The Río Pilcomayo National Park ( es, Parque Nacional Río Pilcomayo) is a national park located in the northeastern part of the Argentine province of Formosa, on the border with

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

. Established on September 29, 1951 to protect the natural features (grasslands, marshes, creeks, lakes and forests), typical of the

Humid Chaco The Humid Chaco (Spanish: ''Chaco Húmedo'' or ''Chaco Oriental'') is tropical grasslands, savannas, and shrublands ecoregion in South America. It lies in the basin of the Paraná River, covering portions of central Paraguay and northern Argenti ...

ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of ...

, the park is included in the

Ramsar Convention The Ramsar Convention on Wetlands of International Importance Especially as Waterfowl Habitat is an international treaty for the conservation and sustainable use of Ramsar site, Ramsar sites (wetlands). It is also known as the Convention on W ...

list of wetlands of international importance This is the list of Wetlands of International Importance as defined by the Ramsar Convention for the conservation and sustainable use of wetlands, recognizing the fundamental ecological functions of wetlands and their economic, cultural, scientifi ...

Topography

The park occupies a large

plain In geography, a plain is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands ...

, which was formed when a depression in

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

crystalline rocks was filled with organic and inorganic

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sa ...

s, thus creating a

sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock. They form when long-term subside ...

. The uppermost sediment levels are of fluvial and aeolian origin. The eastern parts of the park are dominated by

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel ...

s and

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

s, creating less permeable soils, while the western parts contain soils that are coarser and more porous. There are faults that were generated during

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

of the

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

, lying parallel to the

Paraguay River The Paraguay River (Río Paraguay in Spanish, Rio Paraguai in Portuguese, Ysyry Paraguái in Guarani) is a major river in south-central South America, running through Brazil, Bolivia, Paraguay and Argentina. It flows about from its headwaters i ...

. While the park's territory is gently sloping down from west to east, there is very little variety in elevation. The subtle differences become important in times of heavy rains and floods, when the area becomes inundated with pools of water connected by channels forming in the most low-lying areas.

Hydrography

The

Pilcomayo River Pilcomayo (in Hispanicized spelling) (Quechua Pillkumayu or Pillku Mayu, ''pillku'' red, ''mayu'' river, "red river", Guarani Ysyry Araguay ) is a river in central South America. At long, it is the longest western tributary of the Paraguay River ...

, after which the park is named, is the main watercourse of the area. During the wet season, the river and its tributaries flood the nearby areas, creating large swaths of interconnected lakes and marshes, most of which are temporary. The southern end of the park contains a larger lake called Laguna Blanca, which is a habitat for many

waterfowl Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which i ...

species and a resting point for migratory bird species coming from the Northern Hemisphere.

Climate

The park is located in a subtropical zone with annual mean temperature of and annual mean precipitation of . Summer temperatures can exceed , but during winters, frost is not uncommon. Winters are dry, while precipitation peaks in March and November. The area is affected by frequent

tornado A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, altho ...

es.

Flora

For the purposes of classifying the park's types of plants, the area can be divided into 4 distinct zones. One is

savanna A savanna or savannah is a mixed woodland- grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...

, which is dominated by the Caranday wax palm, an unofficial emblem of the area, towering over a dense cover of

herbaceous plant Herbaceous plants are vascular plants that have no persistent wood, woody stems above ground. This broad category of plants includes many perennial plant, perennials, and nearly all Annual plant, annuals and Biennial plant, biennials. Definition ...

s (especially from the genus ''

Scirpus ''Scirpus'' is a genus of grass-like species in the sedge family Cyperaceae many with the common names club-rush, wood club-rush or bulrush (see also bulrush for other plant genera so-named). They mostly inhabit wetlands and damp locations. Taxo ...

''). Other trees include such species as '' Acacia caven'' and ''

Prosopis nigra ''Prosopis nigra'' (synonym ''Prosopis algarrobilla'') is a South American leguminous tree species that inhabits the Gran Chaco ecoregion (in particular, the transition zone between the Wet Chaco and the Southern Chaco), in Argentina and Paragua ...

''. Wetlands are dominated by

aquatic vegetation Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that g ...

. Floating plants include

water hyacinth ''Pontederia crassipes'' (formerly ''Eichhornia crassipes''), commonly known as common water hyacinth is an aquatic plant native to South America, naturalized throughout the world, and often invasive outside its native range.Limnocharitaceae'', ''

Nymphoides ''Nymphoides'', or floatingheart, is a genus of aquatic flowering plants in the family Menyanthaceae. The genus name refers to their resemblance to the water lily ''Nymphaea''. ''Nymphoides'' are aquatic plants with submerged roots and floating l ...

'' and '' Ludwigia''. Another distinct zone is adjacent to the Pilcomayo River and its former channels, which are frequently flooded. It is dominated by

riparian A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks a ...

vegetation.

Figs The fig is the edible fruit of ''Ficus carica'', a species of small tree in the flowering plant family Moraceae. Native to the Mediterranean and western Asia, it has been cultivated since ancient times and is now widely grown throughout the world ...

and sweetwood trees can be found there, covered by many species of

lianas A liana is a long- stemmed, woody vine that is rooted in the soil at ground level and uses trees, as well as other means of vertical support, to climb up to the canopy in search of direct sunlight. The word ''liana'' does not refer to a t ...

vine A vine (Latin ''vīnea'' "grapevine", "vineyard", from ''vīnum'' "wine") is any plant with a growth habit of trailing or scandent (that is, climbing) stems, lianas or runners. The word ''vine'' can also refer to such stems or runners themsel ...

s and epiphytes. The patchy vegetation of the higher lands, forming distinctive "mountain islands", represent the fourth zone.

Quebracho tree Quebracho is a common name in Spanish to describe very hard (density 0.9–1.3) wood tree species. The etymology of the name derived from ''quiebrahacha'', or ''quebrar hacha'', meaning "axe-breaker". Species There are at least three similar c ...

s (''

Schinopsis balansae ''Schinopsis balansae'' is a hardwood tree known as willow-leaf red quebracho which forms forests in the subtropical Humid Chaco ecoregion of north-eastern Argentina, and Paraguay. It is also found in the wild Pantanal vegetation in Brazil. Some ...

'' and ''

Aspidosperma quebracho-blanco ''Aspidosperma quebracho-blanco'', commonly known as Quebracho blanco, kebrako, or white quebracho, is a South American tree species, native to Brazil, northern Argentina, Bolivia, Paraguay, and Uruguay. It must not be confused with other specie ...

'') can frequently be found there.

Fauna

Higher lands are inhabited by such mammals as the gray brocket, capybara,

peccary A peccary (also javelina or skunk pig) is a medium-sized, pig-like hoofed mammal of the family Tayassuidae (New World pigs). They are found throughout Central and South America, Trinidad in the Caribbean, and in the southwestern area of North ...

howler monkey Howler monkeys (genus ''Alouatta'', monotypic in subfamily Alouattinae) are the most widespread primate genus in the Neotropics and are among the largest of the platyrrhines along with the muriquis (''Brachyteles''), the spider monkeys (''Atele ...

and puma; birds include

chachalaca Chachalacas are galliform birds from the genus ''Ortalis''. These birds are found in wooded habitats in the far southern United States (Texas), Mexico, and Central and South America. They are social, can be very noisy and often remain fairly c ...

s and

rails Rail or rails may refer to: Rail transport *Rail transport and related matters *Rail (rail transport) or railway lines, the running surface of a railway Arts and media Film * ''Rails'' (film), a 1929 Italian film by Mario Camerini * ''Rail'' ( ...

. The

maned wolf The maned wolf (''Chrysocyon brachyurus'') is a large canine of South America. It is found in Argentina, Brazil, Bolivia, Peru, and Paraguay, and is almost extinct in Uruguay. Its markings resemble those of foxes, but it is neither a fox nor a w ...

can be found in the lowlands, along with such birds as the

greater rhea The greater rhea (''Rhea americana'') is a species of flightless bird native to eastern South America. Other names for the greater rhea include the grey, common, or American rhea; ema (Portuguese); or ñandú (Guaraní and Spanish). One of two sp ...

and

seriema The seriemas are the sole living members of the small bird family Cariamidae, which is also the only surviving lineage of the order Cariamiformes. Once believed to be related to cranes, they have been placed near the falcons, parrots and passerin ...

s. Aquatic environments are inhabited by storks, herons,

roseate spoonbill The roseate spoonbill (''Platalea ajaja'') is a gregarious wading bird of the ibis and spoonbill family, Threskiornithidae. It is a resident breeder in both South and North America. Taxonomy The roseate spoonbill is sometimes placed in its own ...

s and

duck Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form ...

s. There are two

caiman A caiman (also cayman as a variant spelling) is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family, the other being alligators. Caimans inhabit Mexico, Central and South America f ...

species: the broad-snouted caiman and the

yacare caiman The yacare caiman (''Caiman yacare''), also known commonly as the jacare caiman, Spanish yacaré, Paraguayan caiman, piranha caiman, red caiman, southern spectacled caiman, ''jacaré'' in Portuguese, and îakaré in Old Tupi, is a species of cai ...

. The fish population includes species from the ''

Hoplosternum ''Hoplosternum'' is a small genus of freshwater catfish in the Callichthyinae subfamily of the armored catfish family. A fossil catfish has been identified as ''Hoplosternum sp.'' from the middle Miocene in the La Venta formation, Magdalena ...

'' that can use atmospheric air and thus tolerate droughts that frequently affect shallow water bodies in the area. The snake population is represented by species such as the yellow anaconda (''

Eunectes notaeus The yellow anaconda (''Eunectes notaeus''), also known as the Paraguayan anaconda, is a boa species endemic to southern South America. It is one of the largest snakes in the world but smaller than its close relative, the green anaconda. No s ...

'') and ''

Hydrodynastes gigas ''Hydrodynastes gigas'' is a New World species of large, rear-fanged, Dipsadidae snake endemic to South America. It is commonly and alternatively known as the false water cobra and the Brazilian smooth snake.Warrell DA (2004). "Snakebites in C ...

'', a large water snake.

References

{{DEFAULTSORT:Rio Pilcomayo National Park National parks of Argentina Ramsar sites in Argentina Protected areas established in 1951 Protected areas of Formosa Province Humid Chaco