Black Skimmer

How to find it

Costa Rica gets both northern-winter and austral-winter skimmers, so check flocks in either half of the year. Look for resting birds on mud or sand banks, where they sit among gulls and terns. A boat trip on the Río Tárcoles mangroves is a good place to try, and a Carara-area itinerary notes that skimmers patrol the shallows there. The same boat trip also brings crocodiles and Boat-billed Herons. Late in the day is worth trying, since they feed mostly then.

How to recognise it

Start with the bill. It is blackish with a scarlet base, and the lower half is much longer than the upper half. The legs are red-orange. The eyes have vertical, cat-like pupils, which is unusual for a bird.

The rest of the bird is a big, long-winged tern shape with a black back.

Winter adults have a white forehead, face and hindneck, with a dark cap. Juveniles look scaly or mottled above because the feathers have pale buff edges.

Northern birds have white underwings and outer tail feathers. In southern birds these are dusky gray, which helps tell the two groups apart.

What it sounds like

Recording: Guy Babineau, CC BY 4.0, source, read 4 Nov 2026.

Behaviour and diet

Skimmers are social. By day they rest on mud or sand banks, usually with flocks of gulls and terns.

They feed at any hour, but mostly late in the day and at night when fish rise to the surface. A skimmer flies low with its bill open, and the long lower half cuts the water. When it touches a fish, the bill snaps shut. Because it feeds by touch, it can even hunt at night.

Flocks in flight may turn together in unison, with their long wings beating in step.

Where it lives

In Costa Rica it uses calm water: rivers, estuaries, lagoons, salt ponds, tidal flats, salt works and coastal lagoons. The wintering centre is the Gulf of Nicoya.

Smaller numbers turn up occasionally in the Tempisque basin, Bahía Salinas, a lake in the country and Golfo Dulce.

Across Central America the species is almost entirely coastal. It prefers open sand, gravel or shell bars, and it nests in colonies near terns.

When to see it

Birds that breed in North America pass through from mid September to late October and again from early April to late May, and they winter around the Gulf of Nicoya. A few South American breeders spend May to October around the Gulf of Nicoya and Golfo Dulce.

Similar birds

Field guides list Caspian, Royal and Common Terns as look-alikes. The skimmer is set apart by its black back, red-based bill with a longer lower half, and its low, bill-in-water feeding flight. Royal Tern often shares the same roosts, but it has a long orange bill and gray wings, and its call is a loud, rolling note, unlike the skimmer's bark.

Names and lore in Costa Rica

Rayador Negro is the Costa Rican Spanish name. Other Spanish names used across the range include Pico de Tijera, Picotijera Americano, Rayador de Agua and Rayadora.

Status and conservation

The official Costa Rican bird list gives this species the status M, meaning a migrant, under the name Rayador Negro.

Photography tips

At the Chomes shrimp pools, birds gather in the shallower inner pools once the water drops. Skimmers arrived from the beach in the morning, so go when the water is low.