Bears are almost synonymous with strength. They're hulking masses of muscle, with the larger species capable of weighing in at nearly 2,000 pounds. That they manage to be super strong and dangerous while also looking snuggly is one of nature's great ironies.
My lesson on how strong bears really are came from a young female that we'd just received at a past zoo where I worked. She was sent as a future mate for our older resident male, but was still a little on the young side and quite small, so we weren't trying to rush the introduction too quickly. That meant that she was housed alone at the moment, and as such I suspect she was quite bored. I tried to compensate by giving her lots of enrichment.
I hadn't been at that zoo for much longer than she had, and was still figuring a lot of things out, being very new to the bear line. I quickly ran through all of the enrichment that I could think of for her and was worried that I was running out of ideas. One day, I was covering for our big cat keeper when I happened to glance through their enrichment closet. There were plenty of toys in there that I hadn't tried on our young bear, so I decided to try some out. The first one I took was a bowling ball.
I thoroughly cleaned it, removing any trace of cat (to prevent any disease transmission - I wasn't sure how much of a risk it would be, but wanted to be thorough). Then, I drizzled some honey over it, tossed a few raisins and nuts in the finger holes, and placed it in her enclosure.
These are enrichment objects (from another zoo) after lions have finished playing with them. A big polar bear or grizzly bear can weigh more that twice as much as a full-grown lion, so feel free to use your imagination for what those toys can look like.
At first, it worked like a charm. She sniffed it closely, then licked off the honey. She discovered by rolling it around, she could dislodge the raisins and the nuts. Then, once those were eaten, she continued to roll it around still. I was pretty happy with it... until she stood up on her back legs and picked the ball up. Then, to my disbelief, she shuffled a few steps, then threw it forward. Hard. The ball struck a large rock embedded in the floor of the exhibit. A small chip of bowling ball flew off in one direction. A small chip of rock flew off in another. Delighted, she raced ahead and grabbed the ball, the repeated the process. Stand up, pick up, throw. Repeat.
It was at about this minute that I remembered that among the features of the bear habitat was a viewing window. Not a big one - just a small portal - but big enough to allow a bear to climb out of it if it were to, say, be shattered by a bowling ball. She was young, but still a good-sized bear, nearly adult sized. Plus, she was an excellent climber, our zoo was heavily wooded, and we weren't that far from both the perimeter fence and the entry gate. Her being out would definitely be a problem. It seemed only a matter of time before the ball eventually met the window Whether she would think to aim deliberately for the window or whether it might happen by accident was irrelevant. I had to get the ball back.
I spent the next half hour coaxing, begging, pleading, swearing, threatening (to do what I'm not sure), and then pretending to ignore her, all in hopes of getting her into her den so I could get the ball back. Maybe, I thought, I wouldn't have to worry. A few more throws and that ball might break up to be too small for her to damage a window, or even throw effectively. Surely enough, she was whittling it down, chip by chip. Eventually, I did lure her inside, locked her in, then ran out and got the ball.
I made a point of explaining to future keepers that I trained, no bowling balls for bears. The big cat keeper never asked what happened to her bowling ball.