Large-billed TernPhaetusa simplexWhere and when to see them

The Large-billed Tern is a distinctive South American waterbird with an exceptionally long, thick yellow bill. It is widespread across much of tropical South America, including the Amazon Basin. Closely associated with large rivers, it feeds mainly on fish and often rests on exposed sandbars. Its bold wing pattern and powerful bill make it one of the more recognizable terns seen during an Amazon river cruise.

Size

Approximately 38–42 cm long.

Weight

Approximately 208–247 g.

Lifespan

Not well documented in the wild.

Status

Least Concern (IUCN).

Large-billed Terns patrol rivers in steady flight, scanning the water for fish. They capture prey by plunging into the water or taking fish near the surface. Birds may forage alone or in loose groups, especially where fish are concentrated. Away from feeding areas, they gather on sandbars and open riverbanks to rest and preen. Breeding often takes place in colonies on exposed sand or gravel, sometimes alongside other terns and skimmers. The nest is a shallow scrape in the ground rather than a constructed platform. Adults defend nesting areas with loud calls and aerial swoops at intruders.

• It is the only living species in the genus Phaetusa.
• Its oversized yellow bill is its most distinctive feature.
• Its nest is a simple scrape on an exposed river island or bank.
• Amazon river levels help determine where it can rest and breed.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

In the Amazon Basin, this species is most closely associated with broad rivers and their exposed sandbars. It also uses river islands, lakes, lagoons, and other open freshwater habitats. Bare sand and gravel provide important resting and nesting sites. Seasonal changes in river level strongly influence the availability of these sites. Although primarily an inland bird, it also occurs locally in estuaries and coastal waters.

Fish make up most of the Large-billed Tern's diet. It hunts visually over open water, diving or dipping to seize prey with its bill. It also occasionally takes insects and other small aquatic animals. Feeding locations shift with water conditions and prey availability.

Common name

Large-billed Tern

Scientific name

Phaetusa simplex

Animal group

Birds

Size

Approximately 38–42 cm long.

Weight

Approximately 208–247 g.

Lifespan

Not well documented in the wild.

Status

Least Concern (IUCN).

Identification

Look for a medium-large tern with a disproportionately long, heavy yellow bill and yellowish legs. Breeding adults have a black cap, pale gray upperparts, and white underparts. In flight, broad white areas on the wings contrast sharply with the black outer flight feathers. Outside breeding condition, the forehead becomes whiter, while immature birds may show mottled upperparts and a less brightly colored bill.