Fr: Cormoran de Magellan
Ang: Rock Shag – Magellanic Cormorant
All: Felsenscharbe
Esp: Cormorán Magallánico
Ita: Cormorano di Magellano
Nd: Magelhaenaalscholver
Sd: Magellanskarv
Port: Biguá-das-rochas


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Rock Shag or Magellanic Cormorant
Phalacrocorax magellanicus

Suliformes Order – Phalacrocoracidae Family

The Rock Shag is a monotypic South American species. It is also known as Magellanic Cormorant, related to its range in the austral New World. This is an elegant bird with black-and-white plumage, often seen perched on rocks, giving it one of the four English names, Rock Shag.
This species also breeds in the Falklands.

Length: 66-71 cm
Wingspan: 92 cm

The adult has black upperparts with purplish-blue to greenish gloss, including head, neck, back, rump, uppertail-coverts and thighs.
The underparts are white, but the underwing including wing-coverts and flight feathers, is blackish. The tail is dull black.

On the head, we can see a white patch on the rear of the ear-coverts. This patch varies seasonally and is sometimes absent.
There is sometimes a small white area on the anterior throat that can be more extended, forming a large white patch on the foreneck in non-breeding plumage.  
The bare skin of the face is bright red, extending from lores and around the eyes, down to the gape and the base of the lower mandible. It is mostly orange around the eyes.
The bill is dark grey to blackish. The eyes are red to deep chestnut. Legs and webbed feet are pink when brightest. The rear of the tarsi and the soles are dark grey.

The breeding adult shows long, scattered white filoplumes on head, neck, back, rump and secondary upperwing-coverts. They may form conspicuous white tufts on crown-sides, just above the ear-covert patch. These white filoplumes are denser on the thighs.

In non-breeding condition, the face is duller, especially on lores and gape. Legs and feet are duller too and the red iris turns deep chestnut. The foreneck shows a white area from the lower throat.

Both sexes are similar, with the male slightly larger than the female.
The juvenile is dark brown overall, with blacker head and upperneck. There is a variable amount of white in both juvenile and immature plumages. The facial skin is dull and the legs are blackish.

The Rock Shag occurs on both Pacific and Atlantic coasts of S South America, in Tierra del Fuego and in the Falklands.

The Rock Shag breeds on the ledges of steep, bare rocky cliff faces. It feeds inshore and prefers cold waters. It frequents coasts, islands and channels.

The Rock Shag is silent outside the breeding season. However, they become more vocal during displays. Usually, males are more vocal than females. They produce croaking, groaning, barking and gargling sounds. The female produces softer sounds such as hissing or puffing sounds.

The Rock Shag feeds on small fish, crustaceans and cephalopods. The benthic fish is an important part of its diet all year round.
It feeds solitary and typically performs pursuit-diving. It forages close to the shores and especially in kelp beds. It dives to depths of less than 15 metres, usually between 5 and 10 metres, in search of preys and pursues them underwater.   

During the breeding season, the Rock Shag performs courtship displays. The male usually displays from the nest-site. We can observe wing-waving, with the bill pointed upwards and forwards, in order to enhance the head pattern. Another display, the “gargling”, shows the male throwing the head back, until the nape touches the rump. Displays are accompanied by vocalizations.
The displays end when a female comes close to the male and is accepted. Then, greeting displays are performed by the male, and the pair repeats this behaviour during breeding. Copulation occurs at nest-site.

The Rock Shag is sedentary in the Falklands and remains around the islands all year round. The mainland shags perform some dispersal after breeding. They can reach the northern limit of their breeding range, sometimes N as far as Uruguay. The populations of Tierra del Fuego winter on Patagonia’s coasts.

The laying occurs between October and December, mainly November in the Falklands.
The Rock Shag usually forms small colonies, established on rock, with the nests built on cliff ledges. The nest is made with seaweed and vegetation, held together with excreta and mud.

The female lays 2-5 eggs. The chicks fledge during January and February. They remain at nest until they fledge. They are fed by regurgitation by their parents, including after fledging.

The Rock Shag is not abundant, but this species can be locally common in Chile and S Argentina. The breeding colonies established on steep cliffs are naturally protected, although the increase of human disturbance is a growing problem, and involves a reduction in breeding success. The adults may abandon the nest with eggs or chicks which become vulnerable to predation.
The Falkland’s population is estimated at about 60,000 breeding pairs. The mainland population size is unknown.  
But currently, the Rock Shag is evaluated as Least Concern.