The marsh deer lives in the grasslands that exist along the southern fringe of the Amazon Basin. This habitat begins in southern Peru and Brazil and extends into northern Argentina, deer once lived in Uruguay, but it is now thought to be extinct there.
Marsh deer browse on a range of plants that grow in waterlogged environments. They inhabit the small areas of swamp and bog that exist all year around. However, many of the grasslands in their range become flooded in the wet season, enabling the deer to disperse over a wider area. They are most active in the half-light of dawn and dusk, although they are sometimes also seen feeding during the day and at night.
The marsh deer is the largest deer in South America. It has wide feet with an elastic layer of skin between the hooves. This makes the foot webbed, and prevents the heavy deer from sinking into mud and other soft ground. The long, coarse coat is a reddish-brown in summer, turning to a darker brown in winter. There are white rings around the eyes.
Marsh deer generally live alone during floods, but form small groups of about five deer when they gather around water sources in dry periods. Males occupy a home range that covers those of several females. The males rut in October and November to establish their dominance. The ranking established by the rut is maintained throughout the year.
Distribution: South America, from southern Peru and Brazil to Paraguay and northern Argentina. Now presumed extinct in Uruguay.
Habitat: Marshy areas in grasslands.
Food: Grass, leaves and aquatic plants.
Size: 1.5 - 2 m (5 - 6.5 ft); 89 - 125 kg (195 - 275 lb). Height at shoulder 1 - 1.2 m (3.25 - 4 ft).
Maturity: 2 years.
Breeding: Single fawn produced in summer; gestation is about 9 months.
Life span: 10 years.