The Giant Armadillo (Priodontes maximus) is the largest species of the Xenarthra Superorder and can reach up to 150 cm (including the tail) and weigh up to 50 kilograms. The Superorder Xenarthra is represented today by Anteaters, Sloths, and Armadillos, and can be traced back to the Early Tertiary, about 60 mya. However, although formerly abundant, nearly all the giant Xenarthra went extinct at the end of the Pleistocene. These included gigantic ground sloths which could reach over 3 meters and weigh more than 350 kilograms, or gargantuan heavily armored glyptodonts which could reach the size of a small automobile. Today, these giants are all but gone. However, almost forgotten by science, one species reminiscent of this amazing past still exists: the Giant Armadillo.
Giant Armadillos have a large, dark dorsal armor with many narrow bands. The armor is marked laterally on its edge by a distinctive lighter band that surrounds the entire carapace. Legs, tail and head are also covered with tough pentagonal scales while underneath the carapace; the bare skin is pinkish, wrinkly and unprotected. One of the most striking features of the species is the large scimitar-shaped fore claws, the third of which is greatly enlarged and can reach over 15 cm.
Although widespread, Giant Armadillos are rare over their entire distribution range. Giant Armadillos range over much of South America in 11 different countries (Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname, and Venezuela) and are found in a diversity of habitats ranging from tropical forests to open savannas. The species is distributed east from the Andes from Colombia and Venezuela, South to Paraguay and Northern Argentina. In Brazil, except in the Northeast, the species is found throughout most of the country, although it is probably extinct in the South and almost extinct in the East. The species has been registered throughout the Amazon, Atlantic Forest, Cerrado and Pantanal biomes in Brazil.
Giant Armadillos are highly fossorial and therefore rarely seen. They are nocturnal, spending the daytime period deep in their burrows. At night they come out to feed on ants and termites. They are extremely powerful diggers and their very large foraging and sleeping holes are easily recognized. These holes are often the only evidence of the species presence in an area. Although the giant armadillo is widespread geographically, it is nowhere near as common as the range maps would imply. Often only individual animals rather than populations are found in what might seem a prime habitat. The giant armadillo is threatened with extinction and is currently classified as “Vulnerable” (A2cd) by the IUCN/SSC Red List of Threatened Species (IUCN, 2010). Estimates for population declines based on habitat loss and hunting are at a level of at least 30% in the past 25 years. The species is listed on Appendix I of CITES (CITES, 2005). In Brazil, the species is classified as “Critically Endangered” in many State lists.
It appears that Giant Armadillos are naturally rare throughout their distribution and are becoming even more rare because of anthropogenic impacts. Due to their low population densities and low reproductive rates they can rapidly become locally extinct. Habitat loss and hunting are the main threats to the species. Estimates for population declines based on habitat loss and hunting are at a level of at least 30% in the past 25 years which is the main reason why the species is listed as “Vulnerable” (A2cd) by the IUCN/SSC Red List of Threatened Species (IUCN, 2010). Due to the large size of adult Giant Armadillos, these animals can be a preferred hunting target of local communities and subsistence hunters in biomes such as the Amazon. In the Cerrado the main threat is habitat loss. The small fragmented populations could also be impacted by the recent practice of poisoning termite mounds. Although difficult to quantify, it may also be targeted by collectors for its giant middle fore claw. Other impacts contributing to the decline of populations include fire and road-kill. Virtually nothing is known about the effect of infectious diseases on Giant Armadillos.
The general public does not know this species exists or when shown a picture believe it is already extinct. This should be considered a threat as the species can go extinct without anybody caring. In the Pantanal, results from our interviews also revealed that ranch workers who know of the giant armadillo believe that seeing it brings bad luck and that it must be killed if seen.
In 2010, the Giant Armadillo Conservation Program (GACP) successfully established the first long-term ecological study of Giant Armadillos in the Brazilian Pantanal.
In 2015 the project expanded activities into the highly disturbed Cerrado biome and in 2018 to the Atlantic forest. The main goal of the project is to investigate the natural history and health of Giant Armadillos, understand their function in the ecosystem, and utilize field data to inform conservation outreach and planning.
Results from the long term study in the Pantanal have advanced scientific knowledge and yielded important conservation information, including the documentation of Giant Armadillos as ecosystem engineers, new details on home range, habitat selection, diet, health and reproduction including key life parameters such inter-birth rates and sexual maturity. Giant Armadillos play an important role to the wildlife community as their burrows are used by over 70 different species. Burrows are used as a refuge against extreme temperatures. The deep excavations which can reach up to 5 meters deep maintain a constant temperature of 24°C. Many species including the southern tamandua, other armadillos, foxes, ocelots, agoutis and others seek refuge in the burrows as it can get very hot during the summer (well over 40°C). Also, in the winter, Arctic winds from the south can make temperatures drop significantly in the Pantanal. Some species such as collared peccaries or rodents and lizards can use the burrows a refuge against predators. The southern tamandua uses burrows as a nursery and leave their young in them. Other species such as tapirs or white lipped peccaries will take advantage of the sand mound in front of the burrow as a great resting spot, or species such as giant anteaters will take sand baths. Fresh roots and invertebrates offer food to many species of rodents, amphibians and lizards. Due to all this activity around the burrows they become the favorite hunting grounds for species such as ocelots and foxes. Giant Armadillos are a species few people know about or even notice when in the field, yet they play a key role in the ecosystem as ecosystem engineers.
Due to their solitary, nocturnal and fossorial habits, Giant Armadillos are rarely seen and are considered hard to capture and study in the wild. Overall, researchers have rarely attempted their capture and only a small number of individuals have been captured in previous studies with animals have been reported to occupy home ranges between 300 and 1,500 ha. A total of 32 Giant Armadillos have been captured since the project started and thanks to 12,168 locations the median adult home range area was estimated at 2,518 ha. Median adult daily displacement was 1,651 m. Home range area scales positively with daily displacement, and daily displacement scales positively with body mass. Median home range overlap between pairs was low (4%) and adult females presented exclusive home ranges among them confirming the solitary nature of the species. Our studies have shown that males displayed exploratory ranging behavior. For example, two of our known adult males visited areas 15 and 20 km away from their home ranges, to search for receptive females. Our observations indicate the species use olfactory cues (urine and feces) on the sand mounds of burrows as one of their communication strategies. Finally our work in the Pantanal highlights the importance of native vegetation for the species which selects forested areas to build their burrows as well scrub forest to forage. Median minimum densities for the species are around 7 to 8 individuals in the study area. This is about the same density that is reported for Jaguars in the Pantanal.
One of the biggest contributions of the project has been the discovery of information on the species reproduction. According to the project, Giant Armadillos only have one pup at a time that is only fully weaned when it is 10-11 months old. Gestation lasts 5 months while an interbirth rate of three years was observed. This means that population growth rates of the species are very low and the species’ populations cannot easily bounce back from impacts of anthropogenic threats. Furthermore the reproductive studies conducted by the project estimate that animals only reach sexual maturity between 6-9 years. For all these reasons Giant Armadillos can easily go locally extinct.
The Giant Armadillo Conservation Program education and outreach activities have helped disseminate project results and raised conservation awareness of the species, and helped address specific threats. In 2018, a full time educator was hired. Strategies employed include extensive use of print, radio, social media; a national awareness campaign in Brazilian Zoos; a Citizen Science component to involve local stakeholders in helping the project map the species distribution. The project has also recently developed close relationships with artists and is using art as a conservation tool. While we continue giving presentations in schools we have partnered with state authorities to train science teachers thereby multiplying our reach. We have also partnered with universities and NGOs to increase our effectiveness. Some successes include a sixty-minute documentary commissioned by the BBC and PBS aired in April 2017 in the United States and UK reaching our widest audience yet. The best measure of the project’s conservation success was the designation in 2014 of Giant Armadillos as one of five key mammal species that is used to set habitat conservation priorities in the Brazilian state of Mato Grosso do Sul (MS). The project finally reached one of its initial goals in November 2018, when the team participated in the Creation of a National Action Plan for giant anteaters and Giant Armadillos.
The GACP continues to expand and grow. Since its inception, the GACP has included a strong capacity building and training component – over a hundred Brazilian wildlife biologists and veterinarians. While the program in the Pantanal continues its decade long study of the natural history of the species, in the Cerrado of MS an intensive study enabled us to create a detailed map to inform habitat conservation measures. A new initiative is trying to eradicate a conflict between beekeepers and Giant Armadillos. Giant Armadillos are being killed by beekeepers as they destroy their beehives to consume bee larvae. We are currently creating a certification program to promote products of beekeepers that employ mitigation strategies to avoid the conflict. The program also intends to expand to the Atlantic forest in 2020 where our research shows only one remaining population.
Giant Armadillos are an incredible, prehistoric species that are key to biodiversity conservation and our dedicated team is fully committed to continue to work towards its conservation for the years to come.
