Sorry about your birds. No bears here. In Yosemite from time to time someone leaves a cooler visible in their car....the bears peel open the car doors like we open a sardine can. Would be very difficult to keep a bear out if it really wanted in, construction wise. They're just too powerful. Occasionally someone gets killed by a deer as well, rare, but it does happen. They're not always as docile as you might think. Of course an unthinking human is the cause of these incidents.