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

gull Gulls, or colloquially seagulls, are seabirds of the family Laridae in the suborder Lari. They are most closely related to the terns and skimmers and only distantly related to auks, and even more distantly to waders. Until the 21st century ...

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

Laughing gull The laughing gull (''Leucophaeus atricilla'') is a medium-sized gull of 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 coast of North ...

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 f ...

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. He published a number of monographs on birds, illustrated by plates produced by his wife, Elizabeth Gould, and several other artists, including Edward Lear, ...

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 gu ...

''. It is possibly closely related to the

laughing gull The laughing gull (''Leucophaeus atricilla'') is a medium-sized gull of 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 coast of North ...

Description

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

plumage Plumage ( "feather") 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, ...

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. Lava Gull RWD2

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 Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...

, small

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...

s, and newly hatched

lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia altho ...

s, iguanas, and

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

s. 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.

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 the world's most comprehensive inventory of the global conservation status of biolo ...

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 Endemic birds of the Galápagos Islands Galápagos Islands coastal fauna lava gull Taxobox binomials not recognized by IUCN Taxa named by John Gould