Swallow-tailed gull and hunting over the open oceans, and migrating eastward to the coasts of Ecuador and Peru. The swallow-tailed gull is unique among the gulls in feeding exclusively nocturnally, mostly on fish and squid which rise to the surface at night to feed on plankton. It leaves the colony as a flock at dusk, with a great deal of screaming and display. Calls and displays are quite different from other gulls, most resembling the vocalisations of the black-legged kittiwake and Sabine's gull. The loudest and most commonly heard call is an alarm referred to as "rattle-and-whistle", a gurgling scream made with
Swallow-tailed gull the head moving side to side. This call is contagious, with other birds joining in without seeing the cause. A loud and rapid "kweek, kweek, kweek" is the greeting call between mates, made with the head and neck curved forward to the ground. The swallow-tailed gull breeds from about 5 years old, with pairs frequently staying together from year to year. Most breed throughout the year in mixed colonies on the cliffs of the Galápagos Islands sometimes on flat areas, and food for the young is hunted from the seas near to the nesting colonies. The nest is made on