Brown pelican

Pelecanus occidentalis is a pelican of the family Pelecanidae described by Linnaeus in 1766 ^[1]. In Peru it is called «pelícano pardo» ^[2]. It is a seabird of nearshore waters that fishes by plunge diving and nests in colonies located offshore ^[3]. The IUCN Red List classifies it as Least Concern ^[4].

It is a seabird of nearshore waters, and one of only two pelican species that live year-round in marine environments ^[3]. Its capture method and jaw shape let it take large volumes of prey at once, something closer to rorqual whales than to other seabirds ^[3].

The species is divided into several subspecies. In the North American Pacific, Pelecanus occidentalis californicus breeds in subpopulations are found in the Southern California Bight, the southern Pacific side of Baja California, the Gulf of California and the Mexican mainland coast; in 2006 those of the Gulf of California and the Mexican mainland estuarine zone held 76.4% of the nesting birds of that subspecies ^[5]. In the Atlantic, Pelecanus occidentalis carolinensis nests in colonies in the northern Gulf of Mexico ^[3].

Outside those breeding areas there are records in the Caribbean and in the South American Pacific: in November 2022 an avian influenza outbreak affected 200 brown pelicans in Venezuela, and in February 2023 400 died on Gorgona Island, near the Pacific coast of Colombia ^[6]. Further south, the Pacific coast from southern Ecuador and along Peru is the range of Pelecanus thagus, another pelican species ^[7].

It is a coastal bird that nests in colonies located offshore, with anywhere from hundreds to thousands of nests ^[3].

It lays up to 3 eggs, which hatch one after another at 2-day intervals, incubates them for about 30 days and usually raises 1 or 2 chicks ^[3]. Chicks fly at about 70 days and leave the colony 70 to 90 days after hatching; both parents care for and feed the young, several times a day ^[3].

In 9 colonies of the northern Gulf of Mexico, studied from 2013 to 2015, raising one chick to fledging took about 800 g of food a day, close to 56000 g from hatching to flight ^[3]. The biomass delivered to the nest explained more than 90% of the variation in productivity between colonies ^[3].

In the Pacific subspecies, El Niño-Southern Oscillation strongly affects the intensity and success of breeding each year, with a somewhat weaker effect to the north ^[5]. Nest attempts in the south of the Midriff Islands region of the Gulf of California fell to extreme lows during the warming of 2014 to 2016 ^[5].

It fishes by plunge diving and takes large volumes of prey at once, and the authors suggest that targeting highly concentrated prey, regardless of energy content, could be a way of maximizing the biomass delivered to the nest ^[3].

In the northern Gulf of Mexico, 641 meals regurgitated by chicks were analysed, 98 kg in all, with 46 prey species from 25 families, and Brevoortia patronus supplied 61% of the biomass ^[3]. That species made up 60 to 84% of chick diets at colonies in the core of its range and under 40% at those on its margins ^[3].

The authors conclude that the quantity of prey, not its energy quality, is what most limits breeding: the energy content of meals varied little between colonies and did not explain differences in breeding success ^[3]. Changes in the biomass or distribution of forage fish can therefore affect its reproduction ^[3].

The IUCN Red List classifies it as Least Concern ^[4]. In the United States, breeding failures associated with DDT pollution led to the species being placed on endangered species lists in 1970 and 1971, and in 2009 it was removed from the federal and California lists ^[5].

In Mexico, the Pacific subspecies has been covered by the norm NOM-059-SEMARNAT-2010 since 2010 ^[5]. Between 2014 and 2016, an anomalous warming of the Pacific known as the Blob depressed its breeding across its whole range, and human disturbance and commercial fishing may have worsened that effect in some areas ^[5].

In Peru, the master plan of Los Manglares de Tumbes National Sanctuary mentions the pelican among the three bird species that D. S. 034-2004-AG considered threatened ^[2]. Its list of the sanctuary's birds assigns it no category under D. S. 004-2014-MINAGRI ^[2].

Not medical advice. For a sting, a poisoning or an allergy, seek medical care.

In the highly pathogenic avian influenza H5 epizootic in Latin America, one of the first outbreaks in wildlife occurred in November 2022 in Venezuela and affected 200 brown pelicans; in February 2023, 400 died on Gorgona Island, Colombia ^[6].

In Peru about 558000 seabirds of at least 14 species were found dead, mainly from December 2022 to June 2023; among the most frequently recorded the study cites the pelican Pelecanus thagus (58000 individuals) and not Pelecanus occidentalis ^[6].

In Peru, the master plan of Los Manglares de Tumbes National Sanctuary, on the north coast, includes the brown pelican in its list of the sanctuary's birds ^[2]. Between 2015 and 2020 SERNANP raised to 158 the bird species recorded there ^[2].