Distribution and Habitat
Distribution of the giant anteater is limited to the tropical and subtropical regions of the American continent. This species may thus be found in south Guatemala, west of the Andes, northwest Ecuador and Colombia, south Venezuela, southeast Bolivia, west Paraguay, northwest Argentina and east Uruguay, where it is probably extinct. Giant anteaters use a great variety of habitats, such as rainforests, cerrados, wetlands and deciduous forests, at different altitudes. In Brazil they occur in all biomes, from the Amazon to the southern grasslands (campos sulinos).
Following figure shows the map of the geographical distribution of Myrmecophaga tridactyla elaborated by the IUCN in 2005.
Breeding and lifespan
There is no distinct social structure among giant anteaters. They live as solitary animals most of the time, except for the brief mating encounters and for the cubs’ first six months of life, when they are carried by the females. Giant anteaters reach sexual maturity around two years and the females give birth to only one cub per year. There is no conspicuous sexual dimorphism. Breeding potential is low, due to the long gestation period (190 days) and the long interval between births. Nevertheless, in areas with few individuals, available food and space, and with impact factors reduced or absent, there is a potential for population increase. The species’ lifespan in the wild is not known, but Brazilian zoos report animals over 25 years old.
Home range varies a lot among regions. Studies indicate a home range of 2500 ha in Venezuela; 367 ha for females and 274 ha for males at Serra da Canastra National Park; and 693 ha for females and 1098 ha for males at Emas National Park. Studies in southern Pantanal yielded a larger home range for the female, around 1190 ha, and 570 ha for males. In this species, home range overlap occurs widely.
Little is known of this species’ diet in its natural environment. Studies have shown that giant anteaters consume a much greater proportion of ants than of termites in certain areas and periods. Ant genera more frequent in the diet are Solenopsis, Camponotus, Azteca, Crematogaster and Odontomachus, while more common termite genera are Nasutitermes, Armitermes, Velocitermes, Diversitermes, Cornitermes and Cortariterme. There is no record of predation on ants of the genus Atta. Feeding strategy is based on several very short feeding bouts; it is thought that these animals do not exhaust individual ant or termite colonies they feed upon. As a result, each giant anteater must visit several feeding sites daily.
The giant anteater (Myrmecophaga tridactyla) is considered a vulnerable species in Brazil according to the Official List of Threatened Species, as a Near Threatened species by the IUCN Red List of Threatened Species – 2005, and is also included in the Apendix II of the Convention on International Trade Endangered Species of Wild Fauna and Flora (CITES) since 2003.
Although occurring in several biomes of Central and South America, giant anteaters inhabit especially Cerrado, which once covered 28% of Brazil.
Even though it can still be found in a variety of habitats, from forests to fields, the giant anteater has suffered heavy impacts mainly resulting from the expansion of agriculture and urbanization (man-made fires, roadkills and habitat change), from occupation and accelerated development of the country’s central region, and from dog attacks (hunting pressure and predation).
The low metabolic rate, low body temperature (around 33°C), low thermoregulation capacity, small breeding potential, prolonged parental care and long gestation periods of the giant anteater are all indicators of the low intrinsic population growth rates, which renders this species quite vulnerable to anthropic pressure.
The intense exploitation of natural resources hinders natural renewal. The loss, degradation and fragmentation of habitats resulting from human activity pose the greatest threat to terrestrial mammals.
Economic development tends to increase human population density, multiplying the extrinsic factors leading to the decline of other mammal populations. In turn, the immediate impact from environmental degradation generates loss of biodiversity, threatening more species with extinction.
In the 1990s, the rapid change of central Brazil’s landscape into soy and sugar cane plantations drastically transformed the Cerrado regions, putting pressure on the wild populations through habitat decrease, man-made fires, roadkills and other factors.
In this context, several factors may contribute to the decline of giant anteater populations, including probable changes in ant and termite communities, roadkills, man-made fires and predatory hunting, among others.
In the Campos Gerais region, Paraná State, giant anteaters are commonly killed by motor vehicles, and are cited in some localities as one of the animals most affected by road kills. In view of the apparent low population density of the species throughout its entire Paraná State range, this constitutes a cause of great concern.
Many researchers state the giant anteater is the large mammal most affected by man-made fires. Due to its easily flammable long hairs and to its low mobility, giant anteaters are frequently killed in large forest fires. This is an important impact factor over small populations in Central Brazil.
Some authors suggest that along the giant anteater’s original distribution, hunting has been one of the factors responsible for population decline. In the North and Northeast regions, the animal is killed for food, for its pelt and various other ends. In other areas of Brazil, chase and killing of giant anteaters seem to be more related to attack by domestic dogs.
Giant anteaters are commonly attacked by the dogs of rural landowners who live around preservation units. This threat exists throughout the species’ entire range in Brazil. Reports of dog attacks on anteaters, as well as of anteaters killed for having attacked dogs, are quite common in rural areas.
Many threats to the conservation of the giant anteater have been identified, such as habitat loss and fragmentation, direct mortality due to large man-made fires, road kills, deliberate hunting and death associated to conflicts with dogs. However, infectious diseases play a great role in biodiversity conservation, as they may push several wildlife species to the endangered animals list. Environmental disturbances may generate greater population densities, favoring direct transmission of diseases or even increasing stress by enhancing competition and reducing food, rendering individuals more susceptible to disease.