Eider

Somateria mollissima

Introduction

This seaduck breeds around the coasts of northern Britain & Ireland, but can be seen further south during the winter months.

British and Irish breeding Eider are at the southern edge of a wider breeding range; while birds breeding further north are migratory, moving thousands of kilometres, our individuals make relatively short movements outside of the breeding season.

Eider feed on Blue Mussels and other molluscs, together with crustaceans and echinoderms. These are taken during dives, typically down to 3 m or so. Individuals favour sheltered feeding and resting sites during the winter, reducing their exposure to the elements.

Key Stats

Common

2.1kg

4-6

BTO Records

270k records

Publications

Population and distribution stats for:

No data

37k Pairs

5.1% expansion

No data

86k

-0.9% contraction

Identification

Curated resources to aid in the identification of Eider

Songs and Calls

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Listen to example recordings of the main vocalisations of Eider, provided by xeno-canto contributors.

Song:

Call:

Status and Trends

Population size, trends and patterns of distribution based on BTO and partnership surveys and atlasses with data collected by BTO volunteers.

Conservation Status

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This species can be found on the following statutory and conservation listings and schedules.

UK Birds of Conservation Concern

Amber listed

Species of European Conservation Concern

Endangered

IUCN Red List of Threatened Species (global)

Near Threatened

Schedule 1 Licence required (to disturb)*

Birds Directive Annex 1

Listed on the Annexes of*

WBD(II*,III*), Bern(III), Bonn(II), AEWA

* A guide only. Check details with the original legislation, especially those marked with an asterisk. See About Birdfacts for more information.

Population Size

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UK (breeding)

37 Pairs (2012-15)

Source

UK (winter)

86 thousand (2011-15)

Source

BOU Category

Source

First Record*

Recorded in Anglo-Saxon times

* First documented occurrence. Most species undoubtedly occurred before this. See About Birdfacts for more information.

Population Change

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The extent of breeding range of the Eider is relatively unchanged since the 1968–72 Breeding Atlas, with gains in occupied 10-km squares Wales, Morecambe Bay and the Isle of Man but some losses in western Scotland and Shetland (Balmer et al. 2013). In Shetland, where the birds are believed to be from the faeroensis subspecies, the has been a strong decline from 17,000 individuals in 1977 to 4,627 in 2012 (Heubeck & Mellor 2013). The population trend elsewhere in the UK is unclear.

Distribution

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In winter Eiders are found all around the coastline of Britain with the exception of much of the Solway Firth, Cardigan Bay and the Bristol Channel. The greatest concentrations are along the North Sea coast from Shetland to North Yorkshire, and in the northwest in Argyllshire and the Clyde estuary, northern parts of Ireland and Morecambe Bay.

Occupied 10-km squares in UK

These figures come from Bird Atlas 2007 and indicate how widespread a species is.

No. occupied in breeding season

500

% occupied in breeding season

17%

No. occupied in winter

685

% occupied in winter

23%

Bird Atlas distribution maps show where bird species breed or winter in Britain and Ireland. For breeding maps, larger dots indicate higher certainty the species bred in that area.

Click the map to enlarge,
or view it on Bird Atlas Mapstore.

Click the map to enlarge,
or view it on Bird Atlas Mapstore.

To view and download up-to-date distribution information aggregated from across BTO and partnership surveys and schemes, see our data holdings on the NBN Atlas.

European Distribution Map

European Breeding Bird Atlas 2

Distribution Change

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Since the 1968–72 Breeding Atlas there have been notable breeding distribution gains in northwest Wales, Morecambe Bay, the Isle of Man, and throughout the north coast of Ireland.

Change in occupied 10-km squares in the UK

These figures come from Bird Atlas 2007-11 and indicate by how much occupied areas have expanded or contracted over recent decades.

% change in range in breeding season (1968–72 to 2008–11)

5.1 %

% change in range in winter (1981–84 to 2007–11)

-0.9 %

Bird Atlas distribution change maps show how bird distributions have changed through time. Coloured upward-pointing triangles show places apparently colonised over the period; grey downward-pointing triangles show places apparently vacated. Shading show places occupied.

Click the map to enlarge,
or view it on Bird Atlas Mapstore.

Click the map to enlarge,
or view it on Bird Atlas Mapstore.

Seasonality

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Eiders are present throughout the year at suitable coastal locations.

Weekly pattern of occurrence

The graph shows when the species is present in the UK, with taller bars indicating a higher likelihood of encountering the species in appropriate regions and habitats.

Phenology graph — Weekly occurrence patterns (shaded cells and reporting rates (vertical bars) based on BirdTrack data. Reporting rates give the likelihood of encountering the species each week.

Movement

Information about Eider movements and migration based on online bird portals (e.g. BirdTrack), Ringing schemes and tracking studies.

Britain & Ireland movement

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View a summary of recoveries in the Online Ringing Report

Foreign locations of birds ringed or recovered in Britain & Ireland

Dots show the foreign destinations of birds ringed in Britain & Ireland, and the origins of birds ringed overseas that were subsequently recaptured, resighted or found dead in Britain & Ireland. Dot colours indicate the time of year that the species was present at the location.

Winter (Nov-Feb)
Spring (Mar-Apr)
Summer (May-Jul)
Autumn (Aug-Oct)

Foreign locations of birds ringed or recovered in Britain & Ireland

European movements

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EuroBirdPortal uses birdwatcher's records, such as those logged in BirdTrack to map the flows of birds as they arrive and depart Europe. See maps for this species here.

The Eurasian-African Migration Atlas shows movements of individual birds ringed or recovered in Europe. See maps for this species here.

Biology

Lifecycle and body size information for Eider, including statistics on nesting, eggs and lifespan based on BTO ringing and nest recording data.

Productivity and Nesting

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Nesting timing

Typical (exceptional) number of broods

Source

Egg measurements

Typical length x width

77x52 mm

Mass (% shell)

110g (8%)

Source

Clutch Size

Typical number

6-4 eggs

Observed minimum and maximum

1-8 eggs

Source

Incubation

Incubation by

Female

Typical duration

28-25 days

Source

Fledging

Type of chick

Precocial, downy

Typical duration

75-65 days

Source

Survival and Longevity

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Survival is shown as the proportion of birds surviving from one year to the next and is derived from bird ringing data. It can also be used to estimate how long birds typically live.

View number ringed each year in the Online Ringing Report.

lifespan

Typical life expectancy of bird reaching breeding age

14 years with breeding typically at 3 years

Source

Maximum age from a ringed bird

35 years, 6 months, 26 days (set in 1994)

Source

Survival of adults

All adults

0.916±0.017

Source

Survival of juveniles

All juveniles

0.33±0.06 (in first year)

Source

Biometrics

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Wing length and body weights are from live birds (source).

Wing length

Average ±1 std deviation; range and sample size in brackets.

All adults

290.2±14.9 mm

(267-312 mm, N=62)

Female

284±13.8 mm

(255.5-298.5 mm, N=40)

Male

301.4±9.1 mm

(287-313 mm, N=22)

Body weight

Average ±1 std deviation; range and sample size in brackets.

All adults

290.2±14.9 mm

(267-312 mm, N=62)

Female

284±13.8 mm

(255.5-298.5 mm, N=40)

Male

301.4±9.1 mm

(287-313 mm, N=22)

Ring Size

Classification, names and codes

Taxonomy, names and species codes for Eider

Classification and Codes

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Order: Anseriformes
Family: Anatidae
Scientific name: Somateria mollissima
Authority: Linnaeus, 1758

BTO 2-letter code: E.
BTO 5-letter code: EIDER
Euring code number: 2060

Alternate species names

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Catalan: èider comú
Czech: kajka morská
Danish: Ederfugl
Dutch: Eider
Estonian: hahk
Finnish: haahka
French: Eider à duvet
Gaelic: Colc

German: Eiderente
Hungarian: pehelyréce
Icelandic: Æðarfugl
Irish: Éadar
Italian: Edredone
Latvian: liela pukpile, gaga
Lithuanian: paprastoji gaga
Norwegian: Ærfugl

Polish: edredon (zwyczajny)
Portuguese: êider
Slovak: kajka morská
Slovenian: gaga
Spanish: Éider común
Swedish: ejder
Welsh: Hwyaden Fwythblu

English folkname(s): St Cuthbert's Duck

Research

Interpretation and scientific publications about Eider from BTO scientists.

Causes of Change and Solutions

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Causes of change

The decline of the Shetland population (faeroensis) has been attributed initially to an oil pollution incident in 1978/79 and high levels of unexplained mortality the following winter; the causes of more recent declines are unknown but may include deterrence measures at aquaculture sites and predation by marine mammals including Killer Whales (Heubeck & Mellor 2013). A study in Northumberland identified changes to adult survival as the main driver of population changes, and suggested that this change was caused by food shortages and had led to recent more widespread declines across northern Europe (Coulson 2010). The same study identified very low survival of ducklings and, although this was not identified as the main driver of population change, the author suggested that increasing duckling survival might be the most likely means to reverse the trend for this species.

Publications (1)

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Eider population biology - the Forvie contribution

01.01.98

Papers

More Evidence

More evidence from Conservation Evidence.com

Partners

Birdfacts is based on data collected by volunteers participating in surveys that are organised and funded by BTO, RSPB, Esmée Fairbairn Foundation, JNCC and other partners.

BTO

Esmée Fairbairn Foundation

JNCC

RSPB

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