Skua

What are the defining characteristics of skuas as a bird group?

Skuas are predatory seabirds belonging to the family Stercorariidae within the order Charadriiformes. While the term “skua” is used broadly, in the United States, the three smaller species in this family are typically referred to as jaegers.¹²

Defining characteristics of this group include:

• Physical Appearance: Skuas are heavily built, gull-like birds characterized by hooked bills. They are agile and swift fliers, spending much of their time on the wing.¹³
• Feeding Behavior: They are well-known as “pirates” of the sea; they frequently harass other birds, such as terns, gulls, and boobies, forcing them to disgorge or drop their food, which the skua then retrieves.³
• Diet: Beyond piracy, they are opportunistic predators. On their breeding grounds, they consume insects, rodents, carrion, and the eggs or young of other seabirds, such as penguins and petrels.¹³²
• Distribution: The great skua is notable for being the only bird that breeds in both the Arctic and the Antarctic.¹

How do skuas differ from their close relatives, the jaegers?

The distinction between skuas and jaegers is primarily a matter of regional terminology and size, as both groups belong to the same family, Stercorariidae.⁴²

In the United States, the name “skua” is typically reserved for the larger, more robust species—specifically the great skua (Catharacta skua)—while the three smaller species in the genus Stercorarius are referred to as jaegers.⁴ In Britain, however, all of these birds are commonly referred to as skuas.²⁴

Key differences include:

• Size and Build: The great skua is a heavily built bird reaching about 60 cm (24 inches) in length. In contrast, the three jaeger species are smaller, ranging from 35 cm (14 inches) for the long-tailed jaeger to 50 cm (20 inches) for the pomarine jaeger.²⁴
• Appearance: Jaegers often exhibit two distinct color phases (all-brown or brown above and white below) and are characterized by projecting central tail feathers.⁴
• Range: The great skua is unique for being the only bird that breeds in both the Arctic and the Antarctic. Jaegers primarily nest in the Arctic tundra before migrating to sea.²⁴⁵

What are the breeding habits and nesting behaviors of skuas?

Skuas, which belong to the family Stercorariidae, exhibit specific breeding and nesting behaviors adapted to their predatory nature. While they are not considered strongly colonial, they often choose nesting sites in close proximity to other seabird colonies, such as penguins, petrels, and terns. This strategic placement allows them to easily access the eggs and young of these birds as a food source.¹²

In specific regions, such as Iceland, skuas have been observed nesting in clumps of vegetation located on large outwash gravel plains. Their close relatives, the jaegers, typically nest on the Arctic tundra, where both parents share the responsibility of incubating their two eggs.²

Because skuas are highly agile and aggressive, they actively defend their nesting territories. Their tendency to nest near other species is a key part of their opportunistic feeding strategy, as they frequently steal food from neighboring birds in addition to preying upon their offspring.¹

What is the taxonomic classification of skuas within the bird family?

Skuas and their close relatives, the jaegers, are classified within the bird family Stercorariidae. This family is part of the order Charadriiformes, which encompasses a diverse group of birds including gulls, terns, and shorebirds.⁶¹⁴⁷

Within the broader taxonomic structure, the family Stercorariidae is placed in the suborder Lari. In some taxonomic classifications, the group is occasionally ranked as a subfamily of the Laridae (the gull family). These predatory, long-winged seabirds are found in high latitudes across both hemispheres and are widely distributed throughout the world’s oceans.⁷⁸