The marsh deer (''Blastocerus dichotomus'') is the largest

deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the re ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

from

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

reaching a length of and a shoulder height of . It is found in

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

, Bolivia,

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

and

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 ...

. Formerly found in much of tropical and subtropical South America, it ranged east 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 ...

, south from the Amazon rainforest, west of the Brazilian Atlantic rainforest and north of the Argentinian Pampa. Today it is largely reduced to isolated populations at marsh and lagoon zones in the Paraná,

, Araguaia and Guapore river basins. Small populations also occur in the southern Amazon, including Peru where protected in Bahuaja-Sonene National Park.Thornback, J., and M. Jenkins. 1982. The IUCN mammal red data book, Part 1: Threatened mammalian taxa of the Americas and the Australian zoogeographic region (excluding Cetacea). IUCN. 516 pp.Cabrera, A. 1961. Catalogo de los mamiferos de America del Sur. Rev Mus Argentino Cien Nat Bernardino Rivadavia. 4:1-732.Tomas, W.M., M. Beccaceci, and L. Pinder. 1997. Cervo-do-pantanal (Blastocerus dichotomus). Biologia e Conservacao de Cervideos Sul Americanos. 24-38. It is listed as a

vulnerable species A vulnerable species is a species which has been categorized by the International Union for Conservation of Nature as being threatened with extinction unless the circumstances that are threatening its survival and reproduction improve. Vulnera ...

by the IUCN and is protected under

CITES Appendix I CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of intern ...

. Ths is the only species in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''Blastocerus''. The latter half of its scientific name refers to the forked antlers. Marsh deer resemble the North American

mule deer The mule deer (''Odocoileus hemionus'') is a deer indigenous to western North America; it is named for its ears, which are large like those of the mule. Two subspecies of mule deer are grouped into the black-tailed deer. Unlike the related whi ...

blacktail deer Two forms of black-tailed deer or blacktail deer that occupy coastal woodlands in the Pacific Northwest of North America are subspecies of the mule deer (''Odocoileus hemionus''). They have sometimes been treated as a species, but virtually all ...

Description

They possess very large ears lined with white hairs, red-gold to tawny brown fur, blackish eyes and long dark legs. The hair turns darker during winter. There are also white marks on the hips and around the eyes. The legs are black below the tarsal as is the muzzle. The

tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...

is of a paler reddish tone than the rest of the body on its upper part and black on the under part. The head-and-body length is , while the tail adds a further . The height at the shoulder can range from . The

hoof The hoof (plural: hooves) is the tip of a toe of an ungulate mammal, which is covered and strengthened with a thick and horny keratin covering. Artiodactyls are even-toed ungulates, species whose feet have an even number of digits, yet the rum ...

, which is large in relation to the body, has elastic interdigital membranes which are useful for swimming and walking on marshy surfaces. Only the males possess antlers which are ramified and reach a length of 60 cm (23 inches). An adult typically grows to a weight of , although an occasional big male can weigh up to .

Ecology and behavior

They are solitary animals or living in groups with less than 6 individuals with only an adult male. Their main predators are the jaguar and the puma.

Habitat

The marsh deer lives only in marsh areas, notably the

Pantanal The Pantanal () is a natural region encompassing the world's largest tropical wetland area, and the world's largest flooded grasslands. It is located mostly within the Brazilian state of Mato Grosso do Sul, but it extends into Mato Grosso and ...

and Chaco, in which the level of water is less than deep. They are swift swimmers. The marshes with their high vegetation density protect them from

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

s and provide them with food. These deer also have a small migratory pattern, they follow the water levels between the dry season and flooding season. With the fluctuation in water levels, they are able to find new food sources that the water uncovers during the dry season. Some freshwater ponds on the Pantanal Wetland, Brazil reported low densities of individuals dictating that those ponds are not able to support large populations of marsh deer.Tomas, W.M., S.M. Salis, M.P. Silva, and G.M. Mourao. 2001. Marsh deer (Blastocerus dichotomus) distribution as a function of floods in the Pantanal Wetland, Brazil. Studies on Neotropical Fauna & Environment. 56:9-13.

Diet

Since marsh deer live near aquatic habitats, they eat a majority of their diet in aquatic plants. A study was conducted and they found 40 different species of plants in which they ate. The main food component was Graminae which took up 22% of their diet,

Pontederiaceae Pontederiaceae is a family of flowering plants. The APG IV system of 2016 (unchanged from the APG III system of 2009, the APG II system of 2003 and the APG system of 1998) places the family in the order Commelinales, in the commelinid clade, ...

took up 12%, Leguminosae was about 11%, and the rest was filled in with Nymphaeaceae,

Alismataceae The water-plantains (Alismataceae) are a family of flowering plants, comprising 19 genera (17 extant and 2 fossil) and 117 species. The family has a cosmopolitan distribution, with the greatest number of species in temperate regions of the Northe ...

Marantaceae The Marantaceae are a family, the arrowroot family, of flowering plants consisting of 31 genera and around 530 species, defining it as one of the most species-rich families in its order.Kennedy, H. (2000). “Diversification in pollination mechan ...

Onagraceae The Onagraceae are a family of flowering plants known as the willowherb family or evening primrose family. They include about 650 species of herbs, shrubs, and treesCyperaceae. They also enjoy eating aquatic flowers and shrubs that grow in the swamps and the floating mats.Tomas, W.M., and S.M. Salis. 2000. Diet of the marsh deer (Blastocerus dichotomus) in the Pantanal wetland, Brazil. Studies on Neotropical Fauna & Environment. 35:165–172. They can be best classed as a grazer-browser for food. Their diet also changes between the dry season and the flood season.

Reproduction

Usually the rutting season coincides with the dry season but can change from animal to animal. They may use this to their advantage for breeding or finding mates because the densities of marsh deer are significantly higher on the Rio Negro marshland boundary during the dry season compared to the less dense, more distributed population during the flooded season. Gestation lasts approximately 271 days. The offspring (normally one per female, though occasionally twins are born) are born between October and November. The infant deer are whitish which becomes more adult-like after a year.

Conservation

The natural predators of the marsh deer – the jaguar (locally called onça or yaguaraté) (''Panthera onca'') and the puma (''Puma concolor'')— have almost completely disappeared from its habitat. The former major threat was poaching for its antlers, but this is somewhat under control. Destruction of its habitat presents nowadays the major threat to marsh deer. The Yacyretá Dam altered an area in which several hundred individuals lived and the draining of marshes for farmland and cattle farming threaten hundreds of hectares every year in Argentina and Brazil. Contagious diseases from cattle are also a problem, though it has been shown that the deer is not affected by

brucellosis Brucellosis is a highly contagious zoonosis caused by ingestion of unpasteurized milk or undercooked meat from infected animals, or close contact with their secretions. It is also known as undulant fever, Malta fever, and Mediterranean fever. The ...

. In October 2018, Argentina established the Ciervo de los Pantanos National Park to help protect this species.

References

External links

* * {{Taxonbar, from=Q504501 Capreolinae Mammals of Argentina Mammals of Bolivia Mammals of Brazil Mammals of Paraguay Mammals of Uruguay Fauna of the Pantanal Mammals described in 1815