They'll gnaw their way through anything plastic! We used to put out a goldfinch feeder like this:
We also had to replace it several times a year because of the squirrels.
Now we get the Droll Yankees
brand goldfinch feeder because they offer a lifetime guarantee - and stand by it. Sadly, they don't make the upside-down feeder.
We used to keep our seed buckets (5-gallon covered tubs) in the garage. This past winter I moved them to the basement, figuring as long as we didn't have snow it would be easier to go up the bulkhead steps and fill the feeders right outside the basement. Now that it's summer, I thought of putting them IN the bulkhead. However, there have been too many bear sightings in eastern MA. I'm afraid a BEAR might smell it that way and rip the bulkhead open.
Don't want to test my theory that the doors are probably bear-proof.