Kerguelen Shag
Leucocarbo verrucosus

Suliformes Order – Phalacrocoracidae Family

INTRODUCTION:
The Kerguelen Shag is often considered a subspecies of the Imperial Shag (Leucocarbo atriceps), but it differs by its small size and shorter bill, more rounded wings, all black upperparts (with no white on wings or back), dull brownish legs and feet and bluish-grey eyering.
It is endemic to Kerguelen Islands in S Indian Ocean. It breeds in colonies along the coasts of some islands of the archipelago, and forages in open inshore waters.
The Kerguelen Shag is not globally threatened but it has fairly small breeding range.

DESCRIPTION OF THE BIRD:
Biometrics:
Length: 65 cm
Wingspan: 110 cm
Weight: 1700-2240 g

The Kerguelen Shag adult has black head, hindneck, upperparts (including wings and tail) and outer part of the thighs, with blue gloss becoming mostly bronzy green on scapulars and upperwing.
The underparts are white, including chin, throat, lower cheeks and neck sides. The underwing is blackish with brownish wash.
On the head, we can see a long, erectile black crest formed by several up curved feathers on crown. The head is black from crown to malar area, with greenish-blue gloss.

During the breeding season, there are some white filoplumes above and behind the eye. The crest is usually lost as the breeding season progresses, like the filoplumes. The plumage becomes duller too.
We can see conspicuous warty yellow caruncles on the sides of the forehead. Gape, base of mandibles and gular pouch are dark brown, and the bare skin is densely covered with numerous tiny yellow tubercles.
The eyes are dark brown, surrounded by broad, blue eyering. The bill is dark grey with brown tinge and paler at tip. Legs and webbed feet are pink with dark areas on joints and webs.  

Outside the breeding season, the caruncles become smaller and dull orange-buff, and the eyering is duller. The facial skin is paler and duller.    
Male and female are similar. The Kerguelen Shag resembles other “blue-eyed” shags but it is smaller.  

The juvenile has dark brown upperparts and a variable amount of dark brown on the underparts. The eyes are brown. The caruncles are absent. The facial skin is dull and legs and feet are brownish.
The immature has more glossy plumage and gradually acquires the white underparts.

RANGE:  
The Kerguelen Shag is endemic to the Kerguelen Islands in S Indian Ocean, one of the most remote areas on Earth. It nests on the main island of the archipelago (Grande Terre), on some offshore islands and on islands in the Golfe du Morbihan (Kerguelen), on the E coast of Grande Terre.

HABITAT:
The Kerguelen Shag nests on exposed stretches along the coasts, but also in more sheltered areas. It forages at sea throughout the islands of the archipelago, often in bays or inlets, usually within six kilometres of the shore. During summer, if feeds among kelp.

CALLS AND SOUNDS:
The Kerguelen Shag male is more vocal than the female, and usually makes croaking, groaning and growling. The female produces softer hissing sounds.

BEHAVIOUR IN THE WILD:
The Kerguelen Shag feeds on fish and aquatic invertebrates such as echinoderms, crustaceans and marine worms. Like all Phalacrocoracidae, it feeds mainly by pursuit-diving underwater.
During the breeding season, it usually forages alone, but outside this period, they feed in large flocks, forming linear flocks of several hundred individuals.
Some of them feed on introduced brown trout (Salmo trutta) and brook char (Salvelinus fontinalis) in freshwater lakes on Kerguelen.  

The Kerguelen Shag breeds in colonies of 30 to 400 pairs, depending on the island. The male performs the typical courtship displays such as “Gargling”. It throws its head back until the nape touches the rump, while the bill is wide open. This display is accompanied by calls. Both adults share the nesting duties. They are monogamous.

The Kerguelen Shag is sedentary and only disperses throughout the islands of the archipelago after the breeding season. Some immature birds are recorded up to 80 kilometres from the islands, over the continental shelf. But most colonies are often occupied year-round.  
The Kerguelen Shag has powerful flight with regular, continuous wingbeats, sometimes interspersed with glides.

REPRODUCTION OF THIS SPECIES:
The egg laying period varies depending on the colony. It usually occurs between September and January, with peak in October/November. The colonies may include 30 to 400 pairs, and they are sometimes established close to penguin colonies.
The nest is a truncated cone made with grass and seaweeds, cemented together with mud and guano. It is generally built on cliff ledge or in rock crevice. It can be reused in several following years if not destroyed.

The female lays 2-4 eggs and both adults share the incubation during about one month. At hatching, the chicks are naked, but a dark brown down growths very soon.  
They are preyed upon by skuas, gulls and sheathbills, in spite of heavy protection by their parents.  

PROTECTION / THREATS / STATUS:   
The Kerguelen Shag is considered fairly abundant throughout its restricted range. It is not globally threated outside the natural predation.
The population is estimated at 12,000 pairs and appears to be stable.
The Kerguelen Shag is currently evaluated as Least Concern.

Fr: Cormoran des Kerguelen
Ang: Kerguelen Shag
All: Kerguelenscharb
Esp: Cormorán de las Kerguelen
Ita: Cormorano delle Kerguelen
Nd: Kerguelenaalscholver
Sd: kerguelenskarv

Text by Nicole Bouglouan

Sources:

HANDBOOK OF THE BIRDS OF THE WORLD vol 1 by Josep del Hoyo-Andrew Elliot-Jordi Sargatal - Lynx Edicions - ISBN: 8487334105

A Complete Guide to Antarctic Wildlife by Hadoram Shirihai and Illustrated by Brett Jarrett - Edited by Guy M. Kirwan - ALUL.A Press Oy, Finland - ISBN 9519894705

Avibase (Denis Lepage)

BirdLife International

HBW Alive

Wikipedia, the free encyclopaedia

Freshwater fishing in seabirds from the sub-Antarctic Kerguelen Islands

 

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