The swallow-tailed gull (*Creagrus furcatus*) is a unique equatorial seabird belonging to the gull family, Laridae. As the only species in the genus *Creagrus*, which derives its name from Latin and Greek words meaning "butcher," this name is thought to refer to its hooked bill, reminiscent of a butcher's hook. The primary breeding grounds for this species are the rocky shores and cliffs of the Galapagos Islands, particularly on Hood, Tower, and Wolf Islands, with smaller populations on other islands. Swallow-tailed gulls are more commonly found on the eastern islands, where the waters are warmer. Notably, the swallow-tailed gull is the only nocturnal gull in the world, primarily foraging for squid at night, though it also hunts small fish. Its eyes are adapted for night vision, featuring a larger size compared to other gulls and a unique tissue layer that reflects light back through the retina, enhancing its sensitivity to low light conditions. The global population of swallow-tailed gulls is estimated at around 35,000 individuals, with most breeding occurring in the Galapagos. A small number also breed on Malpelo Island in Colombia. When not breeding, adults can be found along the Pacific coast of South America, ranging from Ecuador to Chile. Breeding adults exhibit grey plumage with a distinctive black head, red eye-ring, pink legs, and a dark bill featuring a pale tip and a white spot at the base. Non-breeding adults have a white head adorned with a thick black eye-ring, while juveniles resemble non-breeding adults but have a duskier appearance and an entirely dark bill. Swallow-tailed gulls breed asynchronously, lacking a defined breeding season, resulting in nests being found year-round. While they may form loose colonies, they prefer to keep considerable distances between nests. Males are responsible for building nests, which are typically located on steep, rocky slopes, cliffs, stony beaches just above the wave line, or under vegetation. Nests are primarily composed of stones and lava fragments. Each female lays a single egg, and both parents share incubation duties. The egg hatches after approximately 35 days, and both parents feed the chick for up to three months. After the breeding season, adults may leave the Galapagos for four to five months, foraging in the open seas.