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Complejo Lagunar Ojo de Liebre -
Guerrero Negro

Site Facts

Country,State, Province/Region:

Mexico, State of Baja California Sur, Municipality of Mulegé

Relative Location:

Forms part of the El Vizcaíno Biosphere Reserve


27°53’46.17” N, 114°09’03.57”W



Basis for Designation:

Hosts over 30% of the biogeographic population of three species: Marbled Godwit (Limosa fedoa) [50%]; subspecies of Red Knot (Calidris canutus roselaari) [32%]; and subspecies of Short-billed Dowitcher (Limnodromus griseus cairinus) [68%]


163,765 hectares (404,500 acres)


September 2000, International Importance (Guerrero Negro); expanded and re-designated April 2009, Hemispheric Importance (Ojo de Liebre – Guerrero Negro)

Site Owner/Steward:

National Commission of Protected Natural Areas (CONANP)

Site Partners:

El Vizcaíno Biosphere Reserve, Exportadora de Sal S.A. de C.V., Autonomous University of Baja California Sur, and Pronatura Noroeste


Everardo Mariano Melendez
Director, El Vizcaíno Biosphere Reserve

Roberto Carmona
Professor and Researcher
Autonomous University of Baja California Sur

Gustavo Danemann
Regional Director
Pronatura Noroeste


This lagoon complex is located in the community of Guerrero Negro, Municipality of Mulegé, in the state of Baja California Sur. In September 2000, the 20,102-hectare (49,651-acre) Guerrero Negro wetland was designated a WHSRN Site of International Importance, nominated by Exportadora de Sal S.A. de C.V., a salt-extraction company with a concession in the area. Through scientific research and monitoring activities in the area since, partners discovered that the larger complex of Ojo de Liebre - Guerrero Negro (163,765 hectares [404,500 acres]) meets the criteria for a Site of Hemispheric Importance by hosting over 30% of the biogeographic population of not one, but three species: Marbled Godwit (Limosa fedoa) [50%]; subspecies of Red Knot (Calidris canutus roselaari) [32%]; and subspecies of Short-billed Dowitcher (Limnodromus griseus cairinus) [68%]. The area supports 31 shorebird species overall, including regionally important populations (> 1%) of seven species.

An expanded Site Profile for Ojo de Liebre - Guerrero Negro will be available soon!

Guerrero Negro

The WHSRN site Exportadora de Sal - Guerrero Negro (Guerrero Negro, for short) is located in the western half of the Baja California Peninsula, Mexico. It is adjacent to Ojo de Liebre Lagoon and is within the El Vizcaíno Biosphere Reserve. The site’s lands are the property of the Benito Juárez and Gustavo Díaz Ordaz Ejidos. The numbers of shorebirds registered here make this salt mine one of the most important wetlands on the Baja California Peninsula. Within the salt mine area, 95 species of birds have been observed, including 27 species of shorebirds.

The Guerrero Negro salt mine is the largest in the world, with an annual production of 7 million tons. The company bases its production on the solar- and wind-induced evaporation of saltwater that is contained in a series of concentrated areas where there are no sea-level influences. Additionally, the physical-chemical conditions and biological characteristics of the areas are maintained as stable throughout the year, which is an indispensable requirement for ensuring the salt production process happens adequately. Such stability has allowed diverse communities of fish and invertebrates to become established, which in turn serve as a food source for birds. The region is characterized by its aridness, with winter rains not exceeding 100 millimeters per year, on average.

This WHSRN site is used by at least 100,000 shorebirds throughout the year. The most abundant species are the western sandpiper (Calidis mauri) and red-necked phalarope (Phalaropus lobatus). Additionally, Guerrero Negro is the most important site in Mexico for the red knot (Calidris canutus), and one of the most important places for wintering marbled godwits (Limosa fedoa).

Exportadora de Sal’s installations are within the Ojo de Liebre lagoon complex, which is considered an Important Bird Conservation Area (AICA, by its Spanish name)—Number 101, Category NA-4-C (which means the site contains more than 15,000 waterfowl, or 7,5000 pairs of one or more species of waterbirds, or 100,000 shorebirds).

The only potential threats to the site would originate from land-tenure problems between the ejidos and federal authorities.

Ecology and Conservation

An expanded Site Profile for Ojo de Liebre - Guerrero Negro will be available soon!

Guerrero Negro

The area of study is found in the western half of Mexico’s Baja California Peninsula, in the Sebastian Vizcaino Bay. Three large bodies of water are located in this bay: Manuela Lagoon (600 hectares), Ojo de Liebre Lagoon (57,100 hectares), and Guerrero Negro Lagoon (21,100 hectares). This lagoon complex is next to the El Vizcaíno desert. The region’s climate is arid, with winter rains that usually do not exceed 100 millimeters per year. The predominate vegetation is xerophilic matorral and is, in general, low and dispersed. The average annual temperature ranges between 18 and 22 degrees Centigrade.

The Salt-mining Business at the Site

To the east of Oje de Liebre Lagoon is the Guerrero Negro salt mine, run by Exportadora de Sal, S.A. de C.V. This is the largest salt-mining business in the world, which bases its production on the solar and wind evaporation of saltwater. Its average annual production is 7 million tons. The salt mine is 51 percent owned by the Mexican Federal Government and 49 percent owned by a private Japanese company, Mitsubishi. The production process involves pumping saltwater to concentration areas that encompass 30,000 hectares; however, it has been observed that only 20,102 hectares are being used by birds. The primary areas (S-1A and A-1) receive water pumped directly from Ojo de Liebre Lagoon, with salinity similar to that of mid-sea (3.5-3.8 %), whereas the salinity in the last concentration areas reach 25 %. The areas are separated by a series of dikes, and the salinity within each area is maintained at a constant. The brine resulting from the evaporation process is pumped to a series of crystallization vessels, where it continues the process. Once most of the water has evaporated, the salt precipitates and is harvested. In general, the birds don’t use the crystallization vessels nor the concentration areas with the greatest salinity (areas 10 to 13). The salt mine, for the most part, presents substrates that are sandy and muddy, and not subjected to the regimen of the sea. However, it’s possible to present slight variations in the substrates’ levels, due to the activity of the pump, which intensifies in the summer.

The Human Population
Some 15 kilometers north of the salt mine is the town of Guerrero Negro, which has a population of approximately 12,000 inhabitants. The economy of this place revolves around three activities: fishing in the Ojo de Liebre Lagoon , ecotourism (particularly gray-whale watching), and salt extraction. Exportadora de Sal directly employs an average of 1,000 people.

The Birds
The Guerrero Negro salt mine constitutes a high-quality, artificial habitat and therefore is of great importance for migratory and resident birds. The WHSRN site is used by at least 100,000 shorebirds throughout the year, making it a site of international importance. The maximum abundance at Guerrero Negro is actually 110,500 shorebirds. The most numerous species are: red-necked phalarope (Phalaropus lobatus; 58,000 birds), western sandpiper (Calidris mauri; 26,000), dunlin (Calidris alpina;13,000), dowitchers (Limnodromus spp.; 12,000), and marbled godwit (Limosa fedoa; 5,400). Recently, (2005-2006) important numbers of red knots (Calidris canutus) were observed using the salt mine, presumably the subspecies C. c. roselaari; the maximum observed was 3,000 individuals, which corresponds to 15% of this subspecies’ estimated total population. Additionally, at least 10 species (see Special Information section) nest at the salt mine; among those that stand out is the California least tern (Sternula antillarum browni), a species categorized as in danger of extinction.

Management and Protection
The area concessioned to Exportadora de Sal receives effective and permanent surveillance by the company, and access to the area is restricted. This prevents any type of physical alteration to the environment used by birds, as well as any extraction of organisms (fish, shrimp, Artemia, etc.) that the birds feed upon. Additionally, the area is within the El Vizcaino Biosphere Reserve, where the only potential threats to the site would be those arising from problems related to land tenure--and conflicts have already arisen between the ejidatarios and the salt mine company with respect to prices, which should be resolved through the temporary occupation of land agreement.

Given that an indispensable requirement for adequate salt production is the maintaining of stable conditions, a management plan is not necessary as long as the salt mine remains in operation.

As part of a program for researching birds’ use of the region in general, to date continuous studies (monthly censuses) have been carried out since 2004. Additionally, capture studies also have been conducted, using mist nets, and have focused on two shorebirds species—western sandpiper (Calidris mauri) and red knot (C. canutus).

Listed in the Special Information section is published research that doesn’t directly tackle topics regarding shorebirds and the most relevant results from recent field work. Below is a list, with explanatory comments, of the most relevant studies regarding shorebirds:

  • Danemann et al. (2002) described the species composition, variation in abundance, and timing of migration for the shorebirds at the salt mine. They registered 26 species, of which Phalaropus lobatus (58,000) and Calidris mauri (26,000) were the most abundant.
  • Carmona et al. (2006) determined the abundance of Calidris canutus at the salt mine. The red knot favored one of the first concentration areas (Salitrales 1A). Additionally, the researchers evaluated the effect of sea level on this species’ abundance. The greatest numbers were observed in October 2005 (2,900 birds maximum), which are also the highest ever registered in Mexico.
  • Morales-Gopar and Carmona (2006) described a new feeding technique of the western sandpiper (Calidris mauri). They encountered the birds “feeding in flight.” This foraging behavior allows the sandpipers to access the marine invertebrates (mainly Artemia spp.) and some insects.
  • Recently, Arce (in revision) determined the utilization for Calidris mauri in a natural area of Guerrero Negro (a beach on Ojo de Liebre Lagoon) and in an artificial area (a salt-mine concentration area). Arce found that the population structure by gender was 3:1 (male: female); the global population structure by age was 1:1, but distinct between the two wetlands (76% of juveniles at the beach and 76% of adults at the salt mine).
  • Ayala-Perez (in revision) evaluated the relationship of shorebird abundance with seawater levels at a natural area and at an artificial one. Ayala-Perez registered 25 species of shorebirds using the zone, with Calidris mauri the most abundant at the beach (63%) as well as at the salt mine (46.3%). The birds were more abundant at the salt mine at high seawater levels, and at low levels at the beach. There were seasonal differences; the seawater level affected the birds more during periods of high energetic demands (fall and spring).

Special Information

An expanded Site Profile for Ojo de Liebre - Guerrero Negro will be available soon!

Guerrero Negro

The high abundances of red knot observed at the salt mine motivated different researchers to visit the site (October 2006) with the intention of conducting the first banding effort of this species in Mexico. At the end of October 2006, the researchers met at concentration area Salitrales 1A: six from outside Mexico (N. Clark, H. Sitters, R. Robinson and J. Clark from England, and B. Harrington and N. Atkins from the United States) and 10 from Mexico (all within the Bird Program at the Autonomous University of Baja California Sur, under the direction of Roberto Carmona). They captured and banded 194 red knots, presumably of the subspecies C. c. roselaari, and adults predominantly (83%). The observed results confirmed that the Guerrero Negro salt mine is a site of major importance for this species in Mexico. Also, the re-observation of banded birds has begun to give researchers a description of this subspecies’ migratory routes. For example, recent data confirm the presence of banded birds not only at the salt mine but also on the coasts of Washington and Alaska. It is expected that this banding effort will be repeated in October 2007, fundamentally with participation from the same researchers. Other ornithological studies carried out at the Guerrero Negro salt mine exist, of which the following stand out:

  • Danemann and Carmona (2000) determined the species of birds that reproduce within the salt mine installations are: Falco peregrinus, Sternulla antillarum browni, Passerculus sandwichensis, Pandion haliaetus, Charadrius alexandrinus, Haematopus palliatus, Hydroprogne caspia, Thalasseus maximus, Gelochelidon nilotica and Rynchops niger. The first three are protected by the Mexican Government (under categories of special protection, in danger of extinction, and threatened, respectively). For the last two species listed, this is the first register of their reproduction in Baja California Sur.
  • Carmona and Danemann (2000) determined the temporal abundances of four species of Pelecaniformes (Pelecanus erythrorhynchos, P. occidentalis, Phalacrocorax auritus and Ph. penicillatus) at the salt mine. The most abundant species was Ph. auritus, followed by P. erytrhorhynchos and P. occidentals; Ph. penicillatus was observed only occasionally. This work demonstrates that the salt mine is an important point for the post-reproductive dispersion of these species.
  • Peralta et al. (2002) studied the ecological attributes of 13 species of resident waterbirds at the salt mine. The most abundant species was Phalacrocorax auritus, and the species most widely distributed was Larus occidentalis. Peralta found evidence of a negative relationship between the richness and abundance of these species and salinity.
  • Peralta et al. (2004) studied the depredation of the western gull (Larus occidentalis) on the eared grebe (Podiceps nigricollis) within the salt mine. Some 35 successful attacks were registered—the first ever of such recordings for grebes.
  • Cuéllar-Brito (in revision) studied the attributes of the eared grebe’s (Podiceps nigricollis) migratory use of the salt mine, and registered up to 16,000 wintering grebes there. The sex ratio was 1:1, and adults outnumbered sub-adults and juveniles. Depredation on grebes by gulls was also observed (in fact, 6% of the population was depredated), but the gull species involved was always the herring gull (Larus argentatus).


Contact Us

Everardo Mariano Melendez
Director, El Vizcaíno Biosphere Reserve

Gustavo Danemann
Regional Director
Pronatura Noroeste

Martín Domínguez
Manager of Quality, Ecology, and Security
Exportadora de Sal

Roberto Carmona
Professor and Researcher
Autonomous University of Baja California Sur

Nallely Arce
Autonomous University of Baja California Sur

Victor Ayala Perez
Autonomous University of Baja California Sur

Andrea Cuéllar
Autonomous University of Baja California Sur