Sandwich Tern

How to find it

Look for it on ocean shores and in estuaries, where it hunts small schooling fish. Scan coastal waters and river mouths rather than inland sites. Go through resting tern flocks bird by bird, looking for one bigger than a Common Tern but daintier than a Royal Tern. Then check for a ragged crest and a black bill with a yellow tip. Royal Terns sometimes gather with Sandwich Terns, so do not stop at the biggest birds.

How to recognise it

Learn one feature and the rest follows.

The Sandwich Tern is the only crested tern with a black bill. The tip of that bill is yellow, which separates it from other crested terns.

Look for a ragged crest on a bird bigger than a Common Tern but daintier than a Royal Tern. It is smaller and slimmer than the Royal Tern, so size helps as well as bill colour.

In non-breeding plumage the crown is mottled black and white, or nearly all white. The bill stays black with a yellow tip. The legs are black, except in one South American and Caribbean subspecies, where they can be partly yellow.

What it sounds like

Recording: Yves Bas, CC BY 4.0, source, read 4 Nov 2026.

Behaviour and diet

It eats mostly small fish, which it catches by plunge-diving, so a tern dropping into the water is worth a closer look. It is very social and breeds in dense colonies, although that happens elsewhere and not in Costa Rica.

Around its nest it is fairly mild mannered. Unlike Common Terns, which dive-bomb people who come close, it is not quick to attack, and it often nests among Common Terns.

Where it lives

Birds wintering in the Americas use sand beaches, sandbars, reefs and barrier islands. They also use the Panama Canal and short stretches of rivers that flow into salt water. That description is range-wide and comes from Cabot's Tern, which the AOCR lumps with this species.

It is rarely seen inland or far out at sea, so think of coasts, estuaries and river mouths. In Costa Rica, the records we have are from the Gulf of Nicoya, at shrimp farms with shallow lagoons and at a salt farm.

When to see it

A Costa Rican trip report from a September 19 outing around the Gulf of Nicoya lists the species at Chomes and Cocorocas.

Similar birds

The Royal Tern is large with an orange bill and sometimes gathers with Sandwich Terns. Elegant Tern and Lesser Crested Tern usually have orange bills, while the Sandwich Tern has a black bill with a yellow tip. The Cayenne Tern, a subspecies from the southern Caribbean and Atlantic South America, has an all-yellow or pale-orange bill and lacks the black bill with a yellow tip.

Names and lore in Costa Rica

Costa Rican sources use Pagaza Puntiamarilla as the Spanish name for the Sandwich Tern, including a town bird list for Turrialba. The same list gives Pagaza Real for the Royal Tern and Pagaza Elegante for the Elegant Tern.

Status and conservation

The Costa Rican checklist (AOCR), updated June 2026 and now at 944 species, marks the Sandwich Tern as M, a migrant, so it is a visitor and does not breed in the country.

Photography tips

The Chomes shrimp farm lagoons hold the most birds when the tide is low, so plan a visit then. The report lists Sandwich Tern here alongside Royal Tern and Black Skimmer, so you can compare bill colour and size side by side.