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Kongsfjorden Eider Breeding Population Has Remained Below 3,000 Pairs in Recent Years

Two common eiders flying over the coast
Conservation · Population & status

The breeding population of common eider (Somateria mollissima borealis) in Kongsfjorden, Norway, Svalbard, has shown a downward trend since around 2012 and has remained below 3,000 breeding pairs in recent years, according to the Norwegian Polar Institute’s monitoring update published on 7 May 2026.

The long-running series shows a change from earlier decades. Between 1981 and 1997, the number of nesting females in Kongsfjorden generally ranged between 3,000 and 4,000, and from 2000 to 2012 it varied between about 2,500 and 3,500. Because the monitoring is based on nesting females and nests, these counts are used as the measure of breeding pairs. Since 2012, the programme has recorded a gradual decline.

Every island is surveyed once each June

The breeding population is monitored by visiting all islands in Kongsfjorden once during June. Teams of two or three people count nesting females and eggs, covering the eggs with down before moving on. Females generally return to the nest within a few minutes after the count.

The total nest count also includes nests that have already been depredated by polar bears early in the season. This is important because predation can occur before the annual survey and would otherwise make the number of breeding attempts appear lower than it was.

Sea ice no longer explains the recent trend

In the 1980s and 1990s, the amount of sea ice in Kongsfjorden was an important influence on where and how many eiders could breed. In recent years the fjord has generally been ice-free during the relevant period, and the Norwegian Polar Institute states that other factors must now be contributing to the population trend.

Increased predation is one possibility discussed in the monitoring programme. Polar bears have visited breeding islands more frequently, and glaucous gulls can exploit disturbed colonies. In 2018, 2020 and 2022, more than 1,000 nests were recorded as having been depredated by polar bears and glaucous gulls. The monitoring programme also points to conditions in the wintering areas as another possible influence.

The Norwegian Polar Institute emphasises that the causes of the decline still need to be clarified. The current monitoring therefore documents a persistent downward trend rather than attributing it to a single demonstrated cause.

Common eiders are an important part of the Arctic marine food web because they feed heavily on benthic organisms. Changes in their breeding population can therefore also reflect broader changes in coastal Arctic ecosystems, making the long Kongsfjorden time series valuable for continued environmental monitoring.

Sources and image credit

  1. Norwegian Polar Institute. (2026). Breeding population of common eiders in Kongsfjorden, number of breeding pairs. Environmental Monitoring of Svalbard and Jan Mayen (MOSJ).Primary monitoring indicator, last updated 7 May 2026; documents the decline since around 2012, current level below 3,000 pairs, survey method and possible contributing factors.

Image: Marton Berntsen — two common eiders photographed in flight at Steinodden, Norway, 8 November 2016; representative image, not birds from the Kongsfjorden monitoring series. Source: Wikimedia Commons. · CC BY-SA 4.0 · Source

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