Ansenuza

Parque Nacional Ansenuza, together with its accompanying national reserve, protects roughly 661,416 hectares (about 6,614 km²) of northeastern Córdoba Province, Argentina, centered on Laguna Mar Chiquita, also called Mar de Ansenuza, and the wetlands of the lower Río Dulce. ^[1] Mar Chiquita is the largest salt lake in South America and one of the largest in the world, a vast endorheic (closed-basin) saline lake whose level and salinity swing widely between wet and dry cycles. Created on June 30, 2022 by National Law 27,673, Ansenuza is among Argentina's largest national parks and one of the most important sites on the continent for flamingos and migratory shorebirds. ^[2] It is an inland salt lake and Ramsar wetland, administered by the Administración de Parques Nacionales.

Ansenuza is above all a bird paradise, hosting more than 300 recorded bird species and enormous concentrations of waterbirds. ^[1] It is one of the few places on Earth where all three South American flamingo species occur together: the Chilean flamingo (Phoenicopterus chilensis, the most abundant, present year-round in populations that can reach hundreds of thousands), the Andean flamingo (Phoenicoparrus andinus) and James's flamingo (Phoenicoparrus jamesi). The lake and the Río Dulce marshes are a critical stopover and wintering ground for vast numbers of migratory shorebirds traveling between the Arctic and southern South America; over 500,000 shorebirds use the site annually. Beyond birds, the park supports fish adapted to saline and brackish water, numerous reptiles and amphibians, and Chaco and grassland mammals in the surrounding wetlands and woodlands, making it a hotspot of biodiversity in central Argentina.

The park spans a transition between the vast open salt lake, its surrounding salt flats and halophytic vegetation, and the freshwater marshes and forests of the Río Dulce delta. Around the saline shores, salt-tolerant plants such as jume and other halophytes form low, sparse cover on the mudflats. Toward the northeast, the Bañados del Río Dulce sustain extensive freshwater marshes, reed beds and aquatic vegetation, grading into dry Chaco woodland with algarrobo, quebracho and other native trees on higher, drier ground. This gradient from hypersaline lakebed through wetlands to Chaco forest creates a mosaic of habitats, and the shifting water levels of the lake continually reshape the extent of open water, marsh and exposed flats that the vegetation follows.

Laguna Mar Chiquita occupies a large tectonic and endorheic depression in the plains of northeastern Córdoba, a closed basin with no outlet to the sea. ^[1] It is fed mainly by the Río Dulce from the north and the Suquía and Xanaes (Segundo and Tercero) rivers, and because water leaves only by evaporation, dissolved salts accumulate, making the lake strongly saline, historically ranging from around 40 up to over 250 grams of salt per litre as levels rise and fall. The lake's surface area and depth fluctuate dramatically across multi-year wet and dry cycles, exposing and flooding broad expanses of salt flats and mud. Surrounding sediments are fine wind- and water-borne deposits of the Pampas and Chaco lowlands, and the Río Dulce has built extensive wetlands and a delta at the lake's northern end.

The park has a warm, semi-arid to subhumid climate with hot summers, mild winters and a pronounced seasonal rainfall pattern concentrated in the warmer months. High summer temperatures and strong evaporation over the shallow, wide lake drive the concentration of salts and the seasonal shrinking of open water, while winter is drier and cooler. Rainfall is variable from year to year, and multi-year wet and dry cycles cause the lake to expand and contract markedly, a defining feature of its ecology. Winds across the exposed flats can raise salt and dust, and the climate's strong seasonality and interannual swings directly govern the availability of habitat for flamingos and shorebirds, whose numbers respond to changing water levels and food supply.

The Mar Chiquita region was inhabited by Indigenous peoples including Sanavirón and Comechingón groups, and the name Ansenuza is linked to Indigenous tradition for the great lake. In colonial and later times the area supported cattle ranching, fishing and salt gathering, and the lakeshore town of Miramar developed in the 20th century as a spa and health resort famed for its saline waters, later affected by dramatic changes in the lake's level. Today several hundred rural families live around the wetlands, engaged in cattle raising, fishing, small-scale farming and increasingly tourism. This long human presence, combined with recognition of the area's outstanding birdlife, built the local and scientific support that ultimately led to national park protection.

Parque Nacional Ansenuza was created on June 30, 2022 by National Law 27,673, following years of work by conservation groups, the province of Córdoba, the national government and organizations such as Aves Argentinas and international partners. ^[1] The designation established both a national park and a national reserve covering the lake and the Bañados del Río Dulce, one of the largest protected areas in Argentina. The site had already been recognized internationally as a Ramsar wetland and as a hemispheric reserve for shorebirds before the park's creation, and its establishment formalized long-standing efforts to safeguard this globally important salt lake and wetland complex for its extraordinary concentrations of waterbirds.

The overwhelming attraction of Ansenuza is its birdlife, above all the spectacle of tens of thousands of flamingos feeding on the shimmering salt lake, best seen from the shores near Miramar and other access points around the lake. The town of Miramar de Ansenuza serves as the main gateway, offering lakeshore views, beaches, boat outings and birdwatching. Elsewhere, the Bañados del Río Dulce and the northern wetlands provide opportunities to see immense gatherings of migratory shorebirds, herons, ducks and other waterbirds. The sheer scale of the lake, its changing colors and the salt-encrusted shorelines make for dramatic landscapes, and the park is being developed for nature tourism with viewpoints and guided experiences focused on its avian riches.

Miramar de Ansenuza on the southern shore, about 66 kilometres from the park's core wetlands and roughly 150 kilometres northeast of the city of Córdoba, is the principal base for visitors, with hotels, restaurants and services geared to lake tourism. ^[1] Access is by paved routes from Córdoba and other regional towns, and local operators offer boat trips and birdwatching excursions on the lake. As a recently created park, formal visitor infrastructure within the protected area is still developing, so many activities are organized from Miramar and other lakeside communities. Visitors should plan for a remote, sun-exposed environment, bring sun protection and water, and coordinate with local guides and park information points for the best wildlife viewing.

Ansenuza safeguards one of the most important wetland and salt-lake ecosystems in South America, a Ramsar site and a Western Hemisphere Shorebird Reserve Network (WHSRN) site of hemispheric importance whose flamingo and shorebird populations depend on the health of the lake and the Río Dulce wetlands. ^[1] Key conservation concerns include maintaining the river flows and water quality that sustain the wetlands, which are threatened by upstream water use, agricultural expansion and pollution, and managing the natural extremes of the lake's fluctuating levels. The park model integrates conservation with sustainable local livelihoods and nature tourism for the surrounding communities. National park protection strengthens habitat security, research and monitoring, and regional cooperation to keep this endorheic basin functioning for its globally significant waterbird populations. It is a national park and Ramsar wetland, not a UNESCO biosphere reserve.