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Lifespan, longevity, and ageing

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Maximum longevity: 22.3 years (captivity) Observations: These animals have been estimated to live more than 22 years (Ronald Nowak 1999), and one 22.3 years old record, which seems plausible, has been reported (Ernest 2003). Still, their record longevity in captivity is reported to be only 14.8 years (Richard Weigl 2005). Further studies are necessary.
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Behavior

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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 ; acoustic ; chemical

Other Communication Modes: pheromones

Perception Channels: visual ; tactile ; acoustic ; chemical

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McDonald, K. and J. Larson 2009. "Dasypus novemcinctus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html
author
Kahli McDonald, University of Michigan-Ann Arbor
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Julie Larson, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Conservation Status

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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.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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McDonald, K. and J. Larson 2009. "Dasypus novemcinctus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html
author
Kahli McDonald, University of Michigan-Ann Arbor
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Julie Larson, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Benefits

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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

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McDonald, K. and J. Larson 2009. "Dasypus novemcinctus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html
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Kahli McDonald, University of Michigan-Ann Arbor
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Julie Larson, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Benefits

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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 ; body parts are source of valuable material; research and education; controls pest population

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McDonald, K. and J. Larson 2009. "Dasypus novemcinctus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html
author
Kahli McDonald, University of Michigan-Ann Arbor
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Julie Larson, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Associations

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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

Mutualist Species:

  • Louisiana pine snakes (Pituophis ruthveni)
  • fan-tailed warblers (Euthlypis lachrymosa)

Commensal/Parasitic Species:

  • ticks (Amblyomma auricularium)
  • fungus (Paracoccidiodies brasiliensis)
  • Fungi
  • ticks (Ixodides)
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McDonald, K. and J. Larson 2009. "Dasypus novemcinctus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html
author
Kahli McDonald, University of Michigan-Ann Arbor
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Julie Larson, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Trophic Strategy

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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.

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

Plant Foods: seeds, grains, and nuts; fruit

Other Foods: fungus

Primary Diet: carnivore (Eats terrestrial vertebrates, Insectivore , Eats non-insect arthropods, Vermivore, Scavenger ); omnivore ; mycophage

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McDonald, K. and J. Larson 2009. "Dasypus novemcinctus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html
author
Kahli McDonald, University of Michigan-Ann Arbor
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Julie Larson, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Distribution

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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 (Introduced , Native ); neotropical (Native )

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McDonald, K. and J. Larson 2009. "Dasypus novemcinctus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html
author
Kahli McDonald, University of Michigan-Ann Arbor
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Julie Larson, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Habitat

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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 ; tropical ; terrestrial

Terrestrial Biomes: savanna or grassland ; forest ; rainforest ; scrub forest

Other Habitat Features: suburban ; agricultural ; riparian

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McDonald, K. and J. Larson 2009. "Dasypus novemcinctus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html
author
Kahli McDonald, University of Michigan-Ann Arbor
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Julie Larson, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Life Expectancy

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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.

Range lifespan
Status: captivity:
23+ (high) years.

Typical lifespan
Status: wild:
7 to 20+ years.

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McDonald, K. and J. Larson 2009. "Dasypus novemcinctus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html
author
Kahli McDonald, University of Michigan-Ann Arbor
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Julie Larson, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Morphology

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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).

Range mass: 3.6 to 7.7 kg.

Average mass: 5.5 kg.

Range length: .615 to .800 m.

Average length: .752 m.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

Average basal metabolic rate: 4.655 W.

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McDonald, K. and J. Larson 2009. "Dasypus novemcinctus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html
author
Kahli McDonald, University of Michigan-Ann Arbor
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Julie Larson, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Associations

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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.

Known Predators:

  • pumas (Puma concolor)
  • maned wolves (Chrysocyon brachyurus)
  • coyotes (Canis latrans)
  • red wolves (Canis rufus)
  • American black bears (Ursus americanus)
  • jaguars (Panthera onca)
  • American alligators (Alligator mississippiensis)
  • humans (Homo sapiens)
  • bobcats (Lynx rufus)
  • raptors (Accipitridae)
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McDonald, K. and J. Larson 2009. "Dasypus novemcinctus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html
author
Kahli McDonald, University of Michigan-Ann Arbor
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Julie Larson, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Tanya Dewey, Animal Diversity Web
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Reproduction

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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

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.

Breeding interval: Nine-banded armadillos breed once yearly.

Breeding season: Breeding occurs in early summer (June to July for northern hemisphere, November to December for southern hemisphere).

Range number of offspring: 4 (high) .

Average number of offspring: 4.

Average gestation period: 4 months.

Average weaning age: 2-3 months.

Average age at sexual or reproductive maturity (female): 1 to 2 years.

Average age at sexual or reproductive maturity (male): 1 to 2 years.

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

Average birth mass: 66 g.

Average gestation period: 133 days.

Average number of offspring: 4.

Average age at sexual or reproductive maturity (male)
Sex: male:
365 days.

Average age at sexual or reproductive maturity (female)
Sex: female:
365 days.

Young are typically born in spring but will 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 ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

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McDonald, K. and J. Larson 2009. "Dasypus novemcinctus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html
author
Kahli McDonald, University of Michigan-Ann Arbor
author
Julie Larson, University of Michigan-Ann Arbor
author
Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
editor
Tanya Dewey, Animal Diversity Web
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Nine-banded armadillo

provided by wikipedia EN

 src=
Skeleton of 9-banded on display at the Museum of Osteology.

The nine-banded armadillo (Dasypus novemcinctus), or the nine-banded, long-nosed armadillo, is a medium-sized mammal found in North, Central, and South America, making it the most widespread of the armadillos.[2] Its ancestors originated in South America, and remained there until the formation of the Isthmus of Panama allowed them to enter North America as part of the Great American Interchange. The nine-banded armadillo is a solitary, mainly nocturnal[3][4] animal, found in many kinds of habitats, from mature and secondary rainforests to grassland and dry scrub. It is an insectivore, feeding chiefly on ants, termites, and other small invertebrates. The armadillo can jump 3–4 ft (91–122 cm) straight in the air if sufficiently frightened, making it a particular danger on roads.[5] It is the state small mammal of Texas.

Habitat

The nine-banded armadillo evolved in a warm, rainy environment, and is still most commonly found in regions resembling its ancestral home. As a very adaptable animal, though, it can also be found in scrublands, open prairies, and tropical rainforests. It cannot thrive in particularly cold or dry environments, as its large surface area, which is not well insulated by fat, makes it especially susceptible to heat and water loss.[6]

Range

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The current (circa 2009–2010) range (shaded red), and predicted future range (shaded pink) of the nine-banded armadillo in the USA

The nine-banded armadillo has been rapidly expanding its range both north and east within the United States, where it is the only regularly occurring species of armadillo. The armadillo crossed the Rio Grande from Mexico in the late 19th century, and was introduced in Florida at about the same time by humans. By 1995, the species had become well established in Texas, Oklahoma, Louisiana, Arkansas, Mississippi, Alabama, Georgia and Florida, and had been sighted as far afield as Kansas, Missouri, Tennessee, Kentucky, and South Carolina. A decade later, the armadillo had become established in all of those areas and continued its migration, being sighted as far north as southern Nebraska, southern Illinois, and southern Indiana.[7] The primary cause of this rapid expansion is explained simply by the species having few natural predators within the United States, little desire on the part of Americans to hunt or eat the armadillo, and the animals' high reproductive rate. The northern expansion of the armadillo is expected to continue until the species reaches as far north as Ohio, Pennsylvania, New Jersey and Connecticut, and all points southward on the East Coast of the United States. Further northward and westward expansion will probably be limited by the armadillo's poor tolerance of harsh winters, due to its lack of insulating fat and its inability to hibernate.[7] As of 2009, newspaper reports indicated the nine-banded armadillo seems to have expanded its range northward as far as Omaha, Nebraska in the west, and Kentucky Dam and Evansville, Indiana, in the east.[8][9][10] In 1995, armadillos were only seen in the southern tip of South Carolina, and within two to three years, they had swept across most of the state.[6] In late 2009, North Carolina began considering the establishment of a hunting season for armadillo, following reports that the species has been moving into the southern reaches of the state (roughly between the areas of Charlotte and Wilmington).[11][12] Outside the United States, the nine-banded armadillo ranges southward through Central and South America into northern Argentina and Uruguay, where it is still expanding its range.[6]

Diet

Nine-banded armadillos are generally insectivores. They forage for meals by thrusting their snouts into loose soil and leaf litter and frantically digging in erratic patterns, stopping occasionally to dig up grubs, beetles (perhaps the main portion of this species' prey selection), ants, termites, and worms, which their sensitive noses can detect through 8 in (20 cm) of soil. They then lap up the insects with their sticky tongues. Nine-banded armadillos have been observed to roll about on ant hills to dislodge and consume the resident ants. They supplement their diets with amphibians and small reptiles, especially in more wintery months when such prey tends to be more sluggish, and occasionally bird eggs and baby mammals. Carrion is also eaten, although perhaps the species is most attracted to the maggots borne by carcasses rather than the meat itself. Less than 10% of the diet of this species is composed by nonanimal matter, though fungi, tubers, fruits, and seeds are occasionally eaten.[13][14]

Anatomy

Nine-banded armadillo in natural habitat (near Memphis, TN, 2010)
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Taxidermized armadillo shell

Nine-banded armadillos generally weigh from 2.5–6.5 kg (5.5–14.3 lb), though the largest specimens can scale up to 10 kg (22 lb). They are one of the largest species of armadillos.[15] Head and body length is 38–58 cm (15–23 in), which combines with the 26–53 cm (10–21 in) tail, for a total length of 64–107 cm (25–42 in). They stand 15–25 cm (5.9–9.8 in) tall at the top of the shell.[15][16] The outer shell is composed of ossified dermal scutes covered by nonoverlapping, keratinized epidermal scales, which are connected by flexible bands of skin. This armor covers the back, sides, head, tail, and outside surfaces of the legs. The underside of the body and the inner surfaces of the legs have no armored protection. Instead, they are covered by tough skin and a layer of coarse hair. The vertebrae attach to the carapace.[17] The claws on the middle toes of the forefeet are elongated for digging, though not to the same degree as those of the much larger giant armadillo of South America.[6] Their low metabolic rate and poor thermoregulation make them best suited for semitropical environments.[17] Unlike the South American three-banded armadillos, the nine-banded armadillo cannot roll itself into a ball. It is, however, capable of floating across rivers by inflating its intestines, or by sinking and running across riverbeds. The second is possible due to its ability to hold its breath for up to six minutes, an adaptation originally developed for allowing the animal to keep its snout submerged in soil for extended periods while foraging.[17] Although nine is the typical number of bands on the nine-banded armadillo, the actual number varies by geographic range.[17] Armadillos possess the teeth typical of all sloths and anteaters. The teeth are all small, peg-like molars with open roots and no enamel. Incisors do form in the embryos, but quickly degenerate and are usually absent by birth.[17]

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Nine-banded armadillo on its hind legs

Behavior

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Armadillo burrow
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in Nuevo León, Mexico

Nine-banded armadillos are solitary, largely nocturnal animals that come out to forage around dusk. They are extensive burrowers, with a single animal sometimes maintaining up to 12 burrows on its range. These burrows are roughly 8 in (20 cm) wide, 7 ft (2.1 m) deep, and 25 ft (7.6 m) long. Armadillos mark their territory with urine, feces, and excretions from scent glands found on the eyelids, nose, and feet. Males hold breeding territories and may become aggressive in order to keep other males out of their home range to increase chances of pairing with a female.[18] Territorial disputes are settled by kicking and chasing. When they are not foraging, armadillos shuffle along fairly slowly, stopping occasionally to sniff the air for signs of danger.

Predation

If alarmed, nine-banded armadillos can flee with surprising speed. Occasionally, a large predator may be able to ambush the armadillo before it can clear a distance, and breach the hard carapace with a well-placed bite or swipe. If the fleeing escape fails, the armadillo may quickly dig a shallow trench and lodge itself inside. Predators are rarely able to dislodge the animal once it has burrowed itself, and abandon their prey when they cannot breach the armadillo’s armor or grasp its tapered tail.[6] Due to their softer carapaces, juvenile armadillos are more likely to fall victim to natural predation and their cautious behavior generally reflects this. Young nine-banded armadillos tend to forage earlier in the day and are more wary of the approach of an unknown animal (including humans) than are adults. Their known natural predators include cougars (perhaps the leading predator), maned wolves, coyotes, black bears, red wolves, jaguars, alligators, bobcats, and large raptors. By far the leading predator of nine-banded armadillos today is humans, as armadillos are locally harvested for their meat and shells and many thousands fall victim to auto accidents every year.[19][20]

Reproduction

Mating takes place during a two-to-three month long mating season, which occurs from July–August in the Northern Hemisphere and November–January in the Southern Hemisphere. A single egg is fertilized, but implantation is delayed for three to four months to ensure the young will not be born during an unfavorable time. Once the zygote does implant in the uterus, a gestation period of four months occurs, during which the zygote splits into four identical embryos, attached by a common placenta.[21] They are born in March and weigh 3 oz (85 g).[22] After birth, the quadruplets remain in the burrow, living off the mother’s milk for about three months. They then begin to forage with the mother, eventually leaving after six months to a year.[6][17]

Nine-banded armadillos reach sexual maturity at the age of one year, and reproduce every year for the rest of their 12–to-15 year lifespans. A single female can produce up to 56 young over the course of her life. This high reproductive rate is a major cause of the species’ rapid expansion.[6]

Effect on the environment

The foraging of nine-banded armadillo can cause mild damage to the root systems of certain plants. Skunks, cotton rats, burrowing owls, pine snakes, and rattlesnakes can be found living in abandoned armadillo burrows.[6] Occasionally, the armadillo may threaten the endangered gopher tortoise by aggressively displacing them from their burrows and claiming the burrows for themselves.[13] Studies have shown the fan-tailed warbler habitually follows armadillos to feed on insects and other invertebrates displaced by them.[23]

They are typically hunted for their meat, which is said to taste like pork, but are more frequently killed as a result of their tendency to steal the eggs of poultry and game birds. This has caused certain populations of the nine-banded armadillo to become threatened, although the species as a whole is under no immediate threat.[6] They are also valuable for use in medical research, as they are among the few mammals other than humans susceptible to leprosy.[17] In Texas, nine-banded armadillos are raised to participate in armadillo racing, a small-scale, but well-established sport in which the animals scurry down a 40-foot track.[6]

Hoover hog

During the Great Depression, the species was hunted for its meat in East Texas, where it was known as poor man’s pork,[24] or the "Hoover hog" by those who considered President Herbert Hoover to be responsible for the Depression.[25] Earlier, German settlers in Texas would often refer to the armadillo as Panzerschwein ("armored pig"). In 1995, the nine-banded armadillo was, with some resistance, made the state small mammal of Texas,[26] where it is considered a pest and is often seen dead on the roadside. They first forayed into Texas across the Rio Grande from Mexico in the 19th century, eventually spreading across the southeast United States.[25]

Subspecies

  • D. n. aequatorialis Lönnberg, 1913
  • D. n. fenestratus Peters, 1864
  • D. n. hoplites Allen, 1911
  • D. n. mexianae Hagmann, 1908
  • D. n. mexicanus Peters, 1864
  • D. n. novemcinctus Linnaeus, 1758

North American subspecies exhibit reduced genetic variability compared with the subspecies of South America, indicating the armadillos of North America are descended from a relatively small number of individuals that migrated from south of the Rio Grande.[17]

References

  1. ^ Loughry, J.; McDonough, C. & Abba, A.M. (2014). "Dasypus novemcinctus". IUCN Red List of Threatened Species. IUCN. 2014: e.T6290A47440785. doi:10.2305/IUCN.UK.2014-1.RLTS.T6290A47440785.en.
  2. ^ Gardner, A.L. (2005). "Order Cingulata". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 94–95. ISBN 978-0-8018-8221-0. OCLC 62265494.
  3. ^ Armadillo Observation. Msu.edu. Retrieved on October 17, 2013.
  4. ^ Mammals of Kansas – Kansas University. Ksr.ku.edu. Retrieved on October 17, 2013.
  5. ^ "How high can a nine-banded armadillo jump?". Everyday Mysteries. Library of Congress.
  6. ^ a b c d e f g h i j Wildlife Explorer: Nine-Banded Armadillo. USA: International Masters Publishers, 1998.
  7. ^ a b "Armadillo Expansion". Armadillo Online. Archived from the original on July 6, 2013. Retrieved June 7, 2010. Cite journal requires |journal= (help)
  8. ^ Schroeder, Owen (October 4, 2008) Armadillos take up residence in Tenn. theleafchronicle.com
  9. ^ "Armadillo sightings becoming common". Evansville Courier and Press. June 29, 2008. Retrieved June 7, 2010.
  10. ^ Venable, Sam (2009). "Keeping all fingers intact". Knoxville News Sentinel. Retrieved June 8, 2010.
  11. ^ Windham, Steve. "Public Hearings Applying to 2010–2011 Fishing, Hunting and Trapping Seasons" (PDF). North Carolina Wildlife Resources Commission. Archived from the original (PDF) on November 20, 2009. Retrieved June 7, 2010. Cite journal requires |journal= (help)
  12. ^ Weaver, Jefferson (December 9, 2009). "New regulations feature armored possums". The News Reporter. Retrieved June 8, 2010.
  13. ^ a b Chapman, J. and Feldhamer, G. (1982) Wild Mammals of North America: Biology, Management, and Economics, Johns Hopkins University Press, ISBN 0801823536.
  14. ^ Schmidly, D. and William, D. (2004) "Nine-banded Armadillo" in The Mammals of Texas. Austin: University of Texas Press, ISBN 0292702418.
  15. ^ a b 3.8 Armadillos. Fao.org. Retrieved on October 17, 2013.
  16. ^ Burnie D and Wilson DE (Eds.) (2005) Animal: The Definitive Visual Guide to the World's Wildlife. DK Adult, ISBN 0789477645
  17. ^ a b c d e f g h Feldhamer, George A.; Lee C. Drickhamer; Stephen H. Vessey; Joseph F. Merritt; Carey Krajewski (2007). Mammalogy: Adaptation, Diversity, Ecology. Baltimore, Maryland: Johns Hopkins University Press. ISBN 978-0-8018-8695-9.
  18. ^ McDonough, Colleen M. (January 1, 1997). "Pairing Behavior of the Nine-banded Armadillo (Dasypus novemcinctus)". The American Midland Naturalist. 138 (2): 290–298. doi:10.2307/2426822. JSTOR 2426822.
  19. ^ Moeller, W. (1990) "Modern Xenarthrans", pp. 583–626 in S Parker (ed.) Grzimek’s Encyclopedia of Mammals, Vol. 2, English Language Edition. New York: McGraw-Hill, Inc., ISBN 0079095089
  20. ^ Weckel, M.; Giuliano, W.; Silver, S. (2006). "Cockscomb Revisited: Jaguar Diet in the Cockscomb Basin Wildlife Sanctuary, Belize1". Biotropica. 38 (5): 687. doi:10.1111/j.1744-7429.2006.00190.x.
  21. ^ The Mammals of Texas, Davis and Schmidly 1994
  22. ^ Field guide to mammals. 1996. ISBN 0-679-44631-1
  23. ^ Schaefer, R. R.; Fagan, J. F. (2006). Husak, Michael (ed.). "Commensal Foraging by a Fan-Tailed Warbler (Euthlypis Lachrymosa) with a Nine-Banded Armadillo (Dasypus Novemcinctus) in Southwestern Mexico". The Southwestern Naturalist. 51 (4): 560. doi:10.1894/0038-4909(2006)51[560:CFBAFW]2.0.CO;2.
  24. ^ TEXAS PARKS & WILDLIFE, Armadillos. Tpwd.state.tx.us (October 25, 2006). Retrieved on October 17, 2013.
  25. ^ a b Armadillo from the Handbook of Texas Online
  26. ^ Texas State Symbols - Texas State Library and Archives Commission. Accessed January 17, 2014.
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Nine-banded armadillo: Brief Summary

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 src= Skeleton of 9-banded on display at the Museum of Osteology.

The nine-banded armadillo (Dasypus novemcinctus), or the nine-banded, long-nosed armadillo, is a medium-sized mammal found in North, Central, and South America, making it the most widespread of the armadillos. Its ancestors originated in South America, and remained there until the formation of the Isthmus of Panama allowed them to enter North America as part of the Great American Interchange. The nine-banded armadillo is a solitary, mainly nocturnal animal, found in many kinds of habitats, from mature and secondary rainforests to grassland and dry scrub. It is an insectivore, feeding chiefly on ants, termites, and other small invertebrates. The armadillo can jump 3–4 ft (91–122 cm) straight in the air if sufficiently frightened, making it a particular danger on roads. It is the state small mammal of Texas.

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