Sternula lorata (Philippi & Landbeck, 1861)

Physical Description

The Peruvian tern, scientifically named Sternula lorata (Philippi & Landbeck, 1861), is a very small tern species with a body length of approximately 24 cm (9.4 in). The upper portions of its head and neck are black, while the rest of its head is white. Its back, wings, and tail are grey; its throat, chin, and breast are white; and its lower chest, belly, and flanks are pale grey.

Plumage and Soft Parts

The under tail-coverts are white. Its bill is yellow with a black tip, its irises are brown, and its legs are yellowish. The pale grey colour of its underparts distinguishes this species from other small terns.

Behavior and Vocalizations

It has a very rapid, distinctive wingbeat. Its vocalizations include a shrill "kik", a harsh "gree", and a descending series of "kee-ee-eer" notes.

Distribution Range

This species is endemic to the tropical west coast of South America. Its distribution ranges from northern and central Ecuador, through Peru, to northern Chile, extending as far south as the Mejillones Peninsula.

Population Status by Country

Its conservation and population status in Ecuador is unclear. In Peru, it has been confirmed at four sites, where it breeds at the back of beaches in association with wetlands.

Breeding Site Records

Nine known sites for the species exist in Chile, all near Mejillones, and Peruvian terns breed a short distance inland in the desert at all these locations. Additional unrecorded breeding sites may exist, and some previously recorded sites have not been revisited since they were first documented many years ago.

Diet Composition

Observed prey items in the Peruvian tern's diet include Peruvian anchoveta (Engraulis ringens), king gar (Scomberesox scombroides), Peruvian silverside (Odontesthes regia), and mote sculpin (Normanichthys crockeri).

Breeding Season

Breeding occurs between August and February, with most breeding activity concentrated between October and January. Nests are widely spaced within loose colonies that can hold up to twenty-five pairs.

Nesting Locations

Nests are typically located near coastal wetlands and lagoons, where the birds forage. Some individuals nest on beaches and dunes 100 to 200 metres inland from the high tide mark, while others nest one kilometre or more inland on sandy plains.

Reproductive Traits

Clutches contain one or two eggs, and both eggs and chicks have camouflage to avoid being detected by predators. After the breeding season, the birds leave the coast and may move out to open sea.

El Niño Response

During El Niño years, the terns are absent from the shore, do not attempt to breed, and most likely remain out at sea.