Nine-banded Armadillo

About the nine-banded armadillo

The nine-banded armadillo, also called the nine-banded long-nosed armadillo or common armadillo, is a species of armadillo native to South America. The Mexican long-nosed armadillo of North America was formerly classified as a subspecies of the nine-banded armadillo but is now recognized separately. Five subspecies of the nine-banded armadillo are described across its range.

It is one of the largest armadillo species, generally weighing 5.5 to 14.3 lb (2.5–6.5 kg), though the biggest individuals can reach 22 lb (10 kg). Head and body length runs 15 to 23 in (38–58 cm), and the tail adds another 10 to 21 in (26–53 cm), for a total length of 25 to 42 in (64–107 cm). At the shoulder, they stand 5.9 to 9.8 in (15–25 cm) tall. The animal's defining feature is its shell: ossified plates of bone (scutes) covered by hard, keratinized skin, connected by flexible bands that let the armadillo move. This armor covers the back, sides, head, tail, and the outer surfaces of the legs, while the belly and the insides of the legs are protected only by tough skin and coarse hair. The middle claws on the front feet are elongated for digging, a smaller version of the digging claws seen on the much larger giant armadillo of South America.

Unlike the three-banded armadillos of South America, the nine-banded armadillo cannot roll itself into a ball for defense. It can, however, cross rivers either by inflating its intestines and floating or by sinking and walking across the riverbed, holding its breath for as long as six minutes — an ability that also lets it keep its snout buried in soil while foraging. Despite the name, the actual number of bands on the shell varies by geographic population, with nine being typical rather than universal. Its teeth are small, peg-like molars with open roots and no enamel, the same basic tooth pattern found in sloths and anteaters; incisors form in the embryo but are usually gone by birth.

Behavior and diet

Nine-banded armadillos are solitary and largely nocturnal, emerging to forage around dusk. They are prolific diggers, and a single animal may maintain up to 12 burrows across its home range, each roughly 8 in (20 cm) wide, 7 ft (210 cm) deep, and 25 ft (760 cm) long. They mark territory with urine, feces, and scent-gland secretions found on the eyelids, nose, and feet. Males defend breeding territories and can become aggressive toward rival males, settling disputes by kicking and chasing rather than serious fighting. Outside of foraging, they move at a fairly slow shuffle, pausing often to sniff the air for danger, though they can flee with surprising speed if alarmed.

The species is an insectivore. It forages by thrusting its snout into loose soil and leaf litter and digging in erratic bursts, using a highly sensitive nose that can detect prey through 8 in (20 cm) of soil. Beetles make up a large share of the diet, along with grubs, ants, termites, grasshoppers, millipedes, centipedes, arachnids, and worms, all gathered with a sticky tongue. Armadillos have even been seen rolling on ant hills to dislodge and eat the resident ants. In colder months, when such prey tends to be more sluggish, they add amphibians, small reptiles, bird eggs, and baby mammals to the menu, along with carrion — though they appear to be drawn more to the maggots on a carcass than the meat itself. Plant matter such as fungi, tubers, fruits, and seeds makes up less than 10 percent of the diet.

Mating occurs over a two- to three-month season from November to January. A single fertilized egg develops into a blastocyst, but implantation is delayed three to four months so the young are not born at an unfavorable time of year. Once implanted, the blastocyst splits into four genetically identical embryos, each with its own amnion and umbilical cord but sharing one placenta. After a four-month gestation, the quadruplets are born weighing about 3 oz (85 g) each. They nurse in the burrow for around three months, then begin foraging alongside their mother before leaving the family group between six months and a year of age. Armadillos reach sexual maturity at one year and can go on reproducing annually for the rest of a 12- to 15-year lifespan; a single female may produce up to 56 young over her lifetime, a reproductive rate that has fueled the species' rapid range expansion.

Range and habitat

The nine-banded armadillo's ancestral range is South America, where it evolved in warm, rainy conditions, and it ranges through most of the continent except the Guiana Shield, home to the separately described Guianan long-nosed armadillo. It remains most common in habitats resembling this original range but has proven highly adaptable, also turning up in scrubland, open prairie, and tropical rainforest. Its large surface area is poorly insulated by fat, which makes the species vulnerable to heat and water loss and limits how far it can push into particularly cold or dry environments.

Conservation status

The nine-banded armadillo is listed as Least Concern (LC) by the IUCN. The species as a whole faces no immediate threat, though certain local populations have declined. People hunt the animal for its meat, said to taste like pork, but more often kill it for raiding the eggs of poultry and game birds. Armadillos are also valuable to medical research, since they are among the few mammals besides humans known to be susceptible to leprosy. Their burrowing has a broader ecological effect, too: abandoned armadillo burrows go on to house skunks, cotton rats, burrowing owls, and rattlesnakes.