Royal Tern

How to find it

Head for river mouths in the Gulf of Nicoya and Golfo Dulce, where Royal Terns are easy to find. Scan floating logs offshore, since groups often sit there. Check mud and sand banks near estuaries and mangroves as well. Listen for the ka-rreet call, a good way to locate the tern before you see it. Royal Terns are often among the first birds a visitor sees at the seashore, alongside Laughing Gulls and Brown Pelicans.

How to recognise it

Start with the size: this is a large tern. Then check three things in order: the orange bill, the black legs and the forked tail.

In Costa Rica you will most often see non-breeding birds, which have black only on the back half of the crown. In winter plumage the forehead and front crown turn white, and only the rear crest and a stripe through the eye stay black.

Against the Caspian Tern, the only larger tern in the Americas, the Royal is slimmer, with a deeper orange bill and a longer forked tail.

What it sounds like

Recording: Linzy L., CC BY-SA 4.0, source, read 4 Nov 2026.

Behaviour and diet

The Royal Tern is usually seen alone, sometimes in small groups, and it may mix with Sandwich Terns. Hunting birds fly slowly along the coast and dive for small fish, which they grab with a quick strike of the bill. Between fishing bouts they rest in groups on logs floating in the sea. The species often feeds in small sheltered waters such as estuaries, mangroves and lagoons.

Where it lives

In Costa Rica this is a bird of the coast. It occurs on both the Pacific and Caribbean sides and is called fairly common all year on both. It can be locally abundant at river mouths, and it rests on floating logs offshore and on mud and sand banks near estuaries and mangroves. Offshore surveys have also found it off the north, central and southern Pacific coasts, so it is not tied only to the shoreline.

When to see it

A Costa Rican tour site calls it a migratory bird that spends the northern winter in the country. Some birds reach Costa Rican waters from Galápagos breeding colonies between late March and early May, and researchers have seen it off the Pacific coast in January, March, April, September and November.

Similar birds

The Caspian Tern has a heavy red-orange bill and large dark patches under the wings, while the Royal is slimmer with a deeper orange bill. The Elegant Tern is very similar but smaller, which shows only when the two are side by side, and it has a much slimmer bill that often looks slightly droopy. The Sandwich Tern is smaller and slimmer, with a slender black bill with a yellow tip.

Names and lore in Costa Rica

Besides the AOCR name Pagaza Real, Spanish sources also call this bird charrán real, gaviotín real and tirra canalera, and the names vary by country. The genus name Thalasseus comes from a Greek word for fisherman, and maximus means greatest, so the name works out as 'the greatest fisher'.

Status and conservation

The AOCR list marks the Royal Tern as M (migratory), yet it is fairly common all year on both coasts and Least Concern.

Photography tips

Floating logs are the best bet, because groups often sit on them, which makes them easy to spot from a boat or the shore. Wooden posts in the sea and mud and sand banks near estuaries are also worth scanning for resting birds.