Welcome - again, different states call the bird by different names but the one that comes up more often is the “Gray Jay”.
Here’s good info on it: http://en.wikipedia.org/wiki/Gray_Jay
In terms of size I think this bird is slightly larger than the pne in photot. Also considering that it is the central valley of California where this bird was seen ( hence the altitude is not above 100 ft, the most likely answer would still be the mocking bird. The yards and skies are full of them this time of year, particularly in the central valley of california