Gulls, Terns and Jaegers (Laridae)
The family Laridae is very large and encompasses three subfamilies: gulls (Larinae), jaegers (Stercorcariinae), and terns (Sterninae)- a total of 92 species worldwide. Although they are all seabirds, the three subfamilies have some important differences.
Gulls are easily recognized by their shrill calls, which are often heard by the shores of the ocean. Their plumage is typically white or pale grey, with some species having black backs, wings or heads. Gull species are often hard to identify, and can sometimes only be distinguished from each other by the colour of their legs or the markings on their bills. Immature gulls of most species go through several different plumages over the course of 2-4 years, before they reach adulthood. These grey, brown and white juveniles are often impossible to identify with certainty.
Gulls are stout-bodied birds with long, pointed wings for sustained, manoeuverable flying, and webbed feet, an adaptation for life on the water. In the past 50 years they have spread inland in many countries, but in the Arctic they remain coastal species. However, Arctic gulls do share the ability of temperate gulls to exploit the presence of humans, congregating around any settlement with a garbage dump! Even away from the presence of humans, gulls are naturally scavengers, eating all kinds of carrion. Most members of this subfamily nest in large colonies on coastal cliffs, with both parents helping to raise the offspring.
Jaegers are dark-coloured, gull-like birds with long, pointed wings, strongly hooked beaks, and well-developed claws on their webbed feet. Jaegers are seabirds and hunters, using their graceful, acrobatic flying ability to acquire food. Some species are “parasitic”- they chase kittiwakes and gulls before they have had a chance to swallow prey which they have captured. The jaegers then steal this food, swooping down to catch the meal before it falls into the sea below. The ranges of the three Arctic jaeger species overlap, and they can often be found breeding in the same area. All three species nest on the tundra. Both parents care for the two eggs, defending their nest at all costs. These birds are aggressive- when another bird or animal comes near, the nesting jaeger flies up behind it and pecks at its head, or hits it with its feet. They also sometimes dance around in a distraction display to draw predators away from the nest. The parent jaeger mimics an injured bird, enticing a fox to try to catch it instead of stealing its nutritious eggs.
Terns are the acrobats of the gull family. They are smaller and slimmer than gulls, with streamlined bodies, narrow, elbowed wings and deeply-forked tails which allow them to manoeuvre through sharp turns and dives. Like gulls, they are often hard to identify- most terns have white bodies and wings and a black cap, which is sometimes replaced by white in the winter. The colour of their bills ranges from yellow and red to black, and is a useful field mark. Unlike gulls, terns are capable of hovering in the air, remaining in one place as they scan the water for fish. They feed by diving straight down to catch fish swimming near the surface. Gulls often swim on the surface of the water, but even though terns do have webbed feet, they swim less frequently, and spend most of their time in the air instead.