California gulls are everywhere. They're at the beach, in the parking lots, they've very adaptable to human environments.
This is an adult California gull. Note the white spots on the tips of his primaries.
They have yellow beaks with a red spot.
This guy was at the Golden Gate Park. He was very aggressive about asking people for food. There was a woman napping on the grass and he walked all around her to see if he could steal some food.
This is a juvenile California gull. He's still wearing a first winter coat. Their bellies get increasingly white as they age.
He looked really nice against the waves.
Here's a bottom view of another juvenile.