Hello, and thanks for your question and your patience. I see that you posted last night.
I think your first step should be to find out where they are breeding (water source) and try to block their access to your property with a fence or other structure (between your backyard and the water source) that will deter them from entering. Also, treating your property for insects would be advantageous, since these frogs subsist on eating insects. If you remove their food, they will seek other accomodations.
As a last resort, you can contact someone from your city's Animal Control and/or Wildlife department, and ask them to remove the frogs from your property, then release them in a safe area for protected species.
I wish you much good luck in resolving this problem!
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Edited by Cher on 5/24/2010 at 6:56 PM EST