The red-legged cormorant (''Poikilocarbo gaimardi''), also known as the red-legged shag, red-footed cormorant, red-footed shag, Gaimard's cormorant and grey cormorant,Nelson, J. B. 2005. Cormorants and shags. Pages 512–14. In C. M. Perrins, W. J. Bock and J. Kikkawa, eds. Pelicans, Cormorants, and their Relatives. Oxford University Press, New York. is a species of

cormorant Phalacrocoracidae is a family of approximately 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed, but in 2021 the IOC adopted a consensus taxonomy of seven ge ...

resident to the coastline of South America. It is the only member of the genus ''Poikilocarbo.'' It is non-colonial unlike most seabirds. The red-legged cormorant has not been observed wing-spreading, which is unusual among

species.Johnsgard, P. A. 1993. Cormorants and shags (Phalacrocoracidae). Pages 311–314 In A. Matthew, ed. Cormorants, Darters and Pelicans of the World. Smithsonian Institution Press, Washington.

Taxonomy

The red-legged cormorant is placed within the genus ''Phalacrocorax'', but it has been debated that it should be placed within ''Notocarbo'' as phylogenetic studies suggest that it is most closely related to other southern-hemisphere shags, such as the spotted shag.del Hoya, J., Elliot, A. and Sargatal, J. 1992. Family Phalacrocoracidae (cormorants) species accounts. Pages 351–352. In R. Mascort, ed. Handbook of the Birds of the World Volume I Ostrich to Ducks. Lynx Edicions, Barcelona. A 2014 study found it to represent the second most

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

genus of cormorant, with only '' Microcarbo'' being more basal, and thus reclassified into the genus ''Poikilocarbo''. This classification was followed by the IOC in 2021. It has been suggested that the population of red-legged cormorants on the Atlantic coast are a separate subspecies. They are slightly smaller and have marginally paler plumage compared to the birds of the Pacific coast. ''Poikilocarbo'' is thought to have diverged from the rest of the Phalacrocoracidae between 12.0 - 13.5 million years ago.

Description

The red-legged cormorant is a medium-sized seabird, with a long neck, streamlined body, webbed feet and a long, thin hooked bill. Its body length is , with an average wingspan of . It weighs . There is no sexual dimorphism between the male and female birds.Red-legged cormorant (''Phalacrocorax gaimardi''). ARKive. http://www.arkive.org/red-legged-cormorant/phalacrocorax-gaimardi/#text=Glossary . October 14th, 2011. The red-legged cormorant's appearance is unmistakable. Breeding adults have a smoky grey body, with a slightly paler underside. They have scattered areas of white filoplumes behind the eyes and down the neck. The wing coverts have a speckled, silvery grey appearance, followed by broad black wing tips. The tail is also black. The eyes are green, surrounded by sixteen tiny blue marks. The bill is yellow, shading to orange toward the base, the gular skin is a vibrant orange or red. The legs and feet are a striking coral red. Non-breeding adults look similar to breeding adults. They lack the white filoplumes, the wing coverts appear less silvery, but more dark grey, and the bill and gular skin are duller in colouration. Juvenile red-legged cormorants usually possess paler, brown plumage with a speckling of white around the throat. Juvenile plumage colouration can be highly variable between the Atlantic and Pacific coasts. Their eyes are grey and their bills and gular skin range from black to orange. The legs and feet can be a dull orange to a reddish black.

Distribution and habitat

The red-legged cormorant is native to the coast of South America. On the Pacific coast it ranges from Macabi Island, Peru to Chiloe Island, Chile. There are small isolated populations on the Atlantic coast scattered across Santa Cruz, Argentina. It rarely occurs further south than the

Strait of Magellan The Strait of Magellan (), also called the Straits of Magellan, is a navigable sea route in southern Chile separating mainland South America to the north and Tierra del Fuego to the south. The strait is considered the most important natural pass ...

.Harrison, P. 1983. Family Phalacrocoracidae cormorants, shags. Pages 122 and 304. In Seabirds, An Identification Guide. Houghton Mifflin Company, Boston. Red-legged cormorants nest sparsely on steep rock faces, including coastal cliffs, rocky islets, and sea caverns. They become virtually undetectable against these rocky outcrops by their speckled grey plumage, with the exception of their colourful bills and feet. They forage within inshore bodies of water and in shallow offshore waters.

Behaviour

Breeding

The red-legged cormorant is a non-colonial seabird, instead living in pairs or small groups. Courtship typically occurs in January and February. The males can engage in elaborate mating displays, which include darting and throwback postures. During darting, males chirp quietly while moving the head back and forth exposing the interior of the mouth. When the female advances, the male displays a throwback posture; outstretching the neck and pointing the bill towards the tail. The female may respond to the male's display by hopping and throat clicking. When the female selects a male, periods of allopreening ensue, followed by copulation. Red-legged cormorant pairs are observed to be

monogamous Monogamy ( ) is a form of Dyad (sociology), dyadic Intimate relationship, relationship in which an individual has only one Significant other, partner during their lifetime. Alternately, only one partner at any one time (Monogamy#Serial monogamy, ...

for at least one season. Nests are constructed on steep cliffs and are usually isolated from other birds, but can form small colonies on rare occasions. They are composed of feathers,

guano Guano (Spanish from qu, wanu) is the accumulated excrement of seabirds or bats. As a manure, guano is a highly effective fertilizer due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. G ...

, seaweed, the cases of tube-dwelling worms and even garbage. They have been observed diving 8 to 10 meters collecting billfulls of various nesting materials. Egg laying takes place between October and January, with clutch sizes averaging three eggs. After hatching, the nestlings initially have no feathers, but are quickly covered in brownish down. As with all cormorants, nestlings are altricial, incubation period averages 30 days and the chick-rearing period is 60–70 days.

Feeding

Red-legged cormorants are generally solitary foragers, but hunting in pairs or small flocks may occur. Most red-legged cormorants forage no further than 3 km away from their nest. They hunt in inshore waters, including estuaries, and in shallow offshore waters. They never enter exclusively fresh water. Many red-legged cormorants forage at low tide, presumably to minimize their travel time to and from the surface and to maximize time searching for food. They can dive below the surface in pursuit of prey. Their diet mainly consists of fish, specifically including eels and anchovies, and

planktonic Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

crustaceans.

Voice

The red-legged cormorants calls are unlike most seabirds; they consist of high-pitched chirps and chirrups more like a songbird.

Status and conservation

The cormorant is considered to be Near Threatened on the

IUCN Red List of Threatened Species 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 biologi ...

Predation

Due to the birds' habit of nesting on cliffs with sheer rock faces and no ground approach, they are inaccessible to most predators. Their main predators are kelp gulls, as well as humans, who consume adults, nestlings and eggs. The red-legged cormorant's threat display appears to be underdeveloped, consisting only of gaping and thrusting the bill towards the intruder. This could be due to its solitary life and lack of predators.