
Nombre en español: Gaviota Gris
Nombre en inglés: Gray Gull
Nombre científico: Leucophaeus modestus
Familia: Laridae
Categorías: Errática
La gaviota garuma o gaviota gris (Leucophaeus modestus, antes Larus modestus) es una especie de ave Charadriiforme de la familia Laridae autóctona de Sudamérica, aunque solo cría en el desierto de Atacama.

Descripción
Es una gaviota sin dimorfismo sexual, Cabeza blanca en verano; y gris pardusca en invierno, cuerpo gris y más oscuro en partes superiores. primarias negruzcas; secundarias negruzcas con punta blanca formando una línea terminal. cola gris con banda subterminal negruzca. patas negras y pico negro. Se alimenta principalmente de emerita analoga conocida como limache o pulgón de mar.
Anteriormente incluida en el género Larus. Esta especie se reproduce en desiertos de interior en Perú y Chile y fuera de época reproductiva se le encuentra en el suroccidente de Colombia. Su nombre Leucophaeus hace referencia a la coloración de su cuerpo y deriva de las raíces griegas leukos = blanco y phaios = oscuro. El epíteto modestus deriva del latín y significa simple o plano.
Tamaño y forma
Mide cerca de 45 cm y pesa de 360 a 400 g. Presenta pico y patas negruzcas e iris café. Su cuerpo es principalmente gris opaco con la frente blanca y las rémiges negruzcas con amplia banda blanca en el borde posterior de las plumas secundarias. Su cola es gris con una banda subterminal negra y ápice blanco. En plumaje no reproductivo su cabeza es totalmente café grisácea. Los inmaduros son más parduscos por debajo y sin blanco en la cabeza. Los jóvenes son de color café opaco uniforme con las alas y la cola negruzcas con márgenes ante.
Especies similares
El adulto se reconoce fácilmente gracias a combinación de plumaje gris opaco con o sin frente blanca. Los inmaduros se confunden fácilmente con otras gaviotas inmaduras pero ésta generalmente es más gris con la rabadilla y cola oscuras.
Distribución
Esta especie se encuentra a lo largo de la costa de Suramérica desde el norte de Chile hasta el sur de Colombia y ocasionalmente Panamá. En Colombia ha sido registrada en la costa del departamento de Nariño en el municipio de Tumaco y la isla Gorgona.

Habitat
Utiliza playas arenosas y en la época de reproducción se le encuentra en desiertos áridos del norte Chile y sur de Perú.
Alimentación
El cangrejo Emerita análoga constituye un recurso muy importante en su dieta. También se alimenta de peces, poliquetos y desechos de barcos pesqueros.
Reproducción
Su época reproductiva abarca los meses desde noviembre hasta enero. Anida en desiertos de Perú y Chile. Su nido es una excavación redondeada en el suelo generalmente al lado de una piedra. Ponen de 1 a 3 huevos (usualmente 2) de color blanco o levemente grisáceo a salmón pálido, los cuales incuban ambos padres durante 29 a 32 días. Uno de los padres atiende el nido durante el día mientras el otro busca alimento en la costa. Las crías vuelan hacia la costa cerca del día 40 después de la eclosión.

Comportamiento
Con frecuencia se le observa en playas arenosas alimentándose de cangrejos que quedan expuestos al retroceder las olas. También captura peces mediante zambullidas poco profundas y en ocasiones sigue barcos pesqueros. Todos sus despliegues conductuales durante la época reproductiva y la cópula los efectúan en la costa pero la postura la realizan decenas de km al interior del continente. En los años en los que el fenómeno del niño es muy severo esta especie no se reproduce.

Grey gull
The grey gull, also known as garuma gull (Leucophaeus modestus) is a medium-sized gull native to South America. Unusual among gulls, it breeds inland in the extremely dry Atacama Desert in northern Chile, although it is present as a non-breeding bird along much of the Pacific coast of South America.
Description
The sexes are similar in grey gulls. Adults grow to a length of about 45 cm (18 in) and weigh some 360 to 400 g (13 to 14 oz). The head is white in summer but brownish-grey in winter. The body and wings are grey with the dorsal surface rather darker than the ventral region. The flight feathers are black and the inner primaries and the secondaries have white tips, visible in flight. The tail has a band of black with a white trailing edge. The legs and beak are black and the iris is brown. The call is similar to that of the laughing gull (Leucophaeus atricilla).
Distribution
The grey gull breeds inland in the Atacama Desert in northern Chile. Its non-breeding range includes Costa Rica, Colombia, Ecuador, Peru and Chile, and it has been recorded in the Falkland Islands, South Georgia and the South Sandwich Islands. It is a vagrant to Panama.
Behaviour
Breeding
For many years, it was a mystery as to where this bird breeds because no coastal colonies had been identified. However, in the 1970s, it was discovered that it bred in the Atacama Desert in the interior of Chile. This hot and arid environment has few predators and may be relatively safe for the breeding gulls. The site chosen for the nest, a scrape in the sand and often near rocks, is a waterless region some 35 to 100 km (22 to 62 mi) from the coast.[4] Once the eggs hatch, the parents take it in turn to make the round trip to the sea to bring food and water to their offspring.
The humidity, wind speed, air and surface temperatures vary widely on a daily basis and the gull has to use various thermo-regulatory mechanisms when nesting to maintain its body temperature and that of its eggs and chicks within acceptable limits. In the hottest part of the day the parent bird stands over its nest to prevent the eggs or chicks overheating. Its chief predator is the turkey vulture (Cathartes aura) and when threatened, the incubating parent sometimes leaves the nest temporarily, and when this happens the eggs need to have impervious shells in order to avoid losing too much water through evaporation. In fact, the evaporative loss from the eggs is found to be about one third of that which occurs in Heermann’s gull (Larus heermanni), another desert nesting species.
Feeding
The typical habitat of the grey gull is sandy beaches and mudflats along the western coasts of South America where it probes with its beak in the sediment for invertebrate prey, particularly mole crabs. It also eats fish and ragworms, scavenges for offal and sometimes follows fishing boats.
Status
The grey gull has a restricted inland breeding range and a limited wintering range along the coasts of Ecuador, Peru and Chile. The population trend is believed to be downwards. However, the total number of birds is sufficiently large to justify listing the grey gull as being of «least concern» rather than including it in a more threatened category.
The Gray Gull is one of the most common species on the Pacific Coast influenced by the Humboldt Current. For years it was a mystery as to where this species bred. They were seen copulating on the coast, vocalizing and displaying, but no nests were found. Given the many thousands present on shore it was a paradox that no colonies had been discovered. It was not until the early 1970s that it was confirmed that this gull breeds deep in the absolute desert of northern Chile. It takes flat areas in the desert, where often no measurable rainfall exists in a year, a decade, or more. Lacking the basic element of life, water, these breeding areas are surprisingly safe as there are few to no predators there. As the gulls are highly mobile they can commute from the inland colonies to the sea daily and provide food to the chicks. It is thought that the gray plumage coloration is an adaptation to life in hot, sunny places, as melanin keeps feathers from becoming faded and weakened by light, and that they may be able to use the dark plumage to radiate heat more efficiently than translucent white plumage. Most other desert nesting gulls, even if unrelated, are gray. The Gray Gull is vocally quite similar to the Laughing Gull (Leucophaeus atricilla) and is likely closely related to it.

Fuentes: Wikipedia/eBird/xeno-canto/WikiAves/Neotropical Birds