The usual number of tines is three. Ozotoceros was one of the most abundant and most widely distributed deer in South America but also was one of the least known. The pampas deer occupies a variety of open grassland habitats at low elevations. These habitats include areas temporarily inundated by fresh or estuarine waters, rolling hills, and areas with winter drought and no permanent surface water. In some places the grass is high enough to completely conceal a standing deer, but much of the original range has been modified by agriculture and other human activity.
Individuals are largely sedentary, there being no regular daily or seasonal movements.
Nocturnal activity has been reported, but if not disturbed, animals will feed at regular intervals throughout the daylight hours. If startled, an individual will freeze if protected by cover, or it will flee with a characteristic stiff-legged run or bound away with the tail curled over the back to reveal the white underside. The exact diet still is unknown, but the animals have been seen to selectively graze on new green growth and also to browse on shrubs and herbs. One population estimated to comprise 1,000 deer inhabited a 131,000-ha. The social behavior of Ozotoceros closely parallels that of Odocoileus.