The lava gull (''Leucophaeus fuliginosus''), also known as the dusky gull, is a medium-sized

gull Gulls, or colloquially seagulls, are seabirds of the subfamily Larinae. They are most closely related to terns and skimmers, distantly related to auks, and even more distantly related to waders. Until the 21st century, most gulls were placed ...

and a member of the "hooded gull" group. It is most closely related to the

Laughing gull The laughing seagull (''Leucophaeus atricilla'') is a medium-sized gull of North America, North and South America. Named for its laugh-like call, it is an opportunistic omnivore and scavenger. It breeds in large colonies mostly along the Atlantic ...

and

Franklin's gull Franklin's gull (''Leucophaeus pipixcan'') is a small (length 12.6–14.2 in, 32–36 cm) gull. The genus name ''Leucophaeus'' is from Ancient Greek ''leukos'', "white", and ''phaios'', "dusky". The specific ''pipixcan'' is a Nahuatl name fo ...

and is the rarest gull in the world. It is endemic to the Galapagos Islands.

Taxonomy and systematics

First described by

John Gould John Gould (; 14 September 1804 – 3 February 1881) was an English ornithologist who published monographs on birds, illustrated by plates produced by his wife, Elizabeth Gould (illustrator), Elizabeth Gould, and several other artists, includ ...

in 1841 from a specimen collected on Santiago Island in the Galápagos. The species is sometimes placed in the genus ''

Larus ''Larus'' is a large genus of gulls with worldwide distribution (by far the greatest species diversity is in the Northern Hemisphere). Many of its species are abundant and well-known birds in their ranges. Until about 2005–2007, most gulls ...

''. It is possibly closely related to the

laughing gull The laughing seagull (''Leucophaeus atricilla'') is a medium-sized gull of North America, North and South America. Named for its laugh-like call, it is an opportunistic omnivore and scavenger. It breeds in large colonies mostly along the Atlantic ...

Description

The lava gull is a distinctive gull, and weighs . The adult

plumage Plumage () is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, there can b ...

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.

Distribution

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.

Behaviour

Breeding

Unlike most gulls which nest close together and sometimes touching, lava gulls are solitary nesters, rarely nesting closer than 100 meters apart. They are highly territorial, defending breeding territories of roughly 2000 sq. meters (70 m diameter) from conspecifics. They nest on the ground, often under the protection of coastal vegetation, and line the nest with plant material. They lay two olive-colored and well-camouflaged eggs that take 32 days to incubate. They generally nest close to calm water, often near lagoons. Breeding appears to be opportunistic and is not restricted to a single season. Young birds fledge at 55 days and continue to be cared for by the adults for several weeks.

Diet and feeding

They are omnivores like most Larus gulls, generally scavenging or stealing from nests and from fishers, but will also catch

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

, small

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s, and newly hatched

lizard Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...

iguana ''Iguana'' (, ) is a genus of herbivorous lizards that are native to tropical areas of Mexico, Central America, South America, and the Caribbean. The genus was first described by Austrian naturalist Josephus Nicolaus Laurenti, J.N. Laurenti in ...

s, and

turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...

s. They also feed on sea lion placenta. On Genovesa they exploit the kleptoparasitic behavior of the

Magnificent frigatebird The magnificent frigatebird (''Fregata magnificens''), frigate petrel or man o' war is a seabird of the frigatebird family Fregatidae. With a length of and wingspan of , it is the largest species of frigatebird. It occurs over tropical and subtr ...

, 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.

Status and conservation

The lava gull is categorized as "vulnerable" by the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...

because it exists in small numbers and though the population is stable, it faces numerous threats.

References

External links

BirdLife Species Factsheet
{{Taxonbar, from=Q596917

lava gull The lava gull (''Leucophaeus fuliginosus''), also known as the dusky gull, is a medium-sized gull and a member of the "hooded gull" group. It is most closely related to the Laughing gull and Franklin's gull and is the rarest gull in the world. It ...

Endemic birds of the Galápagos Islands Galápagos Islands coastal fauna

Taxobox binomials not recognized by IUCN Taxa named by John Gould