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
Fork-tailed storm petrel finally fledge and leave the burrow. Living in areas with severe climactic conditions, fork-tailed storm petrels have many adaptations to ensure breeding success. Eggs can be left unattended for up to 7 days and still successfully hatch, whereas chick growth rates can be adjusted to being faster or slower depending on food supply, rather at a constant rate like many other birds. The fork-tailed storm petrel is often the sole prey item for a lot of predators early in the breeding season because they return to these remote islands long before any other seabird. These birds consist a significant part