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South Polar Skua typically lay two eggs. The chicks are precocious and within a few hours of hatching are able to walk on there own are around there territory., Cape Bird, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

During the summer skuas often nest near penguin colonies. Proximity to the colonies allows them to opportunistically prey on unguarded chicks and eggs, with which they feed their own young., Cape Bird, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

Adult skua have a very strong bill with a pronounced hook at the tip. This aids them in aggressive foraging and defence of their nesting territories., Cape Bird, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

South Polar skua live on open scree slopes, usually in close proximity to penguin colonies, Cape Bird, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

The south polar skua is a large predatory seabird and has an average wing span of 1.3 metres., Cape Bird, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

The smaller south polar skua have an average wing span of 1.3m and breed around he continent., Cape Bird, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

South Polar skua have heavier bodies than their gull relatives, with a strong hook shaped bill., Cape Bird, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

The adult plumage of the south polar skua occurs in three distinct colour forms. Individuals may have pale, medium or dark plumage. This image shows the difference between pale versus dark individuals., Cape Bird, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

Skuas have heavier bodies than their gull relatives and stronger, more hooked bills, reflecting their more predatory lifestyle., Cape Bird, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

South polar skua breed exclusively around the coast of Antarctica, nesting on open scree slopes, Cape Bird, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

Like many predatory birds, skuas regurgitate the less digestible components of their diet. Bones and feathers, remaining after a meal has been digested, are regurgitated in the form of a compact pellet., Cape Bird, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

Skua lay only two eggs that are laid two to three days apart, because they begin incubation immediately the eggs hatch asynchronously., Cape Crozier, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

There is no clear explanation for the evolution of sibling aggression. Experiments have shown that sibling aggression in the south polar skua is not dependent on the amount of food available to chicks during breeding season., Cape Crozier, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

Conspicuous white patches on the top and bottom of the wings are a characteristic of south polar skua plumage., Cape Crozier, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

Skua chicks must be protected from other predatory skuas and brooded regularly for the first couple of weeks after hatching., Cape Crozier, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

Penguins nest in large colonies to protect themselves from predators such as the south polar skua. As a result skua feeding is highly opportunistic., Cape Crozier, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

Dead penguin chicks are scavenged as carrion or, when the opportunity arises, taken from unguarded nests., Cape Crozier, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

Sibling aggression is more likely if a competitive disparity, such as difference in size, exists between chicks., Cape Crozier, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

The most common resut of sibling aggression is that the weaker chick is excluded from access to parental care. The result is that it will die from either exposure, starvation, or attacks from other skuas., Cape Crozier, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

Sibicide is more likely to occur in species that are predatory as adults., Cape Crozier, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

Exclusion from the nest site as a result of sibling aggression may result in the weaker chick dying from exposure when it is no longer brooded by its parents., Cape Crozier, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

One consequence of sibling aggression is that the weaker chick is deprived of parental attention and brooding, this decreases its chances of survival., Cape Crozier, Ross Island, Antarctica, Restricted to staff and students of the University of Auckland, SBSAntarctica

During breeding season adult skuas are required to stay constantly on their nest, not only to incubate the eggs and chicks, but also to defend them from other predatory skuas., South Shetland Islands (Antarctic Peninsula), Restricted to staff and students of the University of Auckland, SBSAntarctica

During breeding season skuas are highly territorial, calling displays are frequent and help to maintain territories by deterring other birds., Chatham Island, New Zealand, Restricted to staff and students of the University of Auckland, SBSAntarctica

Skuas are aggressive birds and highly territorial during breeding season, visual displays, known as long call displays, are frequently employed in territory defence., South Shetland Islands (Antarctic Peninsula), Restricted to staff and students of the University of Auckland, SBSAntarctica

The characteristic hooked bill of the skuas is due to a prominent distal 'nail' on the upper mandible. This feature is absent in gulls and is indicative of the skuas' predatory lifestyle., Chatham Island, New Zealand, Restricted to staff and students of the University of Auckland, SBSAntarctica

Wing raising and calling are employed by adult skua as part of the 'long call' display. This behaviour is commonly used to defend territories, but may also be used to greet a returning mate., Chatham Island, New Zealand, Restricted to staff and students of the University of Auckland, SBSAntarctica

Like most birds skua chicks possess an egg tooth that assists them in the difficult task of breaking out of the egg. The tooth is shed several days after hatching., Chatham Island, New Zealand, Restricted to staff and students of the University of Auckland, SBSAntarctica

The brown skua has a characteristic rich brown colouration with yellowish streaks visible in the feathers on the nape and neck., Chatham Island, New Zealand, Restricted to staff and students of the University of Auckland, SBSAntarctica

Brown skuas sometimes nest in trios, or larger groups. Most often this includes one female and multiple males defending a territory - a behaviour known as polyandry., Chatham Island, New Zealand, Restricted to staff and students of the University of Auckland, SBSAntarctica

Brown skua often select territories that includes a elevated vantage point, this vantage point is known as a roost., Chatham Island, New Zealand, Restricted to staff and students of the University of Auckland, SBSAntarctica

Flexibility and opportunism are the hallmarks of skua feeding biology., South Shetland Islands (Antarctic Peninsula), Restricted to staff and students of the University of Auckland, SBSAntarctica

Skua chicks are precocial, meaning that they are already well developed by the time they hatch, and capable of withstanding harsh conditions., Chatham Island, New Zealand, Restricted to staff and students of the University of Auckland, SBSAntarctica

Most brown skua breed on the sub-Antarctic islands or the cold-temperate islands south of New Zealand. Some brown skua breed in communal groups consisting of three or more adult birds., Chatham Island, New Zealand, Restricted to staff and students of the University of Auckland, SBSAntarctica