Did the California seagulls come from California?

The California gull (Larus californicus) is not actually from California.

It is native to the western coasts of North America from Alaska to Baja California, Mexico, and inhabits the coastlines and inland waterways of several states in the western US, including California, Oregon, Washington, and Idaho, as well as British Columbia, Canada.

So while California is part of its natural range, it didn't originate specifically from California.