Chacoan peccary is a large mammal with a pig-like appearance. This unique animal is the largest peccary species, from which it differs in a number of ways. Thus, Chacoan peccary exhibits 3 toes on its hind feet, whereas other peccaries possess only 2 toes. Then, the mouth of this animal is surrounded by white colored hairs. The ears, tail and snout are considerably longer than these of other peccary species. This species was described in 1930s, based on sub-fossil. Chacoan peccary was classified as a separate species only in 1975, becoming one of the most recently discovered large mammal species.
Populations of these mammals are scattered throughout central South America from western Paraguay and south-eastern Bolivia to northern Argentina. Chacoan peccaries are endemic to the Río de la Plata basin, where they generally occur in the flat plain of the Gran Chaco. Their native habitats are semi-arid thorn forests, savannah plains and marshes with considerably high temperatures and little rainfall.
Chacoan peccaries are highly social animals, forming small, stable social units of 2 - 10 individuals, including 4 - 5 mature animals and their young. As opposed to other chacoan species, these mammals are diurnal. They exhibit increased activity and take their daily trips in the morning. Each group has a rather large territory of up to 1,100 hectares as well as a care area of 600 hectares. Community members define and defend their home range against outsiders by scent marking, which they do through special scent glands, found on their back. Communication between conspecifics occurs by means of different sounds such as grunting and teeth chattering. As compared to other species of their genus, these animals are relatively peaceful. However, they do display some aggressive behavior such as charging and biting.
Peccaries are omnivores, but the Chacoan Peccary prefers to feed different cacti species, supplemented by acacia pods, bromeliad roots as well as fallen cacti flowers.
Little is known about the mating system and behavior of Chacoan peccaries. However, they might exhibit polygynous mating system, like other peccary species. Although Chacoan peccaries are seasonal breeders, the breeding season usually varies greatly, associated rainfall and sufficient amount of food. Females generally produce up to 4 young with an average of 2 - 3 per litter, after 5 months of gestation. They may yield offspring at any time of year, but usually do so in September-December. They often leave their herd in order to give birth. Newborn babies of this species are well-developed. During the first few hours after birth, they are capable of running. Females usually first yield offspring at 2 years old.
Listed as Endangered, Chacoan peccaries are currently facing a number of threats, which negatively impact their overall population and range. One of the biggest threats to this species is destruction of their natural habitat for cattle pastures, due to which native plants are altered with grass. As a result, these peccaries are left without suitable food and sheltering sites and are thus exposed to hunting by humans and predation. Additionally, Chacoan peccaries are threatened by diseases, carried by predators such as large felids.
There are no estimates of population numbers for Chacoan peccaries. According to the IUCN Red List resource, the population of this species in Paraguay was about 5,000 animals in the early 1990s. As reported by the same resource, the population in Argentina was estimated to approximately 3,200 individuals in 2002. Overall, Chacoan peccaries are classified as Endangered (EN) and their numbers today are decreasing.