Possibly the easiest-to-identify gull in North America, Heermann’s Gulls in breeding plumage are mostly deep storm-cloud gray with a pearly white head and a brilliant red bill. Immatures are also distinctive, with dark sooty brown plumage and little streaking or mottling. These medium-sized gulls breed in Mexico's Gulf of California and then migrate northward to spend late summer and fall along the Pacific Coast. They feed mainly on anchovies and sardines, often harrying pelicans and other seabirds to steal their catches.
Heermann’s Gulls can be scarce outside of Mexico before May, when nonbreeding birds begin to show up on the California coast. From June through September, they are common along the Pacific Coast. Look for them among large flocks of gulls and terns, especially on sandy beaches and in kelp beds just offshore. Because they often pirate fish from Brown Pelicans, watch for pelicans feeding—the gulls are almost certain to be nearby. They remain fairly numerous into December, but by January most will be back on their breeding grounds.
Heermann's Gulls have an unusual "backwards" migration: they breed mostly south of the United States and then move north for the nonbreeding season. After breeding is over in July, the gulls quickly come north all the way to southern Canada. They head back southward by December, and most breeders are at the breeding islands by March.
Perhaps as a result of increasing populations in Mexico, some Heermann's Gulls now breed in California, with the first successful nests at Seaside in central California, where they have nested on artificial islands and rooftops since 1999.
The name of Heermann's Gull refers to Adolphus Lewis Heermann, an American doctor and naturalist who traveled through western North America in the 1850s, as surgeon for the Pacific Railroad Survey expedition.
The Heermann's Gull, like many other gulls, frequently steals food from other birds and often targets Brown Pelicans. An adult Heermann's Gull is most likely to try to steal food from an adult pelican, and an immature gull is more likely to steal from an immature pelican. In the field of animal behavior, the word for stealing is “kleptoparasitism.”
The oldest recorded Heermann's Gull was a female, and at least 24 years old when she was caught and released in Oregon in 2009. She had been banded in Mexico in 1985.
Gulls
