Black-legged Kittiwake Life History
HabitatOceans
NestingCliff
BehaviorDabbler
Black-legged Kittiwakes nest in dense colonies on ledges of seaside cliffs, on islands, headlands, and other sites free of mammalian predators. A few have also nested on shipwrecks or abandoned buildings. During the breeding season, they forage up to 30 miles from the nest, hunting both over continental shelf waters and deeper waters to feed their chicks. In the nonbreeding season, kittiwakes have a wide distribution, from the edge of sea ice southward. They forage mostly over cold water, often over seamounts, banks, or the continental slope (shelfbreak), as well as along fronts where currents meet. Such features tend to concentrate prey species. When not breeding, kittiwakes seldom come to land, although juvenile kittiwakes often appear singly on ocean beaches and at large inland lakes and reservoirs in autumn, usually during or after a strong storm. Unlike many North American gulls, they do not visit landfills.
Black-legged Kittiwakes eat mostly small fish, which they grab from the surface or just below, usually by dipping or plunging into the water from low flight. They sometimes seize prey while sitting on the water or even by chasing prey underwater (to depths of 3 feet). They also eat small squid; zooplankton including euphausiids, amphipods, and copepods; marine worms (polychaetes); and jellyfish. They swallow prey whole. They sometimes forage around feeding whales or active fishing vessels, which bring prey items nearer the surface. Kittiwakes tend to concentrate in large numbers where prey is abundant. During the breeding season, they occur in mixed-species flocks of seabirds that may include many thousands of auks, cormorants, terns, and other gulls. Kittiwakes are often the first species that discovers a patch of prey, and other seabirds are quickly attracted. Larger gulls and jaegers often target kittiwakes, harassing them in flight and stealing their food. Kittiwakes also regularly steal food in this manner from other kittiwakes. They hunt mostly during daylight hours but sometimes hunt nocturnally when prey such as lanternfish are available. Other prey species include Pacific sandlance, capelin, Pacific herring, walleye pollock, Arctic cod, saffron cod, anchovy, and opalescent inshore squid.
Males select narrow ledges of seaside cliffs for nest sites, rarely similar human-made structures, often among murres or other auks. Nesting on the ground has been observed in Alaska where no ground predators were present.
Both male and female construct a bowl-shaped platform of mud, grass, and marine vegetation, sometimes including feathers. Nests average about 17.7 inches across, with interior cup about 9.8 inches across.
Brown, blue, gray, olive or tan, with dark brown-gray speckling.
Alert and mobile, covered with white and gray down.
Black-legged Kittiwakes return to nesting areas in spring, as their prey species also move northward. Males arrive ahead of females, claim their previous nest site, and begin displays as females arrive. In some colonies, up to 82% of the returning adults re-partner with the mate from the previous nesting season. Male courtship display involves extending the neck, then bringing the bill to the breast and quickly raising the bill skyward several times. Unmated females in search of a mate are attracted to males engaged in this display, which almost looks as though the bird is trying to swallow something—hence it is called the "choking" display. Mates also give this display when they exchange duties at the nest and when coming into conflict with other kittiwakes over nest sites. Males defending a nest site also extend the neck, raise the body, partially close the eyes, and face the rival with open bill, making a cooing sound and shimmying the body. Unlike other gulls, kittiwakes attack one another by grasping the bill and twisting the opponent. During the establishment or maintenance of pair bonds in spring, male and female greet one another with nodding, head-bobbing, and crossed necks. In the week or so before the first egg is laid, females often beg food from males in a submissive posture, like a chick; males respond by regurgitating food. Kittiwakes are monogamous in their mating system, and studies have demonstrated that extrapair paternity is rare. Both parents incubate the eggs and feed and defend the chicks. After the breeding season, adults and young disperse to sea.
Partners in Flight estimates a global breeding population of 10 million birds and rates the species an 8 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. In 2002, the North American Waterbird Conservation Plan estimated 3,126,000 breeding birds in North America. Long-term studies in the United Kingdom and Iceland indicate that Black-legged Kittiwake populations are in rapid decline in these areas. Warming sea temperatures, which reduce plankton vital to the food chain, are believed responsible for the rapid decline in kittiwakes as well as Arctic Terns, Atlantic Puffins, and some auk species.
Hatch, Scott A., Gregory J. Robertson and Pat Herron Baird. (2009). Black-legged Kittiwake (Rissa tridactyla), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
Red-legged Kittiwake