect shot to take. I did an underhand and hit it right in the snout."
Depends on the size of the bear.
Black bears vary in size, small female bears can weigh in under 100 lbs, which makes them about the same size as a large dog. But big black bears can weigh in at more than 600 lbs. The largest black bear on record was in New Brunswick in Canada, and is estimated to have weighed ~1,100 lbs!
A swat to the head by a bear of sufficient mass will undoubtedly be enough to end your life, as sure as a baseball bat to the head can kill you. Keep in mind that a seemingly innocuous hit to the head can be fatal to humans.
The strike force of a bear should not be underestimated. Grizzly bears for example have allegedly been recorded on multiple occasions—although occurrences are still very rare—decapitating moose with one swipe to the head (moose have since been discovered to have a peculiar weakness in their necks that make them prone to decapitation, but still). A large Black Bear is about the same size as an average Grizzly, so it's not unreasonable to assume a big enough black bear could potentially take your head off if it landed a well placed swat your cranium, although you'd more than likely be sent flying with your head still attached.
