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 visible. The distinguishing feature of fork-tailed storm petrels is their overall bluish-gray plumage. They generally have a paler underside, which contrasts the darker colours under its wing. They also have a dark gray forehead, a black ear patch, and a small black bill. Other storm petrels are significantly darker, such as the similar looking Ashy storm petrel.. However, fork-tailed storm petrels from southern populations are somewhat darker than those in the north. Males and females of this species are generally very similar in colour and size. Juveniles also resemble adults with the exception of having a less noticeable notch in