A skua is a type of seabird native to the arctic areas of most continents. These birds are usually gray and white in color with black bills, although some species are brown. Skuas are relatively large birds and might grow to lengths of up to 18 inches (about 46 cm) and weigh as much as 1 to 2 pounds (about 0.5 to 1 kg). Most skuas have wingspans of roughly 49 inches (125 cm). The large size of the skua usually makes flying slightly difficult for them, and they tend to flap their wings often while in flight rather than gliding through the air.
The skua is a predatory bird that normally prefers to spend most of its time at sea. These birds are not usually seen around the shoreline unless they are breeding, which usually occurs in the summer. Skuas often steal their prey from other birds in midair. These birds do not always attack alone and frequently team up against other birds to steal their prey. Some of the birds that skuas often steal from include puffins and terns, and they might occasionally raid the nests of these birds in search of eggs and other food. Larger skuas even will hunt and eat other adult birds.
After mating occurs in the summer, the female skua lays about two eggs in a safe area, such as under rocky shelter or up on grassy plateaus, which may be very close to the same areas where penguins build their nests. Unlike many other types of birds, skuas do not normally build nests; they generally prefer to lay their eggs in small depressions made in the ground. The eggs may be incubated for approximately one month before the young skuas hatch, which normally occurs in December or January.
Adult skua birds are very aggressive, and they will fight to the death if necessary to protect their young and nesting areas from potential predators. When the young birds leave the nest, they normally stay at sea until they are old enough to breed. The skua typically reaches sexual maturity by the age of two years.
Skuas are not considered an endangered species, though their numbers may have dropped slightly in some areas because the population of one of their primary food sources, a bird called a burrowing petrel, is on the decline. The average life span of the skua is roughly 11 years, but can be longer in the right environment. Most skuas, however, don't live until the 11-year mark because of their violent, aggressive lifestyles.