Black-legged kittiwake (Rissa tridactyla)
The kittiwake obtains its food on the surface and hence functions as an indicator for this part of the marine ecosystem. This pelagic gull comprises a large proportion of the sea birds, in terms of both biomass and food consumption, and is dispersed over the whole of Svalbard and the rest of the Arctic.
What is being monitored?
Cite these dataNorwegian Polar Institute (2022). Black-legged kittiwake population size, as percentage of the average in the colony. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL: http://www.mosj.no/en/fauna/marine/black-legged-kittiwake.html
|Bjørnøya||%||Norwegian Polar Institute||99||120||116||96||100||106||70||95||100||96||74||98||103||100||101||105||108||110||112||101||98||97||95||102||103||107||95||92|
|Grumant||%||Norwegian Polar Institute||108||94||117||64||151||129||136||114||100||84||76||63||87||102||95||112||96||73|
|Sofiekammen||%||Norwegian Polar Institute||91.2203||89.6199||90.3312||146.6993||81.6181||146.8771||90.1534||63.4808|
|Ossian Sars||%||Norwegian Polar Institute||70||96||125||120||88||166||104||175||116||77||123||103||84||54||50||77||78||61||98||102||90||93||132||114||109||97||107||109||103||53|
|Tschermakfjellet||%||Norwegian Polar Institute||103||115||97||126||95||146||124||122||139||63||88||119||110||83||63||149||63||59||76||112|
|Alkhornet||%||Norwegian Polar Institute||91||102||100||93||99||96||108||121||197||136||125||117||103||126||80||73||80||54||65||88||95||94||90||69|
|Fuglehuken||%||Norwegian Polar Institute||111||117||111||191||128||106||107||68||91||75||75||83||89||87||90||86||78||112||89||98||77||103||112||111||105|
|Amsterdamøya||%||Norwegian Polar Institute||104||139||120||108||125||73||42|
Monitoring of five colonies on Spitsbergen Ossian Sarsfjellet (Kongsfjorden), Fuglehuken (Forlandet) and Alkhornet, Tschermakfjellet and Fuglefjella (Isfjorden), one colony on the east side of Spitsbergen (Alkefjellet, Hinlopen) and Bjørnøya.
One to three counts of each plot (one count per observer) are made per season, from late incubating to early rearing periods. Counts are made with 10×40 binoculars.
The method is internationally standardized (Walsh et al. 1995), and is also standardized with the SEAPOP Norwegian monitoring.
All data are stored in the Norwegian Polar Institute's seabird database, as well as in SEAPOP's databases.
Reference level and action level
Red List status: a 15–30 % redction in the population over 10 years means that the species qualifies for the category "Near Threatened".
Status and trend
The Svalbard population of black-legged kittiwakes has probably increased during the last century, but most colonies in the Atlantic and Pacific oceans are declining. In Svalbard most of the monitored colonies on Bjørnøya and Spitsbergen remain stable or are even increasing slightly, after a period of decline during the 1990s. Since around 2002, most of the monitored colonies on Bjørnøya and Spitsbergen have been stable or have increased slightly. The reason for the decline in some of the colonies in Svalbard is unknown, but it has been shown that rapid heating of the ocean has a negative influence on black-legged kittiwake. Since the colonies east of Svalbard have only been monitored since 2015, the overall trend for the Svalbard population is unclear.
In mainland Norway the species is declining rapidly, and black-legged kittiwakes are since 2015 classified as Endangered (mainland) and Near threatened (Svalbard) on the Norwegian Red List.
The reason for the decline in some Svalbard colonies of kittiwakes is not known.
Considering that the overall status and trend of black-legged kittiwakes in Svalbard is unclear, the consequences for other parts of the ecosystems in Svalbard are also unclear.
About the monitoring
The black-legged kittiwake is the most numerous species of gull in the world and the most oceanic in its habits.
In Svalbard, the black-legged kittiwake is a common breeding species in all parts of the archipelago. The black-legged kittiwake is a surface-feeding bird (in contrast to other sea birds) that mainly feeds on invertebrates and small fish, but it also scavenges offal or discarded fish behind fishing boats. Chicks are fed regurgitated food. In Svalbard, capelin, polar cod, amphipods and euphausiids are common components of their diet. The total breeding population is estimated to be 270,000 pairs, of which ca 90,000 pairs breed on Bjørnøya.
Black-legged kittiwakes are monitored on Bjørnøya and in western Spitsbergen. The size of several colonies is estimated annually in order to detect short- and long-term changes in population size. Moreover, to explain and even predict those changes, several other parameters are monitored such as the annual adult survival (Spitsbergen and Bjørnøya) and the average breeding success (Bjørnøya).
Places and areas
Fuglehuken is the next largest kittiwake colony in Svalbard, after Bjørnøya. Ossian Sarsfjellet is located in the innermost part of Kongsfjorden and is easily accessible from Ny-Ålesund.
Relations to other monitoring
- Monitoring programme
- International environmental agreements
- Voluntary international cooperation
- Related monitoring