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San Antonio Bay

Site Facts

Country, State, Province/Region:
Argentina, Province of Río Negro

Relative Location:
Northern Patagonia, from the Baliza San Matías (to the east) to El Sótano, including about 45 km of beaches.

40º 45’ S, 64º 55’ W

International Site

Basis for Designation:
More than 100,000 shorebirds per year, including 40,000 Red Knots (Calidris canutus), approx. 25% of the biogeographic population. In recent years, fewer knots have been observed in the area, reflecting the dramatic declines that have been recorded for the species: it is estimated that at least 50% of the rufa population uses the area, underlining its importance for the future conservation of the species.

65,500 hectares (161,853 acres)


Site Owner/Steward:
Province of Río Negro

Site Partners:
Fundación Inalafquen, Consejo Provincial de Ecología de la Provincia de Río Negro

Dr. Daniel López
President, San Antonio Oeste Municipal Council

Sr. Jorge Sanchez Pino
Secretariat of Production and the Environment, Municipality of San Antonio Oeste

Sr. Hernan Povedano
Rio Negro Department of Protected Areas

Patricia González
Fundación Inalafquen

About Us

San Antonio Bay – Bahía de San Antonio in Spanish – is a coastal marine protected area in the northwest corner of San Matías Gulf, in the northern part of Patagonia, Argentina. Xerophytic (desert tolerant) shrub vegetation called "monte" thrives in the uplands of this semi-desert part of Río Negro Province.

Tidal Feast

High tidal ranges of 9.3-meters (30.5 feet) are the dominant feature of the coast. The tides are an ecological engine that exposes vast intertidal habitats perfect for shorebirds twice every day. At low tide, the water can withdraw as far as 7 km (4.3 miles) from the coastal dunes, uncovering rich feeding areas used by shorebirds: 

  • Salt marshes and wide mudflats (with or without crabs) in the Bay itself;

  • Broad sand flats in the mouth of the channel connecting San Antonio Bay to San Matías Gulf (Banco Reparo and Banco Lobos);

  • Broad rocky surfaces, known as "restinga", along the Gulf shore, which are covered with small mussels that shorebirds favour (Los Alamos and El Oasis). The particular type of restinga found at San Antonio occurs at few other places on the coast of Argentina, emphasizing the special importance of the area;

  • Sand beaches (See Map and Pictures)


The richness and diversity of feeding and resting areas make San Antonio Bay a key migratory stopover for northbound and southbound shorebirds. An estimated 25-50% of the hemisphere’s Red Knots Calidris canutus rufa that winter in Tierra del Fuego stop here on their northward flight to their breeding grounds.

Two-banded Plover (Charadrius falklandicus) and American Oystercatcher (Haematopus palliatus) breed here. Other seabirds and waterfowl also nest in this area, including South American Tern (Sterna hirundinacea) and Kelp Gull (Larus dominicanus). Endemic landbirds such as Sandy Gallito (Teledromas fuscus) and Yellow Cardinal (Gubernatrix cristata) make use of adjacent uplands. San Antonio Bay is an important nursery for mollusks and fishes, some of them of high commercial value.

Popular for People and Wildlife

At San Antonio, rainfall averages 310 mm (12.2 in) a year; mean annual air temperature is 11.7º C (53º F). In early October, shorebirds arriving from the Arctic share the landscape with Southern Right Whales. In March, during peak shorebird migration, the climate is quite mild, with daily high temperatures around 26º C (79º F) and lows around 13º C (55º F). Tourists also find San Antonio very agreeable at this time of year, and it has become a destination for beachgoers and nature lovers who appreciate the richness of sea life: dolphins and Sea Lions, spectacular flocks of shorebirds swooping over the flats at low tide, and hundreds of colored Burrowing Parrots Cyanoliseus patagonus) flying over the town and cliffs where they nest. They call San Antonio the "bluest gulf of the continent" because of the deep blue color of the sky and the sea.

In the News

Red Knot Reunions

Shorebird Illustration Competition

Ecology &Conservation

San Antonio Bay became a protected provincial natural area in 1993, the same year it was recognized as a Site of International Importance by the Western Hemisphere Shorebird Reserve Network (WHSRN). Birdlife International designated it an Important Bird Area (IBA) in 2004. It is also a potential Ramsar Site.

San Antonio Bay gained added recognition and importance in 2005 when the Red Knot (Calidris canutus rufa) was listed as threatened with extinction (Appendix I of the Convention on the Conservation of Migratory Species of Wild Animals – also known as the Bonn Convention). As a signatory, Argentina strives to protect these animals; this includes conserving or restoring the places where they live, mitigating obstacles to migration, and generally controlling factors that might endanger them.

Thanks to a provincial decree in 2008 that established the site's boundaries, a total of 65,500 hectares (161,853 acres) of habitat is now protected.

Land Use

The city of San Antonio Oeste has nearly 20,000 inhabitants. Public land ownership includes the city shoreline, beaches, and San Antonio Este Port, the commercial gateway for regional fruits, apple juices, onions, garlic and soda ash.

Potential pollution from garbage, port activities, and from a soda ash factory that began operating in 2005 are a concern.

The pristine beaches in San Antonio Bay that attract so many shorebirds also attract people. Las Grutas Beach draws 300,000 tourists every summer – a number that has increased 20% per year over the past decade. New access points, buildings, and tourist amusement facilities are being constructed along the beach. Lack of advance planning for this rapid expansion has resulted in uncontrolled tourist disturbance of critical roosting and feeding areas for migratory shorebirds.

Habitat Protection

The impact of human disturbance was successfully controlled at roosting and feeding sites at Los Alamos near Las Grutas by "environmental rangers" from Consejo de Ecología y Medio Ambiente and Municipalidad de San Antonio Oeste. They were charged with protecting shorebird roosting sites during the high summer tourist season and fall migratory shorebird season, but they also act as interpreters, disseminating information about migratory birds.

However, Banco Reparo and Península Villarino and other key areas for shorebirds do not have any protection yet.


Luckily most shorebirds arrive at San Antonio Bay as the tourist season is ending. Locals now see bird watching as an opportunity to extend the tourism season. A new Interpretation Center on shorebird migration has been developed under the Multi-National Conservation of Red Knots project, funded partially by a grant to WHSRN from the Neotropical Migratory Bird Conservation Act (USA). Trained guides are leading bird watching trips and environmental education programs for tourists, educational institutions, law enforcement, and local fishermen.

Shorebird Species List

Family Scolopacidae

*Aphriza virgata Playero de rompiente Surfird
Calidris fuscicollis Playerito de rabadilla blanca White Rumped Sandpiper
*Calidris bairdii Playerito de rabadilla parda Baird's Sandpiper
Calidris canutus Playero rojizo Red Knot
Calidris alba Playero blanco Sanderling
*Calidris pusilla Playerito enano Semipalmated Sandpiper
Limosa haemastica Becasa de mar Hudsonian Godwit
Arenaria interpres Vuelvepiedras Ruddy Turnstone
Tringa melanoleuca Playero grande de patas amarillas Greater Yellowlegs
Tringa flavipes Playero chico de patas amarillas Lesser Yellowlegs
*Numenius phaeopus Playero trinador Whimbrel

Family Charadriidae

Pluvialis dominica Chorlo dorado American Golden Plover
Pluvialis squatarola Chorlo ártico Black-bellied Plover
Charadrius falklandicus Chorlito de doble collar Two Banded Plover
Charadrius collaris Chorlito de collar Collared Plover
*Charadrius semipalmatus Chorlito semipalmado Semipalmated Plover
*Charadrius modestus Chorlito pecho canela Rufous-chested Dotterel
*Pluvianellus socialis Chorlito ceniciento Magellanic Plover
*Oreophollus ruficollis Chorlo cabezón Tawny-throated Dotterel
Vanellus chilensis Tero común Southern Lawping

* rare

Management Priorities

Since 2006, the provincial government and local institutions (Municipalidad de San Antonio Oeste, Fundación Inalafquen, Instituto de Biología Marina y Pesquera Alte. Storni, Prefectura Naval Argentina and Fundación Patagonia Natural) are working on a management plan for the natural protected area at San Antonio Bay. In 2008, by provincial decree, area limits were established that increased the protected area to 65,500 hectares (161,853 acres). Meanwhile, the first urban management plan for the area (2005) advises restricted use of land close to key shorebird areas, which include extensive dune parks. But improved protection by environmental rangers is still needed.

Fundación Inalafquen is coordinating Red Knot research with other local and international institutions including the Royal Ontario Museum, Netherlands Institute of Sea Research, Canadian Wildlife Service, Manomet Center for Conservation Sciences, and Birdlife International.


Special Information

Rare Pride Campaign

In October 2008, Fundación Inalafquen began working with Rare Conservation to develop and implement a Pride campaign. This campaign is an environmental education and social marketing initiative whose principal objective at San Antonio Bay is to reduce the use of all-terrain vehicles that create disturbances in the feeding and resting sites of resident and migratory shorebirds, especially the Red Knot. This initiative was made possible thanks to support from WHSRN, the National Fish and Wildlife Foundation, Rio Negro Ministry of Education, and the Rio Negro Council on Ecology and the Environment.  

Ecotourism at San Antonio Bay

Site partners in San Antonio Bay are working toward establishing ecotourism based on shorebird observation as an alternative to mass beach tourism which causes a lot of disturbance. They assessed the receptiveness of such an approach with tourists through pilot observation field trips. A Spanish language poster details the results:

San Antonio Bay protected area, with shorebird distribution in inter-tidal roosting and feeding areas.


Dr. Daniel López
President, Municipal Council of San Antonio Oeste

Sr. Jorge Sanchez Pino
Secretary of Production and the Environment, Municipality of San Antonio Oeste

Laura Juarez
Secretary of the Environment of Río Negro

Sr. Hernan Povedano
Department of Protected Areas of Rio Negro

Mirta Carbajal
President, Fundación Inalafquen

Pedro Morón 385
San Antonio Oeste, Río Negro 8520

Patricia González
Shorebird Biologist and Researcher, Fundación Inalafquen
Pedro Morón 385
San Antonio Oeste, Río Negro 8520