I believe these both show relatively fresh plumage, and so are both juveniles rather than one being an adult female; http://www.pbase.com/image/136634815, taken around the same time, is probably another angle on the paler one on the right. The two were in a family group of four, including the adult male http://www.pbase.com/image/135994787 , that frequented Palo Alto Baylands in June 2011.