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
Ivory gull Ivory gull The ivory gull ("Pagophila eburnea") is a small gull, the only species in the genus Pagophila. It breeds in the high Arctic and has a circumpolar distribution through Greenland, northernmost North America, and Eurasia. The ivory gull was initially described by Constantine Phipps, 2nd Baron Mulgrave in 1774 as "Larus eburneus" from a specimen collected on Spitsbergen. Johann Jakob Kaup later recognized the unique traits of the ivory gull and gave it a monotypic genus, "Pagophila", in 1829. Johan Ernst Gunnerus later gave the species a new specific name, "Pagophila alba". The genus name "Pagophila" is from Ancient