Inca Tern

This is a remarkably distinctive and elegant seabird characterized by its unique plumage and striking facial ornamentation, which make it stand out among other members of its family.

This is a medium-sized bird, measuring approximately 15 to 16.5 inches (39 to 42 centimeters) in length and weighing between 180 and 210 grams. The body plumage is a uniform, deep slate-gray, which contrasts beautifully with the white trailing edges of its wings, highly visible during flight. Its most defining physical attribute is the pair of long, white, curled mustached plumes extending from the gape below the eyes, framed by vibrant bright yellow wattles at the base of the bill. The robust, pointed bill and the webbed feet are a brilliant crimson red. Immature individuals are duller, possessing brownish-gray plumage, lacking the white facial plumes, and showing dark bills that transition to red as they mature.

Geographical distribution: This species is endemic to the west coast of South America, closely tied to the cold waters of the Humboldt Current. Its range spans from northern Peru (specifically around Lobos de Tierra Island) southward along the coast to central Chile, occasionally reaching as far south as the Los Lagos region. Vagrant individuals are occasionally reported along the southern coast of Ecuador.

Habitat: It is restricted to marine coastal and neritic environments. It is commonly found on rugged rocky cliffs, sea caves, offshore guano islands, and steep coastal headlands. The species relies heavily on cold, nutrient-rich upwelling zones, avoiding warmer oceanic waters far from the continental shelf.

Feeding: Its diet is highly specialized and primarily piscivorous, relying heavily on the Peruvian anchovy (Engraulis ringens). It also opportunistically consumes other small pelagic fish, planktonic crustaceans, and fish offal. To capture prey, it employs an agile plunge-diving technique, hovering briefly before dipping onto or just beneath the water surface. It frequently feeds in large, multispecies flocks, often associating with marine mammals such as South American sea lions (Otaria flavescens) and various cetaceans, which drive schools of fish toward the surface.

Behavior: It is highly gregarious, nesting and roosting in dense colonies that can number in the thousands. Known for its superb and acrobatic aerial maneuvers, it spends a significant amount of time on the wing. It is an extremely vocal species, producing a characteristic, high-pitched call that resembles a kitten´s mew, which is utilized for individual recognition and territory defense within the crowded colonies.

Nesting: Breeding occurs twice a year, mainly from April to July and again from October to December. Rather than building an exposed nest, it selects deep rocky crevices, caves, hollows, or abandoned burrows of the Humboldt penguin (Spheniscus humboldti) on steep coastal cliffs. The female typically lays one or two eggs which are pale buff or greenish with dark speckles. Both parents share incubation duties for 21 to 23 days and cooperatively feed the chicks with whole fresh fish until they fledge at about four weeks of age.

Conservation status: It is currently listed as Near Threatened (NT) on the IUCN Red List. The primary threats to its population include commercial overfishing of the Peruvian anchovy, the catastrophic impacts of El Niño-Southern Oscillation (ENSO) events which disrupt food availability, disturbance from guano harvesting operations, and predation by introduced feral cats and rats on breeding islands.