Species › Birds

Caspian Tern

Sterna caspia

Order: Charadriiformes
Family: Laridae
Presence in the Strait: Seasonal
Abundance: scarce
Protection in Spain: Special protection (List)
In Spanish: Pagaza piquirroja

Marine taxonomy: validated in WoRMS, AphiaID 567825

Photograph: Jerry Gunner from Lincoln, UK, CC BY 2.0, vía Wikimedia Commons

Length: 47–54 cm
Wingspan: 130–145 cm
Weight: 575–675 g

Presence in the Strait

Scarce winter visitor to coasts and marshes (<15).

Identification

The largest of the Terns. Robust, with large distinctive red bill and grey upperparts. Summer plumage includes thick black crown and nape, with streaked forehead in winter. Juveniles have a more orange bill, paler legs and dark-flecked upperparts.

Movements

Prenuptial migration peaks in 2nd hf. April; two postnuptial peaks: 1st hf. September and 1st hf. October.

Ring recoveries

Finland (2) and Sweden (2).

Bioestrecho editorial text. Last revised: 8 September 2026.

Photographs from iNaturalist observations with the licence checked file by file. Those marked “Strait” were taken within the area; place and date are those of each observation.

Calendar in the Strait

18 %

Peak in September. Observations under CC0 or CC BY licences. The distribution also reflects observation effort.

Where it is seen

Open records from the atlas database, in cells of about 3.6 km. Opacity follows the square root of the count, and also reflects where people observe most.

See on the map

First open record: 26 October 1963
Latest record: 3 March 2025

The oldest and the most recent open observation in the extended area. A recent first observation does not mean the species is new: it means nobody had published it openly before.

Conservation

The catalogues, Andalusian and Spanish, are what binds; the Red Book assesses the Spanish population with IUCN criteria, and the global Red List is the context.

LCNTVUENCR

Andalusian Catalogue: Special protection (List)
Spanish Catalogue: Special protection (List)
Red Book of the Birds of Spain 2021: NE · Not evaluated · breeding
Global Red List (IUCN): LC · Least concern

Annex I of the Birds Directive

Andalusian Catalogue: Junta de Andalucía, list of 24 April 2025. Spanish Catalogue: MITECO, table of 30 June 2025. Red Book: SEO/BirdLife, 2021 (Annex I). IUCN: via GBIF, 6 September 2026. Red Book and IUCN categories are assessments; catalogue categories are legal obligations.

Phenology compared

Monthly distribution in proportion, by decade. It shows whether the passage is getting earlier or later.

1990–1999

2000–2009

2010–2026

Proportions, not totals: observation effort grew faster than any population.

Where they come from

4 birds ringed in other countries and recovered in the area.

Finland2
Sweden2

See the journey on the map

Same genus in the Strait

Sandwich Tern36–41 cm · Seasonal
Lesser Crested Tern35–37 cm · Migrant
Common Tern31–35 cm · Migrant
Roseate Tern33–38 cm · Vagrant
Forster´s Tern33–36 cm · Vagrant

Species of the same genus that also occur here, ordered by how close they are in size. Being relatives does not mean they are confused in the field, but that is where the doubts start: compare size and season.

Classification

Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Charadriiformes
Family: Laridae
GBIF taxon key: 2481236

Sources

Distribution and calendar: Bioestrecho's own database, ingested from GBIF and OBIS
Photograph: Jerry Gunner from Lincoln, UK, CC BY 2.0, vía Wikimedia Commons
Taxonomy: GBIF backbone, pending WoRMS for marine taxa
Editorial text: written by Bioestrecho
Last revised: 8 September 2026

Caspian Tern

Presence in the Strait

Identification

Movements

Ring recoveries

Gallery