Uruguay, situated on the southeastern coast of South America, is bordered by Brazil to the north and Argentina to the west, with its southern and eastern edges meeting the Río de la Plata estuary and the Atlantic Ocean. The country’s landscape is dominated by gently rolling plains and low-lying hills, which are characteristic of the Pampas biome. An extensive coastline and major river systems like the Uruguay River and the Río Negro create distinct zones of biodiversity. These geographical features define the habitats for a variety of fauna, from grazing mammals on the open plains to specialized marine life in the temperate Atlantic waters.
Terrestrial Life of the Pampas Grasslands
The vast grasslands of the Pampas characterize the majority of Uruguay’s inland territory, providing a habitat for species adapted to life on the plains. One of the largest native grazers is the Pampas Deer (Ozotoceros bezoarticus), a slender mammal that relies on speed and camouflage among the tall grasses to evade predators. This species holds a protected status, having been declared a Natural Monument to aid in its conservation.
Sharing the landscape is the Greater Rhea (Rhea americana), the largest native bird in the region. This flightless species moves rapidly across the plains and is often seen in small groups. They exhibit a unique mating system where the male incubates the eggs and raises the young. The Pampas Fox (Lycalopex gymnocercus) is a common predator, utilizing its adaptability to hunt rodents and small animals throughout the grassland and agricultural areas.
Armadillos, known for their bony armor shells, are also a distinctive part of this ecosystem, with species like the Six-banded Armadillo (Euphractus sexcinctus) frequently rooting in the soil for insects and other small invertebrates. Their burrowing activity is an important function in the soil ecology of the Pampas. These species thrive away from water, relying on the extensive grass cover for sustenance and shelter.
Coastal and Marine Habitats
Uruguay’s eastern edge features a dynamic coastal environment where the freshwater outflow of the Río de la Plata meets the temperate waters of the Atlantic Ocean. This confluence, influenced by the Brazil and Malvinas ocean currents, creates a highly productive marine ecosystem. The coastline is renowned for its large colonies of pinnipeds, notably the South American Sea Lion (Otaria flavescens) and the South American Fur Seal (Arctocephalus australis).
Protected islands, such as Isla de Lobos, serve as significant breeding grounds for these seal and sea lion populations, supporting thousands of individuals. These animals forage widely in the productive shelf waters, feeding on fish and squid. The coastal waters are also home to the Franciscana Dolphin (Pontoporia blainvillei), a small, endemic species recognizable by its long, slender snout.
Larger migratory marine mammals utilize the Uruguayan coast, with the Southern Right Whale (Eubalaena australis) passing through during its annual migration. These whales use the productive waters as a calving and nursing ground during the winter and spring months. Coastal lagoons and beaches attract numerous migratory bird species, including gulls and terns, along with occasional visitors like penguins that venture north from sub-Antarctic waters.
Riverine and Wetland Ecosystems
The inland river systems and extensive freshwater wetlands, such as the Bañados del Este, provide specialized habitats for semi-aquatic fauna. The Capybara (Hydrochoerus hydrochaeris), the world’s largest rodent, is abundant, often seen in social groups grazing on aquatic plants and grasses along the riverbanks. Its semi-aquatic nature allows it to evade predators by submerging itself, utilizing its webbed feet for swimming.
Reptiles are represented by the Broad-snouted Caiman (Caiman latirostris), a species of alligator found in the marshes and slow-moving waters of the northeastern wetlands. The Caiman is an apex predator, preying on fish, amphibians, and small mammals. The extensive network of rivers, including the Uruguay and Río Negro, supports a rich diversity of freshwater fish.
One notable fish is the Golden Dorado (Salminus brasiliensis), a large, powerful predator prized for its distinctive golden color, which migrates upriver to spawn. The wetlands are also a haven for a multitude of waterfowl and wading birds, including:
- The elegant Black-necked Swan.
- Various species of storks.
- Herons.
- Ibises.
These birds rely on the marshy areas for feeding and nesting, making the wetlands a major avian biodiversity center.