The Heermann's Gull (Larus heermanni) is a gull resident in the United States and Mexico. Of the current population of about 150,000 pairs, 90% nest on the island of Isla Rasa off Baja California in the Gulf of California, with smaller colonies as far north as California and as far south as Nayarit. After breeding, birds commonly disperse to central California, and less commonly north as far as British Columbia and south as far as Guatemala....
