The black-legged kittiwake (Rissa tridactyla ) is a seabird species in the gull family Laridae.
This species was first described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae as Larus tridactylus. The English name is derived from its call, a shrill 'kittee-wa-aaake, kitte-wa-aaake'. The genus name Rissa is from the Icelandic name rita for this bird, and the specific tridactyla is from Ancient Greek tridaktulos, "three-toed", from tri-, "three-" and daktulos, "toe".
In North America, this species is known as the black-legged kittiwake to differentiate it from the red-legged kittiwake, but in Europe, where it is the only member of the genus, it is often known just as kittiwake.
A piscivore is a carnivorous animal that eats primarily fish. Piscivorous is equivalent to the Greek-derived word ichthyophagous. Fish were the die...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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CongregatoryCongregatory animals tend to gather in large numbers in specific areas as breeding colonies, for feeding, or for resting.
Oviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
Precocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
Soaring birds can maintain flight without wing flapping, using rising air currents. Many gliding birds are able to "lock" their extended wings by m...
Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, b...
Monogamy is a form of relationship in which both the male and the female has only one partner. This pair may cohabitate in an area or territory for...
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MigratingAnimal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migrati...
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starts withThe adult is 37–41 cm (15–16 in) in length with a wingspan of 91–105 cm (36–41 in) and a body mass of 305–525 g (10.8–18.5 oz). It has a white head and body, grey back, grey wings tipped solid black, black legs and a yellow bill. Occasional individuals have pinky-grey to reddish legs, inviting confusion with red-legged kittiwake. The inside of their mouth is also a characteristic feature of the species due to its rich red colour. Such red pigmentation is due to carotenoids pigments and vitamin A which have to be acquired through their diet. Studies show that integument coloration is associated with male's reproductive success. Such hypothesis would explain the behavior of couples greeting each other by opening their mouth and flashing their bright mouth it to their partner while vocalizing. As their Latin name suggests, they only possess three toes since their hind toe is either extremely reduced or completely absent. The two subspecies being almost identical, R. tridactyla pollicaris is in general slightly larger than its counterpart R. tridactyle tridactyla. In winter, this species acquires a dark grey smudge behind the eye and a grey hind-neck collar. The bill also turns a dusky-olive color.
Since kittiwakes winter at sea and rarely touch ground during this period, very little is known about their exact molting pattern.
At fledging, the juveniles differ from the adults in having a black 'W' band across the length of the wings and whiter secondary and primary feathers behind the black 'W', a black hind-neck collar and a black terminal band on the tail. They can also be identified due to their solid black bill. This plumage is a hatch-year plumage and will only remain for their first year. Kittiwakes obtain their mature plumage at 4 years old, but will gradually change their juvenile plumage over time until maturity is reached. A second-year juvenile resembles a hatch-year regarding the plumage, though the bill is no longer solid black but instead has a greenish color. The black marking on the coverts and the tail is still visible. The black marking will only molt during their third year, where the black is no longer present on the coverts, but the grey smudge on the head remains. A third-year bird will also exhibit a small zone of bright yellow/orange at the base of its mostly greenish bill. It is only at four years old that the bill will reach an overall colour of bright yellow and complete its mature plumage.
The old fisherman's name of "tarrock" for juvenile kittiwakes is still occasionally used.
The black-legged kittiwake is a coastal bird of the arctic to subarctic regions of the world. It can be found all across the northern coasts of the Atlantic, from Canada to Greenland as well as on the Pacific side from Alaska to the coast of Siberia. Black-legged kittiwakes' wintering range extends further south from the St-Lawrence to the southern coast of New Jersey as well as in China, the Sargasso sea and of the coast of west Africa. There are two subspecies of black-legged kittiwake. Rissa tridactyla tridactyla can be found on the Atlantic coast whereas Rissa tridactyla pollicaris is found on the Pacific coast.
Out of all the laridae, the kittiwakes are the most pelagic ones. Kittiwakes are almost exclusively found at sea with the exception of the breeding period, from May to September, where they can be found nesting on the sheerest sea cliffs. They are rarely found inland, though they have been reported on few instances as far as 20 km inland. For the rest of the year, kittiwake spend most of their time on the wing out of sight from the coast.
Kittiwake are known for their graceful flight. Unlike larger gulls, their flight is light with the wings beating in fast strokes. When looking at them flying around the colony, kittiwakes often look as if they are playing in the wind with their agile flips and loops. Kittiwakes are highly gregarious and therefore are rarely seen flying alone far away from the colony.
Kittiwakes are primarily pelagic piscivorous birds. Their main food source consists of fish, though it is not unlikely to find invertebrates such as copepods, polychete and squids in their diet, especially when fish is harder to find. Due to their wide range, kittiwake diet is quite variable. In the Gulf of Alaska, their diet is usually composed of Pacific capelin, Pacific herring, Pacific sand land and much more. Kittiwakes of the coast of the United Kingdom, in Europe, rely mostly on sandeels. In 2004, the kittiwake population in the Shetland islands, along with the murre (guillemot) and tern population, completely failed to reproduce successfully due to a collapse in sandeel stock. Like most gulls, kittiwake forage at the surface of the water where they tend to catch their prey while in flight or sitting on the water. Throughout winter, kittiwakes spend all of their time at sea where they forage. Unlike some gull species, they do not scavenge at landfills.
The foraging style of the kittiwakes is often compared to the terns' foraging strategy due to their frequent hovering and their head diving quickly at the surface of the water. Instances of kittiwakes following whales are also common since they benefit from the fish fragments expelled by these huge marine mammals. Fishers and commercial fishing boats are also the frequent witnesses of big groups of kittiwakes, often mixed with other gull species and terns, hovering around their ship in order to benefit from the scraps rejected in their sewage water or thrown overboard.
There are few studies focussing on their water needs, though they seem to prefer salt water to fresh water. Captive kittiwakes are known to refuse fresh water but will willingly drink salt water.
It is a coastal breeding bird around the north Pacific and north Atlantic oceans, found most commonly in North America and Europe. Kittiwakes are colonial nesters that form monogamous pairs and exhibit biparental care, meaning that both take part in nest building, incubation and chick rearing. They tend to nest in large numbers on cliffs by the sea side. It breeds in large colonies on cliffs and is very noisy on the breeding ground. Cliff nesting for gulls occurs only in the Rissa species, and the kittiwake is capable of utilizing the very sheerest of vertical cliffs, as is evident in their nesting sites on Staple Island in the outer Farne Islands. There are few instances of kittiwakes nesting on man-made structure in Europe and Alaska. Kittiwake pairs both participate in building the nest in which the female will lay their eggs. The breeding season begins in mid-June and usually end in August.
Building the nest in order to welcome their fragile eggs is a tedious task and requires time and energy. The parents begin with a layer of mud and grass in order to form a platform that will cushion and help to isolate the eggs from the cold ground. A cup is then built around the platform in order to keep the eggs from rolling out of the nest. Finally, the nest is lined with soft and dry material such as moss, grass or seaweed. The nest is solidified by a continuous trampling of the materials by the pair. Throughout this period, the male will do courtship feeding by feeding the female at their nest site. The reasons for such behavior are not quite understood but many hypothesis have been brought up to explain the phenomenon. Hypothesis such as the "nutrition hypothesis" and the "copulation enhancement hypothesis" have shown evidence that this behavior evolved either through natural or sexual selection.
Kittiwakes are single-brooded, meaning that the pair will only reproduce once per year. Egg formation within the female usually takes around 15 days and normal egg clutch size ranges from one to two sub-elliptical eggs, though three eggs clutches are not impossible. The female will lay eggs on alternate days. The eggs' color varies quite a bit, ranging from white, brownish to turquoise with dark brown speckles. Once the eggs are laid, the parents will take turns and incubate their clutch for an average period of 27 days. In case of egg loss, the female might relay another egg within 15 days after the loss.
Since the 1970s, its it believed that the global population of black-legged kittiwake has declined of about 40% in only three generations (one generation is in average 12.9 years), putting the species in a dangerous place for the future. The global population is estimated at 14,600,000-15,700,000 individuals and is in constant decline. The individual distribution of kittiwakes across the world varies quite a bit, with Europe representing more than 50% of the world's kittiwake and North America representing only 20%. In their recent species assessment, the IUCN Red List pointed out that all but one populations of kittiwakes were in decline, with the exception of the small Canadian arctic population that seems to be increasing at a rate of 1% per year. The last IUCN Red List report in 2017, the species was moved from "least concern" to a "vulnerable" status on a global scale.
There are still no global conservation plans for the black-legged kittiwake though the species is closely monitored for population trends shifts. There are currently no international legislations regarding this species. However, the black-legged kittiwake is protected under the Migratory Bird Treaty Act of 1918 that has been ratified by the US, Canada, Mexico, Russia and Japan. As for many gull species, the kittiwake is not a species of special interest for the public, therefore there are no education plans put in place in order to inform and educate people regarding this species.
Social animals are those animals that interact highly with other animals, usually of their own species (conspecifics), to the point of having a rec...