The Black-legged Kittiwake (Rissa tridactyla) is a smaller seagull. It is mostly pure white, small pointed bill, short black leggs, grey back and wings and most important: black beady eyes. This gull owes excellent flying abilities and can fly at extreme speed, even faster than the Northern Gannet, at least from my point of view.
The Kittiwake spends most of the year out on the Atlantic and only returns to shore for breeding. Breeds colonial on cliff ledges. It southernmost colonies are in northern Spain and in Portugal. A colony also exists on the German island of Heligoland in the southern North Sea (German Bight).

Characteristics of the Black-legged Kittiwake
Taxonomy
Order: Charadriiformes
Family: Laridae
Genus: Rissa
Species: Black-legged Kittiwake
Scientific Name: Rissa tridactyla
Names and Synonyms of the Black-legged Kittiwake
German: Dreizehenmöwe
Czech: Racek tříprstý
Slovak: Čajka trojprstá
Hungarian: Csüllő
Croat: Troprsti galeb
French: Mouette tridactyle
Spanish: Gaviota Tridáctila
Portuguese: Gaivota-tridáctila
Dutch: Drieteenmeeuw
Italian: Gabbiano tridattilo
Iceland: Rita
Faroer: Rita, Ryta
Greenland: Nowyavah, Taateraaq
North Sami: Skierru
Finnish: Pikkukajava
Danish: Ride
Swedish: tretåig mås
Polish: Mewa trójpalczasta
Russian: Моевка
Japanese: ミツユビカモメ

Distribution of the Black-legged Kittiwake
The Kittiwake enjoys a circumpolar distribution, holarctic distribution at the shorelines of temperate zones and down south to 47° N. Also high arctic. In Europe from southwest to northwest. In the northwest only on Heligoland and in northern Denmark. Also on Greenland, Iceland, from western Russia to east Siberia, Alaska and Canada.
Movements and Wintering
Movements: European breeders usually live in the North Atlantic, from the pack ice edge down south to the Sargasso Sea. Breeders from Greenland move to west Europe.
Wintering: most important winter areas are: from the North Atlantic pack ice edge southwards to the Sargasso Sea, Azores, western Mediterranean, eastern Mediterranean to Aegian Sea; Western Europe, Ireland (Republic), Great Britain, shorelines of Belgium, the Netherlands, Germany and Denmark (Wadden Sea).
Behaviour
The Kittiwake is fully adapted to a life on the ocean, only returning to land for breeding. Colonial breeder on cliffs and on small rocky islands. Rare winter guests inlands. Activities both diurnal and nocturnal. During breeding feeding flights mostly at night.

Measurements of the Kittiwake
Size: 37-42 cm
Weight:
♂: 350-500 g
♀: 310-470 g
Wingspan: 91-120 cm
Wing:
♂: 29.0-32.6 cm
♀: 27.9-31.8 cm


Breeding
Maturity: first appearance in colony from 2nd to 7th year. First breeding between 3-8 years.
Mating Season: monogamous seasonal breeding pair. Mating in colony, initiated by ♂. Re-mating with previous partner possible.
Clutches per breeding season1 clutch
Breeding: Begin of laying at centre of colony as of early May. More northern breeders from mid May to early June. On the peripheries of the colony laying starts usually 3.5 days later. Laying during day and night. Breeding between May and July
Nest: Earth and mud form the foundations of the nesting site only sparsely lined with material assembled in the surroundings. Nest building starts long before laying. Nest sits on cliff ledges and small outcrops. On the bird cliff Kittiwakes usually nest above the Black Guillemots and Cormorants.
Clutch – Eggs – Measurements of the Kittiwake
Clutch: (2-) 2 (rarely -3) eggs
Eggs: crème-coloured broad-oval mostly fleckless egg, though speckled eggs are not uncommon.
Egg Measurements:
Length: 47.1-61.5 mm
Width: 34.5-44.5 mm
Ø: 54.6×40.1 mm (n=479)
Egg weight: 40.0-63.0 g
shell weight: 2.33-3.68 g; Ø 2.92 g g

Laying – Incubation – Fledging and Dependency
Recurrent Clutch: possibly when clutch is lost during early days.
Laying Interval: 48 hours.
Begin of incubating: after first egg.
Incubation: 25-32 (35) days, both parents share the task of incubating. It takes 27.2 ±0.7 days from laying the last egg to the last chicken hatching
Hatching: The interval between first and second chicken is 1.3±0.7 days. It takes 2.3±0.97 days from first crack in the shell to first piercing the first hole into the shell; from there to final hatching it takes another 1.0±0.62 days .
Fledging: after 42 days the juvenils finally leave the nest, both parents care for the nestlings.
Dependency: After 30 days have only little ability to fly; after 34-36 days they have gained full flight ability. After leaving the nest juveniles are fully independent.

Miscellaneous
Food: Black-legged Kittwakes feed on small fish, sandeels mollusks, crustacean.
Longevity: The oldest known ringed bird of a Kittiwake reached an age of 28 years and 5 months.
Mortality: From all layed eggs only 24 % of the juveniles reach the 5th year, whereas adult Kittiwakes have a survival rate of c. 86% per annum.
Threats: Large Gulls, disturbances at the colony, overfishing of the seas, fishing and processing of small fish such as sandeels, leading to a massive reduction in available food. Also perishing in fishing nets. Absorption of heavy metals from dietary sources. General deterioration of habitats.

References
Bauer, Hans-Günther, Bezzel, Einhard et. al. (HG), Kompendium der Vögel Mitteleuropas, Band 1+2, Sonderausgabe 2012, Aula Verlag, Wiebelsheim
Bauer, Hans-Günther, Bezzel, Einhard et. al. (HG), Kompendium der Vögel Mitteleuropas, Band 3, Literatur und Anhang, Aula Verlag Wiebelsheim, 2. vollständig überarbeitete Auflage 1993
Bezzel, Einhard, Kompendium der Vögel Mitteleuropas, Non-Passeriformes, Band 1, AULA-Verlag Wiesbaden, 1985
Bruun/Singer/König/Der Kosmos Vogelführer, Franck’sche Verlagshandlung Stuttgart, 5. Auflage 1982
Glutz von Blotzheim, Urs et. al (HG), Handbuch der Vögel Mitteleuropas, Band 8/1, Charadriiformes (3. Teil), Akademische Verlagsgesellschaft Wiesbaden, 1982
Svenson, Lars et. al, Der Kosmos Vogelführer, Franck-Kosmos Verlag GmbH & Co. KG, Stuttgart, 2. Auflage 2011
Bundesamt für Naturschutz: Nationaler Vogelschutzbericht 2019 gemäß Artikel 12 Vogelschutzrichtlinie, Berichtsdaten aus dem Abschnitt Bl…E Brutvögel (pdf download)
- National Bird Protection Report 2019 Section Bl … E – Breeders – Wintering Birds – Migrating Birds (Text in German)


Image Credits
Egg of the Black-legged Kittewake – Source: by ©Klaus Rassinger und Gerhard Cammerer, Museum Wiesbaden – own works, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=37703474
Featured image and all other images of the Black-legged Kittiwake: by ©Raymond Loyal


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