This must be the time for the young'ns recently booted from the nest. I live just south of Griffith Park, Hollywood CA, and spent about 15 minutes starring up into a front yard tree at what would seem to be a juvenile Red-Shouldered from my "Peterson Field Guide. He/she seemed to be dining on a smaller bird as white feathers would occasionaly come floating down.
Also, check out this Osprey video from last year, I think. Quite some meals.