Last updated 2 March 2023

The common eider (Somateria mollissima borealis) is monitored due to that it is a significantly important species in the Arctic marine food chain. Eiders feed on benthic organisms and can therefore be an indicator for this part of the ecosystem. Significant declines in the population sizes of the four eider species; steller’s eider, king eider, common eider and spectacled eider have been recorded in many Arctic areas. On the mainland, common eider has the Red List Vulnerable (VU) status, while the Svalbard population has the Least Concern (LC) status. The eider population in the Kongsfjord has shown a downward trend since 2012.

Common eider
Photo: Stein Ø. Nilsen / Norwegian Polar Institute

What is being monitored?


Breeding population of Common eiders in Kongsfjorden

The number of breeding eiders on the islands in Kongsfjorden varies between years. Previously, the breeding population of eider has been determined by the ice situation in the Kongsfjord. In recent years there has been no ice on the Kongsfjord, and there are probably other factors affecting the eider population. In the period from 1981 until 1997, population of eider females in the Kongsfjord ranged between 3000-4000 individuals. From 2000 to 2012, the population varied between 2,500-3,500 individuals. In the Kongsfjord in Svalbard, since 2012 a decline in the nesting population has been recorded. Today’s breeding population (2022) of eider in the Kongsfjord is 2,169 individuals.
(Cite these data: Norwegian Polar Institute (2022). Breeding population of common eiders in Kongsfjorden, number of breeding pairs. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL: http://mosj.no/en/fauna/marine/common-eider.html)

Details on these data

Last updated2 March 2023
Update intervalYearly
Next updateFebruary 2024
Commissioning organizationMinistry of Climate and Environment
Executive organizationNorwegian Polar Institute
Contact personsGeir Wing Gabrielsen

Method

All islands are surveyed once in June each year. The survey is conducted by 2 or 3 persons. The eiders leave their nests when they are approached. The number of eggs are recorded and the eggs are covered with down. The female is back on the nest about 2–5 minutes after the count.

Because all nests are surveyed, there is a high degree of certainty of the number of nests per island. The same goes for the number of eggs.

Quality

National and international standards for surveys of eider nests are followed.

Other metadata

All data are entered into the Norwegian Polar Institute Colony database.

Status and trend

The present population of common eiders is estimated to be between 13,500 and 27,500 pairs.

Even without reliable population numbers from historical times, it is assumed that uncontrolled harvesting of eggs and down at the beginning of the 20th century affected the population negatively.

The harvesting resembled plundering, affecting the breeding success negatively. This and other potential anthropogenic factors contributed to the decision to give the species total protection in Svalbard in 1963. Further 15 bird sanctuaries were, furthermore, established in 1973, to secure important nesting areas for birds, especially common eiders and geese. Because of the special protection given to the species it is important to monitor it over time, and understand what affects it.

The population of common eiders in Kongsfjorden, including the Kongsfjorden and Blomstrandhalvøya bird sanctuaries, has been monitored by the Norwegian Polar Institute since 1981.

Common eider population development can be affected by climate. In the Arctic, the climate is changing rapidly, with both higher temperatures and less ice and snow cover. This may affect the physical conditions for breeding, including the timing of snow and ice melt on the islands and changes in the marine environment affecting the availability of prey.

Causal factors

The climate has changed in the last 10–15 years of the monitoring period in Kongsfjorden. This includes higher air and ocean temperatures, a decrease in sea ice and earlier snow and ice melt in the spring (Vihtakari et al. 2018).

In the Arctic, the climate is rapidly changing, with increases in air and sea temperatures as well as reduced ice and snow cover. This can affect the physical conditions for nesting. The time period when the islets are free of ice and snow changes, and the eider can start breeding earlier. The sea temperature is higher, which can affect food availability for eider. In recent years, the Kongsfjord has also received more and more visits from polar bears who come to the islets in the summer (Prop et al. 2015).

In the 1980s and 90s the breeding population of eider were highest in years with little ice in the Kongsfjord. Both in 2013 and in 2016 we had a low number of eiders that nested in the Kongsfjord (1941 and 1901 nesting eider respectively). From 2012 to 2022, the breeding population of eider females in Kongsfjorden has been reduced from 3533 to 2169 individuals. This is a reduction of 39%.This change cannot be explained by the ice situation, as the Kongsfjord has been ice-free during the breeding season since 1999. Studies of the eider females’ migration, using light loggers, show that two-thirds of the eider females from the Kongsfjord overwinter in Iceland, while approximately one-third overwinter on the coast of northern Norway (Hanssen et al. 2016). Studies carried out show that eider females overwintering in Iceland are affected by climate conditions in the winter area (measured using the North Atlantic Oscillation (NAO index) (Guery et al. 2017). Changes in the ocean temperature in this area probably affect the access to food sources in the winter area, such as reduced food availability or access to food of lower quality. For eider females overwintering in Iceland, this may result in their dying in the winter area as a result of poor access to nutrition/food, or that they arrive at the breeding area on Svalbard in poor condition and that they therefore will not nest. Another reason for the decline of eiders in the Kongsfjord may be the increased predation from polar bears and polar gulls. Due to the lack of good nutritional conditions in the north of Svalbard several polar bears (with and without cubs) have been moving from the north of Svalbard to the Kongsfjorden to eat eggs from eiders and white-cheeked geese. The polar gulls follow the polar bears in the Kongsfjord and when the eider females leave the nest, the eggs become available to both the polar bears and the polar gulls, which contribute to the loss of many eggs. In 2022, when the counts were made around 20-25 June, there were 1129 active nests while 1040 nests were predated.

Consequences

The eider population in the Kongsfjord has shown a downward trend between 2012 and 2020. In the coming years, it is important to clarify the causes of this decline. A consequence of the downward trend will be a reduced grazing of the eider’s food organisms, especially on the west side og Svalbard, where most of the eiders are nesting.

About the monitoring

Previously, the breeding population of eider has been determined by the ice situation in the Kongsfjord. In recent years there has been no ice on the Kongsfjord, and there are probably other factors affecting the eider population. Future studies will be able to provide information about this. Is it the overwintering area that has become worse for eider females or is it the increased predation that contributes to the decline of eiders in the Kongsfjord?

Eiders are monitored as the species might be a good indicator to study the effects of climate change in the Arctic.

The Arctic Council working group Conservation of Arctic Flora and Fauna (CAFF) has selected the eider species as one of several groups of Arctic birds that should be monitored. To restore, stabilize and manage the eider populations in a sustainable manner, CAFF has prepared circumpolar monitoring and action plans for these species. It is a national responsibility to follow up this work in Svalbard.

Relations to other monitoring

Monitoring programme

  • None

International environmental agreements

  • None

Voluntary international cooperation

  • None

Related monitoring

  • None

Further reading

Publications

  1. Chaulk, K.G., Mahoney, M.L. 2012. Does spring ice cover influence nest initiation date and clutch size in common eiders? Polar Biology 35(5): 645–653. DOI:10.1007/s00300-011-1110-2
  2. Guery, L., Descampes, S., Pradel, R., Hanssen, S.A., Erikstad, K.E., Gabrielsen, G.W., Gilchrist, G.G. & J. Bety. 2017. Hidden survival hetrogeneity of three Common eider populations in response to climate fluctuations. Journal of Animal Ecology, doi : 10.1111/1365-2656.12643.
  3. Hanssen, S.A., Gabrielsen, G.W., Bustnes, J.O., Bråthen, V.S., Skottene, E., Fenstad, A.A., Strøm, H., Bakken, V., Phillips, R.A., Moe, B. 2016. Migration strategies of common eiders from Svalbard: implications for bilateral conservation management. Polar Biology 39: 2179–2188. DOI:10.1007/s00300-016-1908-z
  4. Kovacs, K.M., Lydersen, C. (eds.) 2006. Svalbards fugler og pattedyr. Tromsø: Norwegian Polar Institute.
  5. Mehlum, F. 2012. Effects of sea ice on breeding numbers and clutz size of a high arctic population of common eider Somateria mollissima. Polar Science: 143–153.
  6. Moe, B., Stempniewicz, L., Jakubas, D., Angelier, F., Chastel, O., Dinessen, F., Gabrielsen, G.W., Hanssen, F., Karnovsky, N.J., Ronning, B., Welcker, J., Wojczulanis-Jakubas, K., Bech, C. 2009. Climate change and phenological responses of two seabird species breeding in the high-Arctic. Marine Ecology Progress Series 393: 235–246. DOI:10.3354/meps08222
  7. Moe, B., Hanssen, S.A., Bårdsen, B.-J., Bourgeon, S., Hanssen, F., Pavlova, O., Nielsen, C.P., Gerland, S., Gabrielsen, G.W. 2012. Effekter av predatorkontroll og klima på bestandsforhold hos ærfugl på Svalbard. Sluttrapport for Svalbards Miljøvernfond. NINA Rapport 868. Tromsø: Norwegian Institute for Nature Research. 30 pp.
  8. Prop, J., Aars, J., Bårdsen, B.J., Hanssen, S.A., Bech, C., Bourgeon, S., Fouw, J.d., Gabrielsen, G.W., Lang, J., Noreen, E., Oudman, T., Sittler, B., Stempniewicz, L., Tombre, I., Wolters, E., Moe, B. 2015. Climate change and the increasing impact of polar bears on bird populations. Frontiers in Ecology and Evolution 3: 00033. 12 pp. DOI:10.3389/fevo.2015.00033
  9. Serreze, M.C., Holland, M.M., Stroeve, J. 2007. Perspectives on the Arctic’s Shrinking Sea-Ice Cover. Science 315: 1533–1536.
  10. Strøm, H. 2006. Ærfugl. Pp. 104–108 in: Kovacs, K.M., Lydersen, C. (eds.): Svalbards fugler og pattedyr. Tromsø: Norwegian Polar Institute.
  11. Vihtakari, M., Welcker, J., Moe, B., Chastel, O., Tartu, S., Hop, H., Bech, C., Descamps, S., Gabrielsen, G.W. 2018. Black-legged kittiwakes as messengers of Atlantification in the Arctic. Scientific Reports 8: 1178. 11 pp. DOI:10.1038/s41598-017-19118-8