Forster's Tern

Sterna forsteri

Introduction

Similar to Common Tern, but with a pale orange bill, Forster's Tern is a rare visitor from North America, with most records coming from around the Irish Sea during the winter months.

In some areas, the floating nests of Forster's Terns face an unusual hazard – spawning carp can work up such a frenzy that they sometimes dislodge eggs from the terns' nests.

Key Stats

Status

Very rare

Weight

160g

Seasonality

<1%

BTO Records

1.2k records

Population and distribution stats for:

No data

No current data

No current data

No data

No current data

% expansion

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.

IUCN Red List of Threatened Species (global)

Least Concern

Schedule 1 Licence required (to disturb)*

Birds Directive Annex 1

* 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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BOU Category

Source

First Record*

Cornwall, 1980

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

Population Change

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Population trends of this scarce species are not routinely monitored.

Distribution

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This species is a rare vagrant and was recorded during Bird Atlas 2007–11 as shown on the map.

Occupied 10-km squares in UK

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

No. occupied in winter

% occupied in winter

0.03%

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.

Breeding Distribution for Forster's Tern

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.

Distribution Change

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This vagrant is too rarely reported to map distribution change.

Seasonality

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Forster's Tern is a rare vagrant, recorded sporadically but most often in winter, and often involving returning individuals.

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 Forster's Tern 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

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.

Biology

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

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.

Classification, names and codes

Taxonomy, names and species codes for Forster's Tern

Classification and Codes

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Order: Charadriiformes
Family: Laridae
Scientific name: Sterna forsteri
Authority: Nuttall, 1834

BTO 2-letter code: FO
BTO 5-letter code: FORTE
Euring code number: 6180

Alternate species names

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Catalan: xatrac de Forster
Czech: rybák Forsteruv
Danish: Prærie-terne
Dutch: Forsters Stern
Estonian: sootiir
Finnish: hopeatiira
French: Sterne de Forster

German: Forsterseeschwalbe
Hungarian: tavi csér
Icelandic: Tálþerna
Irish: Geabhróg Forster
Italian: Sterna di Forster
Latvian: Forstera zirinš
Lithuanian: Forsterio žuvedra
Norwegian: Prærieterne

Polish: rybitwa czarnoucha
Portuguese: gaivina-de-forster
Slovak: rybár mociarny
Slovenian: ameriška recna cigra
Spanish: Charrán de Forster
Swedish: kärrtärna
Welsh: Môr-wennol Forster

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.