Red-legged Cormorant
Encyclopedia
The Red-legged Cormorant, Phalacrocorax gaimardi, also known as the Red-legged Shag, Red-footed Cormorant, Red-footed Shag, Gaimard’s Cormorant and Grey Cormorant, is a resident of the coastline of South America
. It is non-colonial unlike most seabirds. The Red-legged Cormorant has not been observed wing-spreading, which is characteristic of most cormorant
species. It is considered near threatened under the IUCN Red List of Threatened Species.
. Its 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.
, with a long neck, streamlined body, webbed feet and a long, thin hooked bill. Its body length is 71–76 cm (28–29.9 ), with an average wingspan of 91 cm (35.8 in). It weighs 1.3–1.5 kg (2.9–3.3 ). There is no sexual dimorphism
between the male and female Red-legged Cormorants.
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 coloration.
Juvenile Red-legged Cormorants usually possess paler, brown plumage with a speckling of white around the throat. Juvenile plumage coloration 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.
. 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
.
Red-legged Cormorants nest sparsely on steep rock faces, including coastal cliffs, rocky islet
s, 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.
s, but hunting in pairs or small flocks may occur. Most Red-legged Cormorants forage
no further then 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 8–10 m (26.2–32.8 ) below the surface in pursuit of prey. Its diet mainly consists of fish
, specifically including eel
s and anchovies
, and planktonic crustacean
s.
, 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 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
, 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.
.
along with humans, who consume adults, nestlings and eggs. Golden Eagle
s also take adults. 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.
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. It is non-colonial unlike most seabirds. The Red-legged Cormorant has not been observed wing-spreading, which is characteristic of most cormorant
Cormorant
The bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...
species. It is considered near threatened under the IUCN Red List of Threatened Species.
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 Spotted ShagSpotted Shag
The Spotted Shag or Parekareka, Phalacrocorax punctatus, is a species of cormorant endemic to New Zealand. Originally classified as Phalacrocorax punctatus, it is sufficiently different in appearance from typical members of that genus that to be for a time placed in a separate genus, Stictocarbo,...
. Its 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.
Description
The Red-legged Cormorant is a medium sized seabirdSeabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
, with a long neck, streamlined body, webbed feet and a long, thin hooked bill. Its body length is 71–76 cm (28–29.9 ), with an average wingspan of 91 cm (35.8 in). It weighs 1.3–1.5 kg (2.9–3.3 ). There is no sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
between the male and female Red-legged Cormorants.
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
Gular skin
Gular skin , in ornithology, is an area of featherless skin on birds that joins the lower mandible of the beak to the bird's neck....
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 coloration.
Juvenile Red-legged Cormorants usually possess paler, brown plumage with a speckling of white around the throat. Juvenile plumage coloration 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 AmericaSouth America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. On the Pacific coast it ranges from Macabi Island, Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
to Chiloe Island
Chiloé Island
Chiloé Island , also known as Greater Island of Chiloé , is the largest island of the Chiloé Archipelago off the coast of Chile, in the Pacific Ocean...
, Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
. There are small isolated populations on the Atlantic coast scattered across Santa Cruz, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. It rarely occurs further south than the Strait of Magellan
Strait of Magellan
The Strait of Magellan comprises a navigable sea route immediately south of mainland South America and north of Tierra del Fuego...
.
Red-legged Cormorants nest sparsely on steep rock faces, including coastal cliffs, rocky islet
Islet
An islet is a very small island.- Types :As suggested by its origin as islette, an Old French diminutive of "isle", use of the term implies small size, but little attention is given to drawing an upper limit on its applicability....
s, 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
Forage
Forage is plant material eaten by grazing livestock.Historically the term forage has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used more loosely to include similar plants cut for fodder and carried to the animals, especially...
within inshore bodies of water and in shallow offshore waters.
Feeding
Red-legged Cormorants are generally solitary foragerForager
A forager is one who forages, i.e. looks for forage.Forager may refer to:*A hunter-gatherer*Forager , a fictional superhero published by DC Comics*Foraging theory, a branch of behavioral ecology...
s, but hunting in pairs or small flocks may occur. Most Red-legged Cormorants forage
Forage
Forage is plant material eaten by grazing livestock.Historically the term forage has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used more loosely to include similar plants cut for fodder and carried to the animals, especially...
no further then 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 8–10 m (26.2–32.8 ) below the surface in pursuit of prey. Its diet mainly consists of fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, specifically including eel
Eel
Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...
s and anchovies
Anchovy
Anchovies are a family of small, common salt-water forage fish. There are 144 species in 17 genera, found in the Atlantic, Indian, and Pacific Oceans. Anchovies are usually classified as an oily fish.-Description:...
, and planktonic crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s.
Reproduction
The Red-legged Cormorant is a non-colonial seabirdSeabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
, instead living in pairs or small groups. Courtship
Courtship
Courtship is the period in a couple's relationship which precedes their engagement and marriage, or establishment of an agreed relationship of a more enduring kind. In courtship, a couple get to know each other and decide if there will be an engagement or other such agreement...
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 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
Guano is the excrement of seabirds, cave dwelling bats, and seals. Guano manure is an effective fertilizer due to its high levels of phosphorus and nitrogen and also its lack of odor. It was an important source of nitrates for gunpowder...
, 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
Altricial
Altricial, meaning "requiring nourishment", refers to a pattern of growth and development in organisms which are incapable of moving around on their own soon after hatching or being born...
, incubation period averages 30 days and the chick-rearing period is 60-70 days.
Vocalizations
The Red-legged Cormorants vocalizations are unlike most seabirds, they consist of high-pitched chirps and chirrups more like a songbirdSongbird
A songbird is a bird belonging to the suborder Passeri of the perching birds . Another name that is sometimes seen as scientific or vernacular name is Oscines, from Latin oscen, "a songbird"...
.
Predation
Due to the Red-legged Cormorants habit of nesting on cliffs with sheer rock faces and no ground approach, they are inaccessible to most predators. Their main predators is the Kelp GullKelp Gull
The Kelp Gull , also known as the Dominican Gull, breeds on coasts and islands through much of the southern hemisphere. The race L. d. vetula occurs around southern Africa, and nominate L. d...
along with humans, who consume adults, nestlings and eggs. Golden Eagle
Golden Eagle
The Golden Eagle is one of the best known birds of prey in the Northern Hemisphere. Like all eagles, it belongs to the family Accipitridae. Once widespread across the Holarctic, it has disappeared from many of the more heavily populated areas...
s also take adults. 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.