So being resistent to curious and hungry mice and rats is pretty important. Birds are dirty enough by themselves, but add some vermin and you will definitely hear from the neighbors. 

My attempt at this was to have the peanuts drop into a funnel before being dispensed. The idea is that if a mouse (or tiny rat) manages to crawl up the dispense chute, they won't be able to reach the peanuts. Granted, they could possibly get into the enclosure and cause problems for the feeder, but they will do it on an empty stomach.

Mice would be more of a problem than rats as most rats would be a little too big to get all the way into the enclosure though the dispense opening.

It's been outside for over a week now in an area where I haven't had a day go by without seeing at least one rat - even in the daytime. No issues yet. I'm not at ground level and it's a newish building, so that helps.