Royal Tern (Thalasseus maximus)

OTHER NAMES: N/A
Latin Etymology: Thalasseus ("fisherman") maximus ("greatest")

Two non-breeding Royal Tern (Thalasseus maximus) at Tarcoles, Costa Rica - November 2025

Featured Subspecies: N/A
Weight: 350-500g  /  Length: 45-50cm  /  Wingspan: 130cm
NO UK STATUS/ IUCN Red List: Least Concern

The joint second largest of all terns, second only to the Caspian, the Royal Tern is a large sturdy bird with a distinct orange beak that would differentiate it from other large terns within it's range. They are an exclusively coastal species, found around the Carribean and Baja Califoria, as well as the South East of South America year round, as well as Central America in the Winter.

Related Species:
Order: Charadriiformes

Family: Laridae (Formerly Sternidae)

Genus: Thalasseus

SUBSPECIES: none - monotypic 

 - Sighting Locations -

COSTA RICA - Spanish - Charrán Real
Wintering migrant
 - COSTA RICA 2025 TRIP: Seen at Tarcoles

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto

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Elegant Tern (Thalasseus elegans)

OTHER NAMES: N/A
Latin Etymology: Thalasseus elegans

Non-breeding Elegant Tern (Thalasseus elegans) at Monterey, California - September 2022

Featured Subspecies: N/A
Weight: 200-300g  /  Length: 39-43cm  /  Wingspan: 76-81cm
NO UK STATUS / IUCN Red List: Near Threatened

A somewhat paradoxical species - they have incredibly dense breeding colonies but only in a few very specific locations around the Gulf of California, but meanwhile its non-breeding range stretches from central Chile up along the Pacific Coast to the Oregon. They also, from a birding perspective are unusually variable in their non-breeding plumage, with their bills in particular ranging across red, orange, yellow and pink, making it a somewhat frustrating exercise to pick out other species in amongst them.

Related Species:

Order: Charadriiformes

Family: Laridae (Formerly Sternidae)

Genus: Thalasseus

SUBSPECIES: none - monotypic 

 - Sighting Locations -

UNITED STATES 
Breeds at a single site in California, nn-breeding along Souther Half of West Coast
 - CALIFORNIA 2022 TRIP: Seen at Hayward and Monterey 

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto

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Sandwich Tern (Thalasseus sandvicensis)

OTHER NAMES: Boatswain, Surf Tern
Latin Etymology: Thalasseus ("fisherman") sandvicensis (named for Sandwich, Kent)

Assorted age and gender Sandwich Terns (subspecies T. s. sandvicensis) at Farne Islands, Northumbria - July 2009

Featured Subspecies: Thalasseus sandvicensis sandvicensis OR monotypic
Weight: 180-300g  /  Length: 34-45cm  /  Wingspan: 100cm

UK AMBER LIST / IUCN Red List: Least Concern

The Sandwich Tern is an exclusively coastal tern which breeds primarily along the East and South Coasts during the Summer although it may be seen on passage elsewhere. It is technically our second most common tern after the Arctic, but, both of the above I would consider harder to see on the basis that they are purely coastal dwelling rather than the common tern which breeds inland. Terns are easiest to photograph when on the ground and I would recommend going to the Farne Islands in the breeding season for this species.

Related Species:

Order: Charadriiformes

Family: Laridae (Formerly Sternidae)

Genus: Thalasseus
Subspecies: Either T. s. sandvicensis, T. s. acuflavidus, T. s. eurygnathus or monotypic*

- Sighting Locations -

UNITED KINGDOM - Local Summer breeding migrant (12,000 pairs)

 - Birds seen commonly at a large number of sites, including but not limited to Trevose Head, Rye Harbour, Oare Marshes and Farne Islands

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto 

*The American subspecies acuflavidus and eurygnathus are split as Cabot's Tern and Cayenne Tern, either as one or two species, which I will treat as separate should I see them, but I mention them here for clarity. 

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