Armadillos

(Dasypodidae)

Class Mammalia

Order Xenarthra

Family Dasypodidae

Thumbnail description
Small to medium-sized omnivore or insectivore with homodont teeth and a tough carapace covering portions of the back, face, tail and legs; sparse hairs cover soft underside; elongated or shovel-shaped head has small eyes and ears and powerful legs have large claws for digging

Size
Head-to-tail length: 6–59 in (0.15–1.5 m); weight: 0.18–66 lb (0.08–30 kg)

Number of genera, species
8 genera; 20 species

Habitat
Forest (deciduous, cloud, and rain), savanna, pampas, desert, and scrub

Conservation status
Endangered: 1 species; Vulnerable: 5 species; Lower Risk/Near Threatened: 2 species; Data Deficient: 4 species

Distribution
Latin America with one species ranging into southern North America

Evolution and systematics

Fossil armadillos found in South America are considered the oldest members of this order. During the Tertiary Period, they diversified in South America when it was isolated from the north. After the land bridge formed, armadillos invaded North America but became extinct there only 10,000-15,000 years ago. These invaders included giant herbivorous armadillos (pampatheres) and those resembling armadillos living today. Also present were rhinoceros-sized glyptodonts with solidly sutured carapaces without movable banding that may have had limited locomotion. Spines or club-like structures on the end of their tails were used for deterring predators or fighting other glyptodonts. These clubs could exert a force that could have caused fractures observed on fossil carapaces. Since the mid-nineteenth century, the nine-banded armadillo (Dasypus novemcinctus) has reinvaded North America, expanding its range into the southeastern United States. Similarities observed between living armadillos and their ancestors led Charles Darwin to develop the law of the succession (i.e., the same types of organisms replace one another within the same area), an adjunct to descent with modification.

Some phylogenies based on molecular data have used armadillos to place xenarthrans as a sister taxon to ferungulates (carnivores and hoofed mammals), whereas others place them with Afrotheria (elephants, hyraxes, and aardvarks). The armadillo suborder, Cingulata, split from anteaters and sloths around the Cretaceous/Tertiary boundary. Cingulata has only one living family, Dasypodidae, which has three main clades represented by the subfamilies: Dasypodinae, the long-nosed genus that arose first, Tolypeutinae (giant, naked-tailed, and three-banded armadillos), and the closely related Euphractinae (hairy, yellow, and pichi armadillos). Phylogeny within the subfamilies remains unclear. The genus, Chlamyphorus, does not appear in the analysis because populations were rare and not sampled.

Physical characteristics

The Spanish word armadillo means "little armored one." Armadillos are quite unique in that they are the last mammals to have a shell, that is, an ossification of the corium interrupted by several folds of the skin. The surface of the skin is gray or brown, quite soft and feels like leather. Thanks to the skin folds, the animal is very agile. Surprisingly stocky and low to the ground, armadillos are medium-sized mammals with extra articulating structures in the vertebral column that presumably improve digging. Armadillos are named for the tough bony carapace that covers the pelvic and pectoral girdles as well as areas on the head, limbs, and portions of the tail. Made of ossified dermal tissue covered with a horny epidermis, the carapace, ranging in color from dark to yellow-white, provides protection from thorny vegetation, conspecifics and predators. When harassed, armadillos will tuck their eyes under the shoulder shield and coil slightly to minimize the amount of exposed flesh. Three-banded armadillos (Tolypeutes) take this to the extreme and bend completely into a ball, exposing only thick carapace. Girdle-like armor banding (3–13) separated by

folds of skin provides flexibility and agility in locomotion. Black to white-colored hairs may be interspersed on the cara-pace and cover their soft underbellies.

The head varies from shovel-shaped to elongated and narrow. The ears vary in length as well and can be pointed or rounded. Powerful limbs bear formidable claws for digging burrows and gathering food. Hind limbs always have five digits while the number of forelimb digits varies (three to five) depending on the species. Naked-tailed (Cabassous) and giant armadillos (Priodontes maximus) possess an enlarged claw on the forelimb used to tear into termite and ant mounds. Wielding this large claw and rotating their carapaces back and forth enable these armadillos to escape predators by burying themselves within minutes.

Distribution

Most armadillos are restricted to South America, specifically east of the Andes to the Atlantic coast and south to the

Strait of Magellan. Exceptions include the northern naked-tailed (C. centralis) and the nine-banded armadillos that have expanded their ranges into southern Mexico and the southeastern United States, respectively.

Habitat

Armadillos are terrestrial to fossorial, exploiting habitats ranging from rainforests to desert, including deciduous and cloud forests, grasslands, llanos, savanna, and thorny scrub. In tropical rainforests armadillos are second only to sloths in mammalian biomass. Adult armadillos are prey to jaguars, pumas, jaguarundis, wild dogs, maned wolves, black bears, and alligators. Probably due to their smaller size, nine-banded armadillo juveniles have twice the mortality of adults, falling prey to these and other animals including raptors.

Burrows, built for sleeping, nesting, escaping predators, or creating an insect reservoir, are dug in well-drained soils or into ant and termite mounds. Naked-tailed armadillos dig a fresh burrow nightly while nine-banded armadillos may reuse 20 burrows per year. In some species, adults and juveniles build nests in burrows by gathering and tucking grass or dead leaves between body and forelimbs, hopping backwards to the burrow, and depositing material by kicking their back feet. Female larger hairy (Chaetophractus villosus), nine-banded and Brazilian seven-banded (D. septemcinctus) armadillos construct above ground grass shelters prior to parturition.

Behavior

Armadillos are primarily solitary though young siblings and consorting pairs forage together. Llanos long-nosed armadillos (D. sabanicola) have been seen feeding in groups in elevated areas in floodplains. Social organization for most species is unknown with the exception of nine-banded armadillos. In this species, males and females have overlapping

home ranges. Females may or may not share an area with each-other depending on density. Although males do overlap in home range, breeding males may use more exclusive areas. These breeding "territories" are maintained by aggression directed at non-breeding males. Female aggression in nine-banded, yellow (Euphractus sexcinctus), and larger hairy armadillos is associated with lactation. Defense of space was also seen in northern long-nosed armadillos during the breeding season.

These animals communicate through scent and sound. Secretions from glands in the anal region, on the feet, ears, and pelvic shield function for marking of habitat, identifying individuals, and advertising sexual receptivity. Chemical composition of anal sac glands changes during estrus in nine-banded armadillos and paired females conspicuously wag their tails after male solicitation. The position of large smelly glands on the yellow armadillos pelvic shield suggests a burrow-marking function. Armadillos give off a snuffling sound while foraging and some make a growling sound or a scream when captured. Both sexes in nine-banded armadillos softly chuck during courtship. A buzzing sound may be heard between mother and young. Strangely, armadillos seem unaffected by human voice. Eyesight is so poor that they may run into objects in their path.

Activity is mostly crepuscular and/or nocturnal although yellow, three-banded, northern long-nosed, and pichi (Zaedyus pichiy) armadillos forage during the day. Many species shift activity periods seasonally, becoming more diurnal as temperatures drop. Only Andean hairy (C. nationi) and pichi armadillos hibernate. Young nine-banded armadillos have a morning and an evening peak of activity. When active, armadillos mostly forage. When disturbed, many balance on back feet and tail and sniff to monitor for predators or conspecifics. If suddenly surprised, nine-banded armadillos will leap into the air and land running, startling a predator. This escape strategy is used unsuccessfully with automobiles, resulting in road kills. Armadillos are champion sleepers, spending upwards of 16 hours snoozing per day.

Feeding ecology and diet

Armadillos are primarily insectivores, feeding on adult and larval forms of beetles, ants, and termites. Some species are myrmecophagic while others opportunistically forage on invertebrates, small vertebrates, carrion, and plant material. Some ingest fruit seasonally. Armadillos ingest large amounts of dirt for mammals. It is unknown whether dirt is required for proper digestion or trace minerals or enters the gut incidentally with food.

Armadillos root around in leaf litter and pause periodically perhaps to sense soil-dwelling prey. Once prey is detected, armadillos use their formidable claws to dig rapidly, excavating small conical pits or tearing into ant and termite mounds. Their sticky tongues effectively lap up the scurrying insects. One stomach had more than 40,000 ants present. Armadillos have a very low metabolic rate, which means that they do not waste a lot of energy producing heat. This also means that they are not good at living in cold areas, because they are not efficient at keeping warm. They do not have any fat reserves, so they must forage for food on a daily basis. A few consecutive cold days can be deadly to the animals.

Reproductive biology

Mating for most species appears to be polygynous and occurs in the summer but some species breed year round in captivity. During courtship, a male follows the female and, for nine-banded armadillos, they forage together for several days. The male checks receptivity by soliciting the female to lift her tail by lightly touching her back. Fertilization occurs but implantation of the embryo is delayed for four months in some species. Most species have a litter of one to three young per year. Unique to mammals, Dasypus females exhibit obligate polyembryony, thereby giving birth to genetically identical young (two to 12 depending on the species). Parental care is solely the job of the female. Mating systems are unknown for most species except nine-banded armadillos. Gestation is 140 days, newborn are blind and naked with soft leathery skin, that hardens into armor within a few days. The young are nursed for 2–2.5 months, and start to walk around after a week and open their eyes after 3–4 weeks.

Conservation status

Of the 20 species of armadillos, 12 are listed as Vulnerable, Endangered, Near Threatened, or Data Deficient. Exploitation for food and loss of habitat are the main reasons for decline. Many populations are fossorial and have not been studied thoroughly and so their current status is unclear. The hairy long-nosed armadillo (D. pilosus) is known only from a few skins from mountains in Peru.

Significance to humans

Armadillos are exploited throughout Latin America for food. They are considered so tasty that one Mexican society circumvented food taboos by calling them turkeys. In the

United States during the Great Depression in the thirties, armadillos were readily consumed and given the names Texas turkey and Hoover hog. Souvenir purses and baskets with tail handles are formed from hollowed-out carapaces. Stuffed specimens on tip toes still line shop shelves in Mexican border towns. Armadillos are unwanted guests in suburban settings and agricultural fields. Ranchers have also targeted armadillos for extermination because their burrows report-edly lead to broken limbs of livestock and horses. Many change their minds upon hearing that armadillos are the only known predator of fire ants in the United States. Armadillos also are used as research models in the study of leprosy and development of a vaccine, because they are the only animals that can transmit leprosy.

Species accounts

List of Species

Nine-banded armadillo

Dasypus novemcinctus

subfamily

Dasypodinae

taxonomy

Dasypus novemcinctus Linnaeus, 1758, Brazil.

other common names

English: Common long-nosed armadillo; French: Tatou à neuf bandes; German: Neunbinden-Gürteltier; Spanish: Mulita.

physical characteristics

Length 25.4 in (64.6 cm); weight 9.9 lb (4.5 kg). Dentition: 7–9/7–9. Has 7–9 bands, a long banded tail, an elongated face, and large ears held close together.

distribution

Latin America, southern North America.

habitat

Forested areas preferred.

behavior

Crepuscular and nocturnal but more diurnal during the winter. Solitary. Prescribed home ranges maintained. Male breeding territories suggested. Polygynous. Can go without oxygen for short periods while foraging in soil. Walks across the bottom of small streams but gulps air and dogpaddles across larger bodies of water. Armadillos are fond of water; under arid, dry climatic conditions, they concentrate in the vicinity of streams and water holes. Tracks in the mud around small ponds give evidence that the armadillos visit them not only for purposes of drinking and feeding, but also to take mud baths. Armadillos are timid animals. They are almost constantly active when foraging and probing into crevices and under litter for food. They continuously grunt while foraging and do not seem to be particularly attentive to their surroundings. They communicate with each other by low-volume sounds.

feeding ecology and diet

Eats beetles, beetle larvae, ant larvae, other insects and invertebrates, small vertebrates, and fruit seasonally. Moves noisily through leaf litter stopping periodically to probe the soil.

reproductive biology

Polygynous mating occurs in summer months, June though August in the United States. Courtship may last several days. Implantation of embryo is delayed for four months or as long as two years. Gestation lasts four months with births occurring about 65 days after implantation. Females exhibit polyembryony, giving birth to four genetically identical young. Not all individuals breed in a given year. In one population, genetic studies showed only one third of adults were parents over a four-year period. Ovulation is inhibited during drought conditions.

conservation status

Not threatened.

significance to humans

Used as food and as an animal model for penile erection and leprosy studies.

Small hairy armadillo

Chaetophractus vellerosus

subfamily

Euphractinae

taxonomy

Dasypus vellerosus (Gray, 1865), Bolivia.

other common names

English: Small screaming armadillo; French: Petit tatou velu; German: Weisshaar-Gürteltier; Spanish: Quirquincho chico.

physical characteristics

Length 14.6 in (37 cm); weight 1.9 lb (850 g). Dentition: 9/10. Smallest of the hairy armadillos, it has a broad head shield with widely spaced ears and 18 bands. Silky hairs sparsely cover the body. Kidneys concentrate fluids and are thus adapted to arid climates.

distribution

Bolivia, Paraguay, and Argentina.

habitat

Sandy desert habitat that is not rocky.

behavior

Fossorial and nocturnal to avoid the day's heat but become more diurnal in the winter. Spend most of their time foraging near vegetation in prescribed home ranges (4.7 ha on average). In captivity, forages systematically, spiraling inwardly in a patch. Multiple burrows, found in sand dunes or near vegetation, are used for resting, shelter and foraging. Gives off an eerie scream when handled.

feeding ecology and diet

Omnivorous diet consists of invertebrates, vertebrates and plant material. Summer diet includes rodents (20%). Diet adapted to desert life where insects are scarce.

reproductive biology

Captive animals give birth to one to two young and have a gestation period of 65 days. Probably polygynous.

conservation status

Not threatened.

significance to humans

None known.

Yellow armadillo

Euphractus sexcinctus

subfamily

Euphractinae

taxonomy

Dasypus sexcinctus (Linnaeus, 1758), Brazil.

other common names

English: Six-banded armadillo; French: Tatou à six bandes; German: Sechsbinden-Gürteltier; Spanish: Gualacate.

physical characteristics

Length 24.3 in (61.6 cm); weight 9.9 lb (4.5 kg). Dentition: 9/10 or 8/9. Has a yellowish carapace with long light hairs, a broad face shield with small separated ears, and a pelvic shield with 2-4 holes secreting scent.

distribution

Suriname, Brazil, Uruguay, Paraguay, and parts of Argentina.

habitat

Inhabits savanna, steppe and forest edge.

behavior

Diurnal. Reuses burrows probably marking them with pelvic-shield glands. Unusual in that they bite when handled.

feeding ecology and diet

Omnivorous, feeding on plant material, invertebrates and vertebrates including carrion. Four rodents were found in stomach of one road kill.

reproductive biology

Females give birth to one to three young of mixed sex per litter. Does not exhibit polyembryony. In captivity gestation length is 60–65 days. May be polygynous.

conservation status

Not threatened.

significance to humans

Used as food.

Southern three-banded armadillo

Tolypeutes matacus

subfamily

Tolypeutinae

taxonomy

Loricatus matacus (Desmarest, 1804), Argentina.

other common names

French: Tatou à trios bandes du Sud; German: Kugel Gürteltier; Spanish: Bolita.

physical characteristics

Length 12.4 in (31.4 cm); weight 2.4 lb (1.1 kg). Dentition: 9/9. Three bands. Thick carapace. Short tail. Walks on tips of claws on forelimb.

distribution

Argentina, Bolivia, Brazil, and Paraguay.

habitat

Grassland and open plains.

behavior

When threatened, rolls up into a ball, exposing only its cara-pace and tail and head shields. Diurnal. Does not dig burrows but uses those built by other species. Individuals found sleeping together in winter (also the breeding season).

feeding ecology and diet

Feeds on ants and termites obtained by digging shallow pits.

reproductive biology

Pairing occurs during the breeding season. Captive males solicit females by gently touching their dorsal side. Gives birth to one offspring per year in spring or summer but in captivity birthing occurs year round.

conservation status

Lower Risk/Near Threatened. Another species, Tolypeutes tricinctus, thought to be extinct in wild, was rediscovered in Brazil.

significance to humans

Used for food.

Greater naked-tailed armadillo

Cabassous tatouay

subfamily

Tolypeutinae

taxonomy

Loricatus tatouay (Desmarest, 1804), Paraguay.

other common names

French: Grand tatou à queue nue; German: Grosses Nacktschwanz-Gürteltier; Spanish: Tatú-ai mayor.

physical characteristics

Length 25 in (63.7 cm); weight 11.8 lb (5.35 kg). Dentition: 9/8. They resemble small versions of giant armadillos except no armor on their tails.

distribution

Brazil, Uruguay, Paraguay, and Argentina.

habitat

Found along rivers but also reported in grassland communities.

behavior

Nocturnal forager but may continue to feed near its burrow shortly after sunrise. When harassed they quickly bury themselves within minutes. When handled they vocalize like a grunting pig.

feeding ecology and diet

Primarily myrmecophagous but also feeds on incidental invertebrates present in the mounds. Holes are dug directly into the mounds or where insects are foraging.

reproductive biology

Females give birth to one offspring per year. No information available on seasonality or mating behavior.

conservation status

Not threatened.

significance to humans

None known.

Giant armadillo

Priodontes maximus

subfamily

Tolypeutinae

taxonomy

Dasypus maximus (Kerr, 1792), French Guiana.

other common names

French: Tatou géant; German: Riesengürteltier; Spanish: Tatú carrera.

physical characteristics

Length 4.9 ft (1.5 m); weight 66 lb (30 kg). Dentition 18/19. Largest of the living armadillos. Colored darkly with many narrow bands and an armored tail.

distribution

Venezuela, Colombia, Brazil, and Argentina.

habitat

Tropical forest and open savanna.

behavior

Fossorial and nocturnal. Digs its burrows in open fields and termite mounds, destroying the mound in the process.

feeding ecology and diet

Myrmecophagous (feeds on ants).

reproductive biology

Females give birth to one to two young per litter per year. Polygynous.

conservation status

Listed as Endangered because of overexploitation and loss of habitat.

significance to humans

Hunted for food within its range.

Pink fairy armadillo

Chlamyphorus truncatus

subfamily

Chlamyphorinae

taxonomy

Chlamyphorus truncatus Harlan, 1825, Argentina.

other common names

English: Lesser pink fairy armadillo; French: Petit pichiciego; German: Kleiner Gürteltier; Spanish: Pichiciego menor.

physical characteristics

Length 5.9 in (15 cm); weight 4.2 oz (120 g). Has reduced eyes and ears. Carapace is attached along backbone. Long silky hair found ventrally, extending up under the carapace. Face and rear shields are flexible.

distribution

Argentina.

habitat

Sandy to mixed soil types with limited thorny, scrubby vegetation.

behavior

Fossorial and nocturnal. Captive animals are active periodically throughout the day. They burrow under obstacles rather than going around.

feeding ecology and diet

Omnivorous diet of insects, other invertebrates, plant material, and occasionally carrion.

reproductive biology

Gives birth to one young per litter per year. Probably polygynous.

conservation status

Listed as Endangered.

significance to humans

None known.

Resources

Books

Eisenberg, John F. Mammals of the Neotropics. Vol. 1, The Northern Neotropics: Panama, Colombia, Venezuela, Guyana, Suriname, French Guiana. Chicago: The University of Chicago Press, 1989.

——. The Mammalian Radiations: An Analysis of Trends in Evolution, Adapation, and Behavior. Chicago: The University of Chicago Press, 1981.

Eisenberg, John F., and Kent H. Redford. Mammals of the Neotropics. Vol. 3, The Central Neotropics: Ecuador, Peru, Bolivia, Brazil. Chicago: The University of Chicago Press, 1999.

Emmons, Louise H. Neotropical Rainforest Mammals: A Field Guide. Chicago: The University of Chicago Press, 1990.

Montgomery, G. Gene, ed. The Evolution and Ecology of Armadillos, Sloths, and Vermilinguas. Washington: Smithsonian Institution Press, 1985.

Redford, Kent H., and John F. Eisenberg. Mammals of the Neotropics. Vol. 2, The Southern Cone: Chile Argentina, Uruguay, Paraguay. Chicago: The University of Chicago Press, 1992.

Periodicals

Carter, T. S., and C. D. Encarnaçao. "Characteristics and Use of Burrows by Four Species of Armadillos in Brazil." Journal of Mammalogy 64 (1983): 103–108.

Delsuc, Frederic, et al. "The Evolution of Armadillos, Anteaters, and Sloths Depicted by Nuclear and Mitochondrial Phylogenies: Implications for the Status of the Enigmatic Fossil Eurotamandua." Proceedings of the Royal Society of London, Series B 268 (2001): 1605–1615.

Greegor, D. H. "Preliminary Study of Movements and Home Range of the Armadillo, Chaetophractus vellerosus." Journal of Mammalogy 61 (1980): 334–335.

McDonough, Colleen M. "Social Organization of Nine-banded Armadillos (Dasypus novemcinctus) in a Riparian Habitat." American Midland Naturalist 144 (2000): 139–151.

Merritt, Dennis A., Jr. "The La Plata Three-banded Armadillo in Captivity." International Zoo Yearbook 16 (1976): 153–156.

Pacheco, J., and C. J. Naranjo. "Field Ecology of Dasypus sabanicola in the Flood Savanna of Venezuela." In The Armadillo as an Experimental Model in Biomedical Research. Washington: Pan American Health Organization No. 366 (1978): 13–15.

Shaller, G. B. "Mammals and Their Biomass on a Brazilian Ranch." Arquivos de Zoologia, S. Paulo 31, no. 1 (1983): 1–36.

Colleen M. McDonough, PhD

W. J. Loughry, PhD