Hello toadlover, thank you for sharing the story with us! What part of NorCal do you live in may I ask? Chances are, you have western toads (Anaxyrus boreas) in your backyard. Unfortunately, these toads tend to breed in lakes and slow-moving parts of rivers so they may not breed in your yard. But the water source you set up will probably attract Pacific chorus frog to breed in around next March! Tadpoles and toadlets of western toads are fed upon by some birds, garter snake, and some predatory insects. But once adulthood is reached, all those warts (glands) produces nasty secretion which repels most predators. I don't know if this species exhibits sexual dimorphism, but a mature male should have nuptial pad on thumbs of forearms and are capable of calling.