Are skuas in Antarctica?

At first glance, the skuas you encounter in Antarctica may look like dark-winged gulls. But appearances can be deceiving. In fact, skuas are one of the most avian predators in Antarctica. There are two species of skuas in Antarctica, the brown skuas and the Antarctic skuas. Both roam King George Island in the South Shetland Islands as well as the nearby Antarctic Peninsula in search of prey.

Brown skuas are the larger of the two species and have brown bodies, sharp hawk-like bills, and small claws on the ends of their webbed feet. Antarctic skuas, the smaller of the two, have distinctively tan plumage and are more reserved than brown skuas.

Brown skuas and Antarctic skuas share common breeding rituals. Each pair of skuas in Antarctica has its own distinct breeding territory that they occupy during the breeding season. Once a breeding pair has established its territory, the pair digs a small depression in the ground to lay their eggs. The skuas then take turns incubating the eggs. One skuas sits on the nest, while the other patrols the penguin colonies in search of forage for fish or prey. The main concern about skuas' eggs is that a stray skuas could pose a threat to them, leading to a change in breeding season.

Skuas are fitted with satellite tags to track how far they travel to find food and how long those trips take. This information helps scientists understand the skuas' ecology and help conserve their populations in Antarctica. GLS (Global Location Tracking) tags can track when skuas have landed in the water, when they are in flight, and when they are on land. The information stored on the tags can be converted into detailed maps to show their exact movements. But first, the tags must be placed on the skuas, which means scientists must capture them.

The keen intelligence of Antarctic birds doesn't make it easy. A monofilament loop with a backing net is the best tool. The monofilament loop is placed on the ground in the skuas’ territory and surrounded by raw meat to attract the birds. When the skuas’ legs appear inside the loop, the wire is pulled tight and the skuas are trapped. The GLS tag is attached to the skuas’ legs, and the bird is then released. Two weeks later, it’s time to retrieve all the information collected. This means that scientists now have to return the skuas. Fortunately. Sometimes skuas outrun scientists, flying away with the transmitter. Fortunately, the transmitter is harmless to the bird and eventually falls off.

As mentioned, skuas are highly intelligent and have been known to take defensive measures against researchers they don’t like. Researchers who consistently wear the same clothes, bags, or even sunglasses can be identified and attacked when they visit the nesting grounds. These skuas’ attacks are not pleasant. Parent skuas first make “alarm calls,” loud sounds that alert other parents to an intruder. They then charge at the intruder in unison, pecking at the head and face, grabbing at clothing, and diving. 

While skuas’ eggs are still incubating, scientists record their length, width, and weight. The size and weight of the egg can be an indicator of the health of the parents. Scientists keep records of how long a skuas’ egg incubates, and based on that, they can estimate the hatching date within two to three days. When the chicks hatch, scientists attach metal bands with a unique numerical code to their legs that they wear for the rest of their lives. With any luck, the tethered skuas will return to their breeding grounds next year and raise their chicks.