Dasypus novemcinctus

Geographic Range

Nine-banded armadillos are found in South, Central, and North America, and have the largest range of any extant species of armadillo , from Argentina and Uruguay, through Central America and into the southern United States. As early as 1850, nine-banded armadillos were found no further north than Texas. Beginning in the late 19th century, they gradually expanded their range to the northeast. They have been spotted as far east as Florida and are common as far north as Missouri. In 2000, the dead body of a nine-banded armadillo was discovered in central Illinois. Migration and establishment of populations northward is likely limited by the severity of cold, winter weather, for which the species does not have a strong tolerance. However, if winter seasons become milder, nine-banded armadillos may continue their migration northward. They can survive short periods of severe cold by remaining in a burrow for days at a time. Another factor that has limited their migration westward is dependence on rainfall or other sources of water. For this reason, nine-banded armadillos have not migrated into the arid, desert regions of New Mexico and other western states.

Increasing human populations and development of transportation routes are thought to help rather than hinder the geographic expansion of nine-banded armadillos. The construction of roads and bridges have both facilitated human introduction of nine-banded armadillos into new areas, as well as provided a means for wild nine-banded armadillos to move across the wide waterways and other natural obstacles that would had previously prevented their expansion. Nine-banded armadillos are able swimmers due to their ability to hold air in their digestive tract, increasing buoyancy; they are also able to walk along river bottoms as a result of their ability to maintain a large oxygen debt. Even so, they do not readily cross large bodies of water. Further, human activities have caused a decline in many natural predators of North American nine-banded armadillos.

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
  • native native
• neotropical neotropical
  • native native

Habitat

Nine-banded armadillos most often inhabit forest and scrub-brush areas in tropical and temperate regions. They are also found in grasslands and savanna regions around woody areas, but much prefer forests over grasslands because they forage in forest litter for small invertebrates. Nine-banded armadillos are not often found in arid regions; they thrive especially in riparian habitats or areas with a sufficient amount of water and/or at least 38 cm of rain annually. This association with water could be due the increased number of available food sources in wetter areas or to the softer soil conditions, making digging and burrowing easier. As long as sufficient food and water supplies are available, nine-banded armadillos are very adaptable to different habitats. They have been observed near swampy or marshy regions as well, but do not commonly inhabit them.

Temperature is also an important factor in choice of habitat. Nine-banded armadillos begin to shiver at temperatures below 22°C, but the warmth of the burrow allows an armadillo to inhabit temperate areas during milder winters. At present, nine-banded armadillos are not common in any regions in which more than 24 freeze-over days occur annually or the average January temperature drops below -2°C. Nine-banded armadillos are also more populous in low-lying lands, often around sea-level.

The habitat of nine-banded armadillos is not limited by human presence. They do not often inhabit areas of dense human population, but the northeastern expansion of nine-banded armadillos in the United States seems to be linked to man-made roads, bridges, railroads and other travel routes. This suggests that armadillos use human developments to their advantage. Their coexistence with humans is often evident by the presence of nine-banded armadillo roadkill along these routes.

Within the forests, grasslands, and shrublands that nine-banded armadillos inhabit, they make their homes in underground burrows. Burrows vary in size, but can be up to 5 m long and 2 m deep. Nine-banded armadillos may bring some grasses and leaves inside their burrow and they often try to hide the entrance by placing plant debris around it. A nine-banded armadillo may have up to 12 den sites, but the average is 4 or 5. A male and female may share these burrows during mating season, but usually a burrow is only shared by a female and her young or by young siblings.

• Habitat Regions
• temperate temperate
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest
• rainforest rainforest
• scrub forest scrub forest

• Other Habitat Features
• suburban suburban
• agricultural agricultural
• riparian riparian

Physical Description

The outer body of Nine-banded armadillos are unmistakable. Like many other armadillos , Dasypus novemcinctus is covered by an outer body armor made up of bony plates covered in a leathery keratinous skin. These scales (osteoderms) provide a hard but flexible covering. The osteoderms are typically rectangular or pentagonal in shape and are developed later than the rest of the skeleton. The armor comprises about 16% of body weight and is divided into three main areas of coverage on the body: a pelvic shield, a shield on the shoulder region, and the characteristic bands of the back. Typically, nine-banded armadillos have 9 visible bands, but this number may vary from 8 to 11. Each band is separated by a thin epidermal layer and hairs. Scales grow continuously and wear, but are never fully shed. The average body length is .752 m. The tail averages about 0.3 m long and is covered by 12 to 15 rings of scales.

The head is partially covered in these bony/keratinous scales, but the ears lack them. Instead, ears are hairless and covered in a rough, bumpy skin. The underside also lacks any armored protection and is of a paler color, generally appearing slightly yellow. The long snout is much softer and pinkish in color, appearing almost pig-like with it narrow, tapered shape. The face, neck, and underside are covered in small clusters of hair.

Nine-banded armadillos have short legs with 4 toes on the forefoot and 5 toes on the hindfoot; all digits have strong claws, and the middle claws are largest of all. The skull lacks ossified auditory bullae. It is dorso-ventrally flattened and has a very distinct dentition. The dentary is v-shaped and the total tooth number ranges from 28 to 32 (8/8). Teeth are simple, small and cylindrical (peg-like). They lack enamel and continue to grow throughout the animal's lifetime. Nine-banded armadillos possess long, sticky tongues, which they use in foraging for insects .

Sexual dimorphism in nine-banded armadillos is minor with males weighing slightly more than females (the average male weighs 5.5 to 7.7 kg, while the average female weighs 3.6 to 6.0 kg). Nine-banded armadillos maintain a low body temperature, usually ranging from 30° to 35° C. Their basal metabolic rate is also low given their mass (384.4 kJ/day).

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

During the summer breeding season, nine-banded armadillos are often seen pairing. Nine-banded armadillos are typically solitary animals, so a male and female maintaining close proximity to one another is unusual. During pairing, the male remains within a few meters of, and occasionally interacts with, the female as the two forage. Other behaviors accompany the pairing, including dorsal touches, tail wagging, tail lifting by the female (which exposes the genitalia), and sniffing and vigilance by the males, which allows them to maintain their proximity. In some instances, armadillo pairs have been observed sharing a burrow during pairing/breeding season.

It is thought that a male maintains this close proximity to the female in order to claim and protect her from other males. Usually only males who have an exclusive home range pair. In some instances, male on male aggression takes place as a male protects his rights to a female. It is likely that maintaining such close proximity allows the male to determine when the female is receptive. Females constantly appear to retreat from males, which may be an effort to prevent the male from keeping too close before she is ready to mate. The secretions by the anal glands may have a scent that changes as a female becomes ready to ovulate. Some observational studies have shown that within a given breeding season, nine-banded armadillos are polygnous with respect to pairing, however, pairing may not lead to copulation. This is a topic still under study.

• Mating System
• polygynous polygynous

Females have a large external clitoris, while males lack an external scrotum and testes are internal. The female reproductive tract includes a simplex uterus and paired ovaries and oviducts. Most females ovulate once a year, usually in early summer (June to July in the northern hemisphere, November to December in the southern hemisphere). Copulation occurs during this time of year, with the female positioned on her back.

During conception, only a single ovum is fertilized. The blastocyst stays in the uterus for about 14 weeks before implantation. During this time, fluids from the uteran lining keep the blastocyst lubricated and provide nutrients. Nine-banded armadillo reproduction involves monozygotic polyembryony. That is, when a blastocyst finally implants in the wall of the uterus, it buds into 4 identical embryos. Every embryo develops its own amniotic cavity. This embryonic process almost always results in the birth of four identical quadruplets.

The quadruplets are often born in early spring, after about a 4 month gestation period. Delayed implantation allows birthing to happen during the spring, when temperatures are much warmer and food is abundant.

Young are born in an advanced state of development, closely resembling their adult counterparts but smaller in size. The eyes open quickly, but their leathery skin does not harden into its characteristic armor for a few weeks. Young of both sexes may begin breeding as early as the summer following their birth, but they may not reach full sexual maturity until the age of 2 years. Full development and maturity is attained by the age of 3 or 4 years.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous
• delayed implantation delayed implantation

Young are typically born in spring but do not leave their burrows until late spring or early summer, after at least a few weeks. When they emerge, they are ready to begin foraging with their mother. The mother may provide milk for up to 2 to 3 months before weaning. After weaning the young may remain with their mother for a few additional months, but no significant long term care or parent-offspring relationship is known. A young nine-banded armadillo may share a burrow and foraging areas with its siblings during its first summer and early fall.

• Parental Investment
• precocial precocial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Reported life expectancies of nine-banded armadillos range from as low as 7 to 8 years to more than 20 years. At least one nine-banded armadillo in captivity reached 23 years of age. Juveniles have a higher mortality rate than adults.

The factors influencing longevity of nine-banded armadillos include climate, predation, and disease. Because this species does not have a significant amount of hair or body fat, it does not cope well with cold temperatures. A large adult male can survive no longer than 10 days at 0° C without starving. The larger the animal, the more likely it will survive colder temperatures. Other environmental conditions, such as drought, also have an impact on nine-banded armadillo mortality. In one area that experienced a severe drought, the nine-banded armadillo population completely disappeared due to death or migration (McDonough and Loughry, 1997).

Predation and death by humans, both purposeful and accidental, are other causes of mortality. A juvenile is more likely to be killed by a predator in the wild than is an adult due to its weaker physical state and softer armor.

Disease can be an important contributor to nine-banded armadillo mortality; leprosy, in particular, has an important impact. In one population of nine-banded armadillos, 30% of adults were found to have the bacterium associated with the disease, while 17% had the antibodies, indicating previous exposure.

Behavior

Nine-banded armadillos are nocturnal or crepuscular but forage earlier in the day during cold or cloudy periods. They do not hibernate, but in the northern part of their distribution, nine-banded armadillos are more active during summer months. They cross streams or rivers by swimming or simply walking across the bottom. An armadillo can accumulate a large oxygen debt and hold its breath for up to 6 minutes. By swallowing air, the animal can also regulate its buoyancy to some degree. Armadillos tire quickly, however, and cannot cross wide bodies of water.

Nine-banded armadillos dig burrows by loosening soil with their noses and forelimbs and then kick the soil away with their hind limbs. A burrow may have several entrances, but there is a main entrance that the animal preferentially uses. Burrows are between 1 and 5 m in length and located a few cm to 2 m below ground. Nine-banded armadillos may have multiple burrows, including one for nesting and several shallower ones used as food traps. Nine-banded armadillos also use naturally occurring above-ground crevices as nesting sites. The animals carry nesting materials, such as twigs and leaves, by clutching items to themselves with their forelimbs and hopping bipedally. Rotting materials may be removed after heavy rainfall. Aside from mating pairs or a mother with a very young litter, nine-banded armadillos typically do not share burrows. However, incidences of non-related adults sharing a nest have been documented in cold weather, and it is speculated that this may be a way for these armadillos to thermoregulate at the northern limits of their distribution.

Nine-banded armadillos are rarely aggressive toward one another, although a pregnant or nursing mother may be unusually aggressive, even toward her own older offspring. During the mating season, older males occasionally exhibit aggressive behavior toward younger males. Aggressive behavior, such as kicking or chasing, usually does not result in serious injury. When agitated by a perceived threat, nine-banded armadillos usually freeze. They can also jump up straight in the air and sprint over short distances. A frightened nine-banded armadillo usually seeks a burrow, and once inside, arches its back and braces its feet so that it is difficult to remove. If a burrow is not nearby, the animal may seek dense thorny underbrush, as it is relatively protected by its tough exterior.

While nine-banded armadillos curl up, they are not capable of curling itself into a perfect ball like other species, such as three-banded armadillos .

• Key Behaviors
• terricolous
• fossorial fossorial
• diurnal diurnal
• nocturnal nocturnal
• crepuscular crepuscular
• motile motile
• sedentary sedentary
• solitary solitary
• territorial territorial

Home Range

Estimates for the home range size of nine-banded armadillo range from 0.63 to 20.1 hectares. This variation in size is attributable to physical conditions of the surrounding land, such as soil type and water availability. Home range size is also believed to increase with age. Female and male home ranges tend to be of similar size, although adult males tolerate much less overlap. Adults of both sexes may share home ranges with juveniles and members of the opposite sex. A small number of individuals are transient.

Communication and Perception

Olfaction is the primary mode of perception used by nine-banded armadillos. Olfaction is essential while foraging. Nine-banded armadillos travel with their nose just above the ground and can smell invertebrates up to 20 cm below the surface. They can also stand bipedally, bracing themselves with their tail and sniff the air to locate food. Smell may also be important for nine-banded armadillos to orient themselves and recognize familiar places, although there is no evidence that they employ scent trails. The animals’ reliance on scent is reflected by corresponding development in their forebrains.

Nine-banded armadillos also have a good sense of hearing, which the animals use in avoiding predation or other sources of potential danger. Mating pairs also communicate with a “chucking” sound. Nine-banded armadillos have a poor sense of vision, which is useless except at close distances, and they are thought to have a poor sense of touch. Dasypodidae species have fewer taste buds than other mammals , so it is likely that nine-banded armadillos have a poor sense of taste as well.

• Communication Channels
• tactile tactile
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• pheromones pheromones

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Nine-banded armadillos are generalist, opportunistic feeders. Almost 500 separate food items make up their diet, and over ninety percent of their diet (by volume) is made up of animal matter. Adult and larval beetles may be the largest component, but nine-banded armadillos also feed on termites , millipedes , centipedes , ants , grasshoppers , arachnids , earthworms , and several other insects and terrestrial invertebrates. After preying on ant hills, nine-banded armadillos often roll around vigorously, presumably to remove ants from themselves. Nine-banded armadillos also feed on small reptiles and amphibians , especially in the winter when these animals are more sluggish. They occasionally take baby mammals or bird eggs. Less than ten percent of their diet is made up of plant matter, such as fruit, seeds, and fungi. Dirt, twigs, tree bark, and other indigestible materials have been found in their stomachs, but the ingestion of such materials is probably accidental. Nine-banded armadillos occasionally eat carrion, but the animal is probably more interested in the maggots that inhabit corpses than the meat itself. Nine-banded armadillos do not chew small prey, but they do chew large invertebrates, vertebrate animal matter, and plant matter. While foraging, nine-banded armadillos rely primarily on their sense of smell to locate food items, and they often visit shallow burrows in search of trapped invertebrates.

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • insectivore insectivore
  • eats non-insect arthropods
  • vermivore
  • scavenger scavenger
• omnivore omnivore
• mycophage mycophage

• Animal Foods
• mammals
• amphibians
• reptiles
• eggs
• carrion carrion
• insects
• terrestrial non-insect arthropods
• terrestrial worms

• Plant Foods
• seeds, grains, and nuts
• fruit

• Other Foods
• fungus

Predation

Nine-banded armadillos have many natural predators, including pumas , maned wolves , coyotes , black bears , red wolves , jaguars , alligators , bobcats , and raptors , which prey on baby nine-banded armadillos. It is believed that the decline of many natural predator populations in North America has aided in the rapid northern expansion of this species. Because of their softer carapace, juveniles are more susceptible to predation than are adults, and this is reflected in their behavior. Young nine-banded armadillos tend to forage earlier in the day and are more wary of human approach than are adults. Nine-banded armadillos can jump straight in the air and sprint over short distances to avoid predators, and often flee to the cover of dense, thorny underbrush or nearby burrows. The tapered design of their tails makes them difficult to grasp and, once inside a burrow, nine-banded armadillos arch their backs and brace themselves against possible removal. Humans are also predators to nine-banded armadillos, both intentionally and accidentally. Nine-banded armadillos are hunted in many rural areas for their meat and skin, while auto accidents claim the lives of thousands of individuals each year.

Ecosystem Roles

Armadillos are scavengers and consumers of many kinds of invertebrates. They have a relatively lower body temperature than other mammals and their carapace makes them poor thermoregulators. These characteristics result in a poor immune system. Thus, nine-banded armadillos are host to a variety of bacterial and protozoan parasites, perhaps the most notable being Mycobacterium leprae , the bacterium responsible for leprosy. Nine-banded armadillos are also associated with some parasitic ticks, such as Amblyomma auricularium . Because they inhabit damp, dirt-filled environments, nine-banded armadillos harbor several species of fungi, some of which are responsible for human diseases. It is unclear whether these fungi function as commensalists or parasites. For example, nine-banded armadillos infected with the fungus, Paracoccidiodies brasiliensis , which causes a mycosis in humans, appear healthy. Yet the fungus was detected in the animals’ lymph nodes, indicating illness.

Fan-tailed warblers have been observed following nine-banded armadillos while they forage, searching for prey revealed by the armadillos’ activities. The abandoned burrows of nine-banded armadillos may be occupied by pine snakes . However, these burrows may also pose a threat to large terrestrial vertebrates that accidentally step in them. It has been proposed that nine-banded armadillo carrion resulting from road kill is becoming an important food source for some species of birds . Nine-banded armadillos were introduced to Florida, and there is concern that they may be exerting predation pressure on endangered endemic Florida reptiles . In addition, nine-banded armadillos may force Gopherus polyphemus , an endangered Floridian tortoise, from their burrows and claim them for itself.

• Ecosystem Impact
• creates habitat

Economic Importance for Humans: Positive

Armadillos , including nine-banded armadillos, play a large role in medical research because they harbor a number of protozoan, bacterial, and fungal pathogens that are responsible for human disease. Perhaps the two most heavily studied pathogens are the fungus Paracoccidiodies brasiliensis , which is responsible for a widespread mycosis in Brazil, and the bacterium Mycobacterium leprae , which causes leprosy. Nine-banded armadillos are important predators of a variety of commong insect agricultural pests. In addition, nine-banded armadillos are hunted for their meat and skin, which is used to make various trinkets.

• Positive Impacts
• food food
• body parts are source of valuable material
• research and education
• controls pest population

Economic Importance for Humans: Negative

Despite feeding on crop pests, nine-banded armadillos can be a nuisance for human agriculture. They feed on several crops, including peanuts, corn and cantaloupe. Their burrows pose threats to livestock animals, who may accidentally step in them. Furthermore, their burrows can weaken road shoulders and dikes. They also carry and can transmit diseases.

• Negative Impacts
• injures humans
  • carries human disease
• crop pest

Conservation Status

Due to their high reproduction rate and expanding distribution, nine-banded armadillos are not considered in any danger. In fact, throughout most of their distribution, their population size is increasing.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

George Hammond (editor), Animal Diversity Web Staff, Gail McCormick (editor), Animal Diversity Web Staff.

Kahli McDonald (author), University of Michigan-Ann Arbor, Julie Larson (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), University of Michigan-Ann Arbor, Tanya Dewey (editor), University of Michigan-Ann Arbor.

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