Marsh Deer

Returning the greatest cervid of the country

The marsh deer (Blastocerus dichotomus) is the largest deer of South America, and can reach 150 kg. They are generally solitary animals and the females give birth only once a year a fawn which remains with its mother for about a year. The marsh deer feeds on typical vegetation of marshy environments and their surroundings. It inhabits floodplains, vegetated lagoons, estuaries with floating vegetation, flooded plains and other tropical and subtropical marshes.

The loss of their populations in the region

Worldwide the marsh deer is categorized as Vulnerable as in Argentina. Historically, the species was distributed in a large region of central South America. At present, the populations are reduced to the center-east and northeast of Argentina, center-west and south of Brazil, Paraguay, southeast of Peru and eastern Bolivia, while it has been extinct in Uruguay. In Argentina there are isolated population centers on floodplains along the Paraná and Paraguay rivers and areas of influence. The most important nucleus is found in the Iberá wetlands in Corrientes, where the population has recovered during the last decades, with a total of 8,900 individuals estimated between 2006 and 2008. Likewise, there are smaller populations in the Paraná River Delta, in the provinces of Buenos Aires and Entre Ríos, Formosa, Chaco and Santa Fe.

The historical distribution of the largest Argentine deer

In Argentina, the species was distributed in the provinces of Misiones, Corrientes, Entre Ríos, Santa Fe, Formosa, Chaco, Buenos Aires, Salta and Jujuy. In addition, there are numerous references of travelers who have sighted this species along the streams of the Bermejo and Bermejito rivers, both in the province of Chaco and in Salta. There are numerous citations of the presence of the species in the vicinity of the Impenetrable National Park, where it is possible that the species has disappeared due to direct hunting and competition with livestock and diseases transmitted by it.

The Impenetrable is the largest national park in the north of Argentina and shelters one of the best-preserved samples of the dry Chaco. Although the majority of the species that inhabited this park reduced their numbers in the past, the effect was more noticeable in the grasslands and in the wetlands, in which the great herbivores of these environments disappeared, including the marsh deer. The creation of this park opens a great opportunity to restore degraded environments and populations of extinct species in this protected area.

The role of the species in the ecosystem

The marsh deer, one of the native herbivores of greater size adapted to marshy environments, plays a fundamental role in the ecosystem. The restoration of their populations will be a first step to return to the Impenetrable the integrity and ecological functionality of the Dry Chaco, so that it recovers its evolutionary and ecological processes and returns to efficiently provide the environmental services that were its own.

The first experience of translocation between National Parks of Argentina

CLT proposed the reintroduction of the marsh deer in El Impenetrable National Park through the translocation of wild individuals from the Iberá Park population. The latter represents the most important population of the country, so it can serve as a source of animals to found a new population without generating a significant impact on it. This proposal would represent the first experience of reintroducing the species in Argentina, setting precedents for similar future actions throughout its range of distribution in our country. It will also generate a unique opportunity for interprovincial and interjurisdictional collaboration and will open the way for new projects in the field of wildlife reintroductions and translocations in National Parks and other natural reserves throughout the country.