Lava Gull

The lava gull is a distinctive gull, 51 to 55 cm (20–22 in) and weighs 380 g (13 oz). The adult plumage consists of a sooty brown to black head, which unlike other dark hooded gulls doesn't vary by season. The wings are dark gray with a contrasting white line on the leading edge, thought to play a function in displays and camouflage. Its dark gray body contrasts with a paler gray belly. The uppertail is white and grey lower down. The bill and legs are black, and the inside of the mouth is scarlet. It has white upper and lower eyebrows, with red lids. Immature gulls are generally dark brown.

The entire population lives on the Galapagos Islands where it is found predominantly on the islands of Santa Cruz, Isabela, San Cristobal and Genovesa. Previously its population was estimated at 300–400 pairs; this estimate was revised downwards to 300-600 individuals in 2015. It is currently considered the rarest gull in the world.

They are omnivores like most Larus gulls, generally scavenging or stealing from nests and from fishers, but will also catch fish, small crustaceans, and newly hatched lizards, iguanas, and turtles. They also feed on sea lion placenta. On Genovesa they exploit the kleptoparasitic behavior of the Magnificent frigatebird, capitalizing on the botched attempts by these frigatebirds to steal fish from various nesting seabirds. Potential nest predators include owls, frigatebirds and other lava gulls, as well as introduced mammals.