I've seen bats drain feeders overnight! Actually I've seen the bats at the feeders drinking all of the solution. Website http://www.hummingbirds.net/feeders.html states:

Bats
In some parts of the American Southwest near the Mexican border, bats like hummingbird feeders, too. Dan True got this photo of a Mexican long-tongued bat raiding the pantry. These gentle mammals are voracious nectar lovers, but they are also vital pollinators of saguaros, other giant cacti, and the large agaves.

Bats can empty your feeders overnight, every night. If this is a problem for you, use a feeder with bee guards. Taking feeders in overnight will keep the bats away, but remember that hummers start feeding as early as 45 minutes before sunrise, and they really need the energy after a cool night.

Raccoons did the same thing to our feeders a couple times this summer. At least we're pretty sure since there was raccoon hair left behind. Ours are also high above the ground, hanging off a sturdy wrought iron hook on each corner of the deck, so they're pretty brave.

I don't think two stories would be a problem for raccons.
I'm in San Antonio, and we have millions of bats here. I see them at night, but have never had them at my feeders. Actually, I would like to see that. Bats are cool.