Orange-crowned warbler, Vermivora celata

A small little bird that spends its days  picking aphids, scale and other small bugs off of bushes and trees. The also hawk insects in air. They commonly live in brushy areas such as our chaparral or coastal sage scrub. They are ground nesters and probably will not survive cats.
Summers in Canada and Alaska, hangs around California all year.

Plant a few Ceanothus and Manzanitas in a clump, put a bird bath somewhere nearby and hope these little birds show up.