The Uruguayan savanna is a subtropical grassland and savanna ecoregion that extends from the extreme southern part of the Rio Grande do Sul, a Brazilian state, to include the entire country of Uruguay and a small section of the Argentinean province of Entre Ríos.
The Uruguayan savanna, also known as the Brazilian-Uruguayan savanna, is a subtropical grassland and savanna ecoregion that extends from the extreme southern part of the Rio Grande do Sul, a Brazilian state, to include the entire country of Uruguay and a small section of the Argentinean province of Entre Ríos.
Consisting mostly of medium-tall grasslands, these savannas encompass a mosaic of gallery forests, palm savannas and outcropping of submontane forests. The gallery forests are found along the Uruguay, Negro, Yaguarí, Queguay and Tacuarembo Rivers in the easternmost part of the ecoregion, while submontane forests and palm savannas are scattered throughout the ecoregion.
The complex geology of the ecoregion includes precambric, cretaceous and jurassic rocks, as well as more recent sedimentary rocks. Two-million year old metamorphic and magmatic rocks are predominant in the eastern side of the ecoregion. There is a two-hundred-kilometer-wide strip from the coastal area to the northern part of the ecoregion containing six-million year old metamorphic rocks.
Seventy-two species of mammals occur in this ecoregion including four marsupials, seventeen chiropterans, five xenarthrans, seventeen carnivores, two artiodactyls, and twenty rodents. Some of the native mammals in the savannas are the pampas deer (Ozotoceros bezoarticus), Guazauvirá deer (Mazama gouazoubira) and capybara (Hydrochoerus hydrochaeris).
Most of the mammals from this ecoregion are found in the gallery forests along the Uruguay River and in the small ravines of the north. The majority of the avian fauna (400 species) is concentrated in wetlands. Only 80 species of birds inhabit the savannas.
The savannas are critically endangered due to the fact that there are few small isolated patches of intact habitat remaining. The whole ecoregion has been severely altered by cattle ranching, one of the main pillars of the national economy in Uruguay.