Heermann's Gull is a Western specialty, occurring only along the North American Pacific coast, spending most of its time offshore. They breed only on islands in the Gulf of California which they share with (and kleptoparasitize) Elegant Terns, following them North in the late Summer and early Fall. This gull is attractive to look at, but is a nasty customer, being jaeger like in its flight and aggressiveness, attacking and forcing terns, other gulls, and even pelicans to drop their prey for them to grab. It is a four-year gull, acquiring its breeding plumage in its fourth year after hatching. The adults shown below are preparing to move to the breeding grounds, and are showing some pre-breeding activities. Long calls can have several functions, but are used most frequently on the breeding grounds - the one shown (unfortunately only from the back) is the first I have seen here. The all dark subadult individual shown below resembles the winter adult, and will have its first breeding plumage next year.