OK. I'm pretty much just going to put a hole in a one gallon bucket so my pigeons can put their heads through and drink , but can't bathe or poop in the water. I don't know how big to make to hole though. I don't want it so big that they can get IN it, but I want them to be able to put their heads through easily. I have West of Englands and Birmingham rollers if that makes a difference on the size it need to be.