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 habitat varies, ranging from bare rock to forests. They typically build their nests under rock crevices or roots, or burrow into soft ground with low growing vegetation. As it frequents the open ocean, little is known about the fork-tailed storm petrel outside of the breeding season. They have been frequently sighted off the Californian coast, making them the most northerly distributed storm petrel during the winter. Sparse sightings also indicate that they forage as far south as Hawaii. Fork-tailed storm petrels are generally silent and only call when entering their breeding colony at night. Their most common call is a