Larosterna inca (R.Lesson & Garnot, 1827)

Description

Size

The Inca tern measures roughly 39 to 42 cm (15 to 17 in) in length and weighs between 180 to 210 g (6.3 to 7.4 oz).

Adult Plumage

Its plumage has a unique coloration among terns. Adult Inca terns have a mostly dark slate-gray body, with paler underwing coverts and a slightly paler throat.

Distinctive Facial Markings

A white stripe extends backward from the base of the bill, fanning out into long, satiny feathers along the side of the neck that resemble a Salvador Dalí-style mustache.

Wing and Tail Features

The trailing edge of the wing, which includes the tips of the secondaries and the three inner primaries, is white. The tail is black, moderately forked, the iris is brown, and the legs and feet are dark red.

Bill Characteristics

The bill ranges from bright to dark red, with bare yellow skin at its base.

Juvenile Plumage

Newly hatched Inca tern chicks are purplish-brown, and molt into brownish-gray plumage before developing their full adult plumage. Chicks have dark, horn-colored bills and legs that gradually turn the red seen in adult birds.

Distribution and habitat

Core Breeding Range

The Inca tern lives in the Humboldt Current region. It breeds from Lobos de Tierra in northern Peru south to the Aconcagua River near Valparaíso, Chile.

Post-Breeding Dispersal

After breeding, some individuals disperse north into Ecuador and south to the Puerto Montt area of Chile, where multiple research-grade sightings with photos are documented on the biodiversity database iNaturalist, including a sighting of a group of four birds.

Vagrant Records

It is a casual visitor to Panama and Costa Rica, and has also been recorded as a vagrant in Guatemala and Hawaii. Documented Inca terns in Hawaii stayed in the Hawaiian archipelago from March through November.

Unconfirmed Colombia Records

The South American Classification Committee of the American Ornithological Society lists the Inca tern's presence in Colombia as "hypothetical", due to a number of unverified or undocumented sightings. One research-grade sighting with a photo has been documented on iNaturalist from the coast of Buenaventura, Colombia's Isla Cascajal, dated July 2023; however, the species' popularity in captivity complicates the assessment of this out-of-range record.

Nesting and Roosting Habitats

The Inca tern nests on sea cliffs, guano islands, manmade structures such as ledges under piers, and abandoned barges. It will gather with other sea and shorebirds on sandy beaches.