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Haematopus ater

Blackish Oystercatcher


Haematopus ater

Vieillot, LJP, 1825
Ostrero Negro

Family: Haematopodidae
Order: Charadriiformes
Class: Aves
Phylum / Division: Chordata
Kingdom: Animalia

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Records from Puerto Deseado

Conservation status according to BirdLife International: Least Concern


Description


Features a robust and stocky morphology, measuring approximately 43 to 48 centimeters (17 to 19 inches) in total length. The plumage is almost entirely a dark, uniform sooty-black, with the head and neck displaying a slightly deeper black coloration, while the back and wings exhibit a subtle dark brownish tinge. Its most prominent diagnostic feature is the long, powerful, laterally compressed bill of a striking bright crimson-red color. The eyes are characterized by a vibrant yellow iris highlighted by a contrasting orange-red orbital ring. In contrast to other related species, its legs and feet are a pale, fleshy pink or dull whitish color. Sexual dimorphism is virtually absent, although females often possess slightly longer and more slender bills compared to males.

Geographical distribution: Occurs predominantly along the rugged coasts of southern South America. Its range extends along the Pacific coastline from northern Peru (Illescas Peninsula) southward through the entire length of Chile, encompassing the Juan Fernández Archipelago and reaching Cape Horn. Along the Atlantic slope, it is distributed from the southern portion of Buenos Aires province in Argentina, continuing southward along the entire Patagonian coast down to Tierra del Fuego. Furthermore, highly stable and significant breeding populations are resident in the Falkland Islands. Vagrant or occasional individuals have been recorded further north, reaching the southern shores of Brazil and Uruguay.

Habitat: Is strictly associated with wave-swept rocky shorelines, marine cliffs, and pebble or shingle beaches. Unlike other oystercatchers, this taxon almost entirely avoids muddy estuaries, calm coastal lagoons, and extensive fine sand beaches. It exhibits a strong preference for the intertidal zones of high-energy rocky coasts where the tides expose wide platforms, providing optimal foraging grounds while remaining entirely dedicated to the marine littoral environment.

Feeding: Possesses a highly specialized carnivorous diet focused almost exclusively on marine invertebrates of the rocky intertidal zone. Its primary food sources are bivalve and gastropod mollusks, with a strong preference for limpets (Fissurella species) and mussels (Mytilus species). Using its chisel-like bill, it is capable of deftly prying clinging limpets off rock surfaces or sliding its bill between the shells of mussels to sever the adductor muscle. Additionally, it regularly preys upon sea urchins, chitons, small crabs, and polychaetes found in tide pools during low tide.

Behavior: Displays territorial and mostly solitary or pair-dwelling habits, rarely forming large flocks outside the post-breeding season. When navigating slippery, algae-covered rocks, it walks with deliberate, heavy-footed steps, occasionally bobbing its tail. Its flight is strong, direct, and swift, featuring rapid wingbeats close to the water´s surface. While it is a noisy bird that utters sharp, high-pitched whistling calls when alarmed, it is generally less gregarious and vocal than its pied counterparts. Territory defense is fierce, involving complex bowing displays, piping ceremonies, and aerial chases to expel intruders.

Nesting: The breeding season takes place between October and January. This species is a solitary nester, establishing its breeding territory directly on the ground in open areas near the high-water mark, such as rocky ledges, gravel terraces, or shell beds. The nest is a simple, shallow scrape in the ground, which is often sparsely lined with small pebbles, shell fragments, or pieces of dried kelp. Females typically lay one to two eggs (rarely three), which are olive, stone-colored, or pale brown, heavily speckled with dark brown and black markings to provide superb camouflage against the substrate. Both sexes share incubation duties for approximately 24 to 27 days, and both actively participate in rearing and feeding the semi-precocial chicks, which leave the nest shortly after hatching but remain dependent on their parents for several weeks to master complex foraging techniques.

Conservation status: Is currently evaluated as a species of Least Concern (LC) on the IUCN Red List of Threatened Species. Although it maintains a relatively large overall population and an extensive range, local populations are highly vulnerable due to their extreme habitat specialization. Present threats include coastal urban development, human disturbance at nesting sites from unregulated tourism, predation of eggs and chicks by introduced invasive species such as feral dogs, cats, and rats, and the severe impact of oil spills on the fragile intertidal ecosystems.



Compilation and publication: EcoRegistros – 06/08/2026




Geographic distribution


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Species photographs

Last published photographs

Foto
Photography ID: 668750
  Adult

Puerto Deseado
Santa Cruz
Argentina
01/14/2026
Adrian Dario Barboza
Foto
Photography ID: 666498
  Adult

Puerto Deseado
Santa Cruz
Argentina
12/15/2025
Hernán Tolosa
Foto
Photography ID: 662990
 
Puerto Deseado
Santa Cruz
Argentina
12/14/2025
Jorgelina Lopez
Foto
Photography ID: 633518
  Adult

Puerto Deseado
Santa Cruz
Argentina
04/05/2025
Carlos De Biagi
Foto
Photography ID: 633383
  Adult

Puerto Deseado
Santa Cruz
Argentina
04/04/2025
Carlos De Biagi
Foto
Photography ID: 633354
  Adult

Puerto Deseado
Santa Cruz
Argentina
04/04/2025
Carlos De Biagi
Foto
Photography ID: 633339
  Adult

Puerto Deseado
Santa Cruz
Argentina
04/03/2025
Carlos De Biagi
Foto
Photography ID: 621139
♂ ♀
  Adult

Puerto Deseado
Santa Cruz
Argentina
02/05/2025
Guillermo Alejandro Nelson Tarapow
Foto
Photography ID: 621045
♂ ♀
  Adult

Puerto Deseado
Santa Cruz
Argentina
02/03/2025
Guillermo Alejandro Nelson Tarapow
Foto
Photography ID: 595504
 
Puerto Deseado
Santa Cruz
Argentina
04/19/2023
Adrian Braidotti
Foto
Photography ID: 595428
 
Puerto Deseado
Santa Cruz
Argentina
04/19/2023
Adrian Braidotti



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Page 1
Record IDDateExact timeCountryProvince / departmentPlaceFilmedPhotographedRecorded vocalObservedHeardWounded or deadNumber of individualsUser or BibliographyDetail
241912714/01/2026ArgentinaSanta CruzPuerto DeseadoAdrian Dario Barboza
241254118/12/2025ArgentinaSanta CruzIsla Pingüino, Puerto DeseadoHernán Tolosa
240091618/12/2025ArgentinaSanta CruzIsla Pingüino, Puerto DeseadoJorgelina Lopez
241282915/12/2025ArgentinaSanta CruzDesagüe de Carsa, Puerto DeseadoHernán Tolosa
241251514/12/2025ArgentinaSanta CruzRia Puerto Deseado, Puerto DeseadoHernán Tolosa
239970814/12/2025ArgentinaSanta CruzRia Puerto Deseado, Puerto DeseadoJorgelina Lopez
228495605/04/2025ArgentinaSanta CruzPuerto DeseadoCarlos De Biagi
228443504/04/2025ArgentinaSanta CruzReserva Natural Ria Deseado, Puerto DeseadoCarlos De Biagi
228440404/04/2025ArgentinaSanta CruzCamino a cueva de los leones, Puerto DeseadoCarlos De Biagi
228438903/04/2025ArgentinaSanta CruzReserva Natural Ria Deseado, Puerto DeseadoCarlos De Biagi
Page 1

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Recommended citation
Please use the following reference when citing this species account.
EcoRegistros. 2026. Blackish Oystercatcher (Haematopus ater) – Species account. Accessed from www.ecoregistros.org on 14/09/2026.