Arctic Tern

How to find it

Plan on boat trips at sea, not beaches. Beginning birders should expect to find it mainly on open water, well offshore.

Still, a few birds have come near land. In October 2022 local birders documented a few feeding close to shore in the Playa Hermosa area, which hints it may come near shore more often than expected.

For terns in the Gulf of Nicoya, a Costa Rican guide advises going at high tide. At low tide the birds scatter across huge mud flats, while at high tide they move to salt ponds and shrimp ponds such as Chomes.

Look closely at every tern, since Common Tern looks very much alike.

How to recognise it

In breeding plumage the Arctic Tern is grey and white with a blood-red bill and feet. It has a black cap and nape, white cheeks and a deeply forked tail.

In winter plumage the forehead turns partly white, and the bill and legs turn black. This is the look to expect in Costa Rica, since the birds pass through outside the breeding season.

Juveniles also have a partly white forehead. Their grey mantle feathers have narrow, pale orange-brown edges.

It is a medium-sized tern, about 33 to 36 cm long, with a wingspan of 76 to 85 cm.

On a young bird, a middle toe longer than the lower leg separates a first-year Arctic from a similar young Common Tern. A close look at a young bird in Nicaragua also showed a short, delicate black bill and a small head, which give a Black Tern look.

What it sounds like

Recording: Richard Littauer, CC BY 4.0, source, read 4 Nov 2026.

Behaviour and diet

The Arctic Tern eats small fish and small marine crustaceans, which it catches by diving from the air into the water surface.

Tracking of Pacific birds showed they feed only by day and spend nights resting out of the water or flying. On the way south they also feed heavily at rich upwelling stopover areas.

A Costa Rican birder's blog describes a first-year bird found on a boat outing, weak on the water and probably hurt by strong storms days earlier.

Where it lives

Outside the breeding season the Arctic Tern is mostly found far out at sea. It is rarely seen in coastal bays and estuaries, and it migrates mainly well offshore.

In Costa Rica it is usually a bird of open ocean. Published reports come from various offshore places, including Cocos Island. A marine-bird study of the Pacific coast saw it more often well out at sea than inside the Gulf of Nicoya, and its authors think it uses more than one route through Costa Rican waters.

When to see it

Reported Costa Rican sightings fall in migration periods, late August to November and April to early June. A marine-bird study says most Central American records are from April and May, and in 2026 pelagic trips recorded a new national high count of four birds on 14 June.

Similar birds

Common Tern and Roseate Tern are the species most easily confused with it, and the Arctic and Common Terns share many informal common names. Compared with Common Tern, the Arctic has a longer tail and a bill of one colour. Roseate is slightly paler and has shorter wings.

Names and lore in Costa Rica

The official Spanish name in Costa Rica is Charrán Viajero. Elsewhere in Spanish it is also called Charrán Ártico or Gaviotín Ártico.

Status and conservation

The official list marks it as a migrant, and the IUCN lists it as Least Concern worldwide.