I can't help you at all with your question, but, if you would be so kind explain to a east coaster what it is you are talking about??? what is a varmint ramp?  What is this swooping bird/bat thing?  Do you mean that they want the bird/bat to have access to your waterer?  Is the ramp thing there so that varmints can get out of your waterer if they fall in?  I know you are speaking English, but, I still have no idea what you are saying :) 

If you don't want to take the time to explain, no problem.  It is interesting to see/hear how things are so different in this big country :)