Heermann’s Gull

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 percent nest on the island of Isla Rasa, Mexico; smaller colonies range as far north as California. Post breeding dispersal occurs commonly to central California, and less commonly north as far as British Columbia and south as far as Guatemala.

Current threats to this gull include the effects of weather on prey species, but Isla Rasa was declared a sanctuary in 1964, and egg-collecting and disturbance during the breeding season is discouraged.