You didn't read my input over a month ago because I'm here in San Diego and I was losing the large buds on my roses everymorning when I would awake I was so sad to see blooms gone. I tried everything but went out th get eight bars of Irish Spring and put them around on the turned over clay pots. Since than I haven't had any destruction but a few bars are missing and this morning I found one with the side chewed and huge teeth marks but the bar was there and the blooms are looking really good. I must say that years ago I had a cottage garden of potted plants and herbs in that same area and over night totally nothing was left. That was a gougher and I found the main hole and dropped in the pellets from Home Depot and flooded it with water till the big gougher came up for air and soon died because they tunnel under the gardens and the lawns eating everything in their path.. Get rid of those huge Roof Rats because they are your biggest enemy because they have powerful teeth and loads of babies that grow very quickly especially if you have compost or leftovers laying around or even the smell of fish emulsion. These guys are always here or in the neighbors gardens which I've warned them for years and so they keep comming back but Rat Bars the Real Kill variety does the thing quickly but you have to hide them from the other pets and children. debbysunshine@hotmail.com

It might be bunnies eating your flowers. I found chicken wire keeps them from getting in out back, and the front they don't bother but they do eat neighbors grass. They must be afraid to the cross the street ;).
For the squirrels...I quit putting in lilies so now they don't come in very often. I flood the ground squirrel tunnels and gophers I trap.
The problem with poisions is that if the animal dies in the open, hawks, coyotes, bobcats etc eat them...then they die also.
Hawks are probably one of the biggest predators on rats and snakes.

Hmmm...South Bay. Any chance that the birds in question might include peafowl? They're not restricted to PV.