Leucophaeus modestus (Tschudi, 1843)

Nomenclature

This species, commonly known as the grey gull, has the scientific name Leucophaeus modestus (Tschudi, 1843).

Sexual Dimorphism

Male and female grey gulls have similar appearance.

Size and Weight

Adult grey gulls reach an approximate length of 45 cm (18 in), with a weight ranging from 360 to 400 g (13 to 14 oz).

Seasonal Head Coloration

During the summer, adult grey gulls have white heads, while their heads become brownish-grey in winter.

Body and Wing Plumage

Their body and wings are grey, with the dorsal surface being noticeably darker than the ventral region.

Flight Feather Characteristics

Their flight feathers are black, and the inner primaries and secondaries have white tips that are visible when the bird is in flight.

Tail Plumage

The tail features a black band with a white trailing edge.

Soft Part Coloration

The legs and beak are black, and the iris is brown.

Vocalization

The grey gull's call is similar to that of the laughing gull, Leucophaeus atricilla.

Breeding Range

The grey gull breeds inland in the Atacama Desert of northern Chile.

Non-breeding Range

During the non-breeding season, its range covers Costa Rica, Colombia, Ecuador, Peru, and Chile.

Additional Recorded Range

It has also been recorded in the Falkland Islands, South Georgia, and the South Sandwich Islands.

Vagrant Occurrences

It occurs as a vagrant in Panama and Florida.

Unconfirmed Range Record

A 1987 earlier report of the species in Louisiana has not been accepted by a birdwatching authority.