Red-legged cormorant

Phalacrocorax gaimardi is a cormorant of the family Phalacrocoracidae, described by Lesson and Garnot in 1828 ^[1]. It is endemic to South America: it lives on the Pacific coast from northern Peru, at Isla Foca, to southern Chile, and on the Atlantic only in Santa Cruz province, Argentina ^[2]. In Peru it is known as «chuita» or «cormorán de pata roja» ^[3], and the official list of threatened wildlife classes it as Endangered ^[4]. A 2025 paper places it in the genus Poikilocarbo ^[5].

In Peru it has been recorded along the coast, between Isla Foca, in Piura, and Playa Meza, in Tacna ^[3]. It occupies many rocky islands, islets and cliffs, both inside and outside the Reserva Nacional Sistema de Islas, Islotes y Puntas Guaneras ^[5].

In Chile, the 1998 to 2000 surveys found breeding sites from Arica (18°30′ S) to the Taitao peninsula (46°25′ S), with 40 breeding areas and at least 54 colonies ^[6]. There it nested only on high cliffs, sea caves or rocky islets near the shore, since it needs rock walls to breed; the median colony held 15 nests in Chile, against 5 in Peru and 30 in Argentina ^[6]. On the Atlantic coast, about 1100 pairs were counted in 13 colonies between 1992 and 1994, all in Santa Cruz, from 47°05′ S south to 50°23′ S ^[7].

It builds its nest on near-vertical rock walls, under overhangs, in places that can only be reached on the wing; at one Argentine colony the nests were 20 m above the sea ^[8]. When leaving the nest it gives a clear, warbling whistle, and pairs strengthen their bond by twining necks and preening each other ^[8].

The nest is made of seaweed, feathers and guano, and in Chile plastic litter was often found among the materials ^[6]. Breeding is highly asynchronous within and between colonies, and most breeding adults stay at the colonies all year round ^[6].

At Puerto Deseado, Argentina, in the 1998-1999 season, clutches held 2 to 4 eggs, with a mean of 3.04; eggs averaged 60.3 by 37.1 mm and weighed 47.1 g, and incubation lasted 34 to 38 days ^[9]. That season only 8 % of eggs produced a fledgling: of 75 chicks 64 died, and 21 of them fell into the sea after strong winds; gulls preyed on some of the eggs ^[9].

It has been described as an inshore fisher that stays within 3 km of the colony and hunts bottom fish and invertebrates in water less than 15 m deep ^[6]. More recent work on the Atlantic, however, indicates that it eats almost only pelagic prey; its diet includes the fish Sprattus fuegensis and the squid Doryteuthis gahi ^[5].

In Peru, an adult raising chicks at Punta Atico, Arequipa, carried a GPS in June 2018: it made 3 to 5 trips a day, went on average 5.63 km from the nest, with a maximum of 10 km, and its trips lasted about 40 minutes ^[5]. More than half of those trips went offshore, which suggests that in the Humboldt Current the chuita may feed on pelagic prey such as anchovy, and not only over rocky bottoms ^[5].

On Pirén islet, in southern Chile, it shares the colony with the imperial shag; stable isotopes showed that its isotopic niche is narrower and overlaps by 95.7 % with that species outside the breeding season and by 89.6 % during it. Unlike the imperial shag, which disperses outside the breeding season, the chuita is resident all year ^[10].

In Peru it is classed as Endangered in the official list of threatened wildlife species ^[4]. The national Red Book explains that, although it is common along much of the coast and on the guano islands, it breeds at scattered sites, with few individuals per locality, usually fewer than 100, and that El Niño hits its populations hard ^[3].

After the 1997-1998 El Niño its numbers fell by 73 % at 8 localities in southern Peru, and at 10 localities in the north and centre they dropped from 3229 to 69 individuals between 1968 and 2000 ^[3]. In 2000 the Peruvian population was estimated at 1500 to 2100 birds, and in the north of the country the declines have been linked to the die-off of kelp beds as the sea warmed ^[2].

Its threats in Peru are entanglement in fishing nets, the harvesting of shellfish and kelp in the intertidal zone, the hunting of adults and chicks, pollution near scallop farms and competition for food with shore fishers ^[3]. Hence the recommendations to control the harvest of invertebrates and kelp outside protected areas, to ban kelp harvesting near the guano islands and headlands, and to control waste and noise at scallop farms ^[3].

The bird tracked at Punta Atico went daily beyond the 2-nautical-mile belt that protects the guano islands and headlands reserve, and many sites where the species nests on the Peruvian coast have no protection at all ^[5]. Worldwide, a 2004 study estimated fewer than 15000 individuals, more than 70 % of them in Chile ^[6].

In Chile, according to fishers, adults are eaten and their eggs and chicks are also taken; in Region X it is hunted by fishers and by shellfish and seaweed gatherers, and of 20 fishers interviewed there, 4 said they hunted it for food or as bait for the crab Homalaspis plana ^[6]. In that same region, one group of fishers caught some 300 birds in a single outing ^[6]. In Peru, the hunting of adults and chicks is listed among its threats ^[3].

The 2026-2031 master plan of the Reserva Nacional Sistema de Islas, Islotes y Puntas Guaneras marks breeding and resting zones of the chuita on Guañape Norte island, Don Martín islet, the cliffs of Mazorca island, Asia island and the Ballestas islands. In the Guañape Norte zone tourism and motorboat traffic are not allowed; in several of the others landing to harvest resources is not allowed, research and photography need the reserve's authorisation, and at the Ballestas sailing inside the caves is forbidden ^[11]. In 2018 the species was breeding at Punta Atico, Arequipa, a headland of that same reserve, where the fieldwork was done under SERNANP permits ^[5],[11].

In the Reserva Nacional de Paracas, its 2025-2030 plan mentions the chuita on the cliffs of Punta Arquillo, where research, photography and filming are allowed only exceptionally and with prior authorisation, and entry on foot or by vehicle is not allowed ^[12]. In the north, 36 bird species have been recorded on Isla Foca, in Piura, the chuita among them, according to the 2026-2031 plan of the Reserva Nacional Mar Tropical de Grau ^[13].