|House finch fledgling photo taken Aug. 24, 2014. J.J. Meyer|
That's because many species have multiple nests each season. For example, house finches can nest two or three times each season. Mourning doves are particularly prolific; a pair can produce up to a dozen offspring with up to six broods or hatchings per year.
It's best to hold off on tree trimming until fall. And even then, it's wise to examine trees and bushes carefully for nests before cutting. Hummingbirds start nesting in Southern California in November.
And please keep cats indoors. Cats kill billions of birds each year.