Well, I'm no expert on California coyotes, but I assume their breeding habits and roughly the time of year they do so are relatively the same?
Around here they will start to breed just about any time now and the night time serenade of yips and howls have ceased for now. Which means they are either doing it, or getting real close?
Don't ask me why they go silent for a bit during or just before their breeding season, I just know that it happens.
Which also means that right now is prime time for using challenge howls, barks, yips, and bish chirps. Early morning and late evening are best and I have real good luck with the bark..bark..howl, and follow it up with a couple of yips. They think another dog is moving in on their territory and especially the big males are very territorial right now.
Give it a try, you may be surprised to have one come charging in on ya? It sure makes for some exciting hunting action that's for sure!