What is a bear garden?

In Mary Poppins a “bear garden” is mentioned. What is that?

Okay, so that is just about the worse thing ever produced by humans. Damn Mary Poppins, you really bring it!

Normally I would go out of my way to quote a wiki article, but honestly the first-hand accounts of animal cruelty are too much for me to commit to talkgroup. Go and read it. Don’t let humans repeat it.