Skuas, sometimes known as jaegers, are predatory seabirds known for their opportunistic and aggressive foraging behaviors. These medium-to-large birds resemble dark, powerfully built gulls and occupy a high position in the marine food web. Their diet is highly variable, shifting based on geographic location, prey availability, and the time of year. This flexibility allows skuas to thrive in harsh environments, from the Arctic tundra to the Antarctic ice floes.
Kleptoparasitism: Stealing from Other Birds
The most distinctive foraging strategy employed by skuas is kleptoparasitism, the practice of stealing food from other birds. Skuas aggressively pursue birds that have already captured a meal, such as gulls, terns, puffins, and gannets, chasing them relentlessly until the victim drops or regurgitates its catch mid-flight.
Skuas use aerial tactics, often flying directly at the target or making physical contact. This harassment forces the bird to disgorge the food item, which the skua then expertly snatches before it hits the water. This strategy conserves energy, and for some species, it accounts for up to 95% of their total nourishment during winter months.
Active Predation of Live Prey
Skuas actively prey on a variety of live animals in their respective environments, and this hunting behavior often intensifies during the breeding season when they provision their young. A significant portion of this predation focuses on the young of other seabirds, particularly in large colonies.
In polar regions, skuas regularly patrol penguin colonies, preying upon the eggs and vulnerable chicks. They seize unattended eggs or snatch small chicks when parents are distracted. Larger skua species, such as the Great Skua, are capable of killing and consuming adult seabirds, including puffins and gulls.
Skuas also hunt small terrestrial animals near their nesting grounds, frequently feeding on lemmings and other rodents when they are abundant on the tundra. Another element is that they hunt marine life by catching small fish, krill, and invertebrates directly from the water surface, especially during migration.
Opportunistic Scavenging and Adaptability
The skua’s diet is further broadened by its remarkable adaptability, which includes extensive opportunistic scavenging of dead or discarded food items. This flexibility is a survival mechanism that allows them to endure periods when active hunting or stealing is less productive. They regularly consume carrion, feeding on the remains of dead seals, whales, and other marine life washed ashore.
Skuas are often seen scavenging around large breeding colonies, taking advantage of carcasses left by other predators or consuming dead, abandoned chicks. Near human activity, they readily utilize anthropogenic food sources, including fishery by-catch discarded by fishing vessels. This willingness to consume offal and kitchen refuse near settlements provides a reliable supplementary food source.