Like many other armadillos, nine-banded armadillos are 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 scales 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 layer of skin and hairs. Scales grow continuously and wear, but are never fully shed. The average body length is 0.752 m. The tail averages about 0.3 m in length and is covered by 12 to 15 rings of scales. (Chapman and Feldhamer, 1982; Macdonald, 1984; Stangle, 1994; Wilson and Ruff, 1999)
The head of a nine-banded armadillo is covered in these bony/keratinous scales, but their ears are not. 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. (Chapman and Feldhamer, 1982; Stangle, 1994)
Nine-banded armadillos have short legs with 4 toes on the forefoot and 5 toes on the hindfoot; all toes have strong claws, and the middle claws are largest of all. They have distinct teeth, which are v-shaped, small and peg-like. Their teeth do not have enamal, and they continue to grow throughout the animal's lifetime. Nine-banded armadillos have long, sticky tongues, which they use in foraging for insects. (Chapman and Feldhamer, 1982; Macdonald, 1984; Stangle, 1994)
Males weigh 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). (Atansanov, 2007; Chapman and Feldhamer, 1982; Peppler and Stone, 1981)
Nine-banded armadillos range from Argentina and Uruguay, through Central America and into the southern United States. They have the largest range of any extant species of armadillo. Their range has slowly been expanding northward in the United States, and they are now found as far north as Missouri and even Illinois. This shift northward is likely limited by the severity of cold, winter weather. Their ranges have also been shifting westward in the United States, and this is likely limited by their dependence on rainfall or other sources of water. (Chapman and Feldhamer, 1982; Macdonald, 1984; Van Deelen, et al., 2002; Wilson and Ruff, 1999)
Increasing human populations and development of transportation routes are thought to help the range expansion of nine-banded armadillos. Roads and bridges help wild nine-banded armadillos to move across wide waterways and other natural obstacles that would had previously prevented their expansion. Human activities have also caused a decline in many natural predators of North American nine-banded armadillos, which also contributes to their expanding range. (Chapman and Feldhamer, 1982; Talmage, 1954; Taulman and Robbins, 1996)
Nine-banded armadillos are primarily found in forest and scrub-brush areas in tropical and temperate regions. They are also found in grasslands and savanna regions around woody areas, but they prefer forests over grasslands because they forage in forest litter for small invertebrates. They are not found in arid regions, and they thrive in riparian habitats or areas with plenty of water or at least 38 cm of rain annually. Their preference for wet areas may be because of increased availability of food sources in wet areas and softer soil, which makes 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. ("Dasypus novemcinctus", 2008; Stangle, 1994; Talmage, 1954; Taulman and Robbins, 1996)
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. Nine-banded armadillos are not found in regions where the average January temperature drops below -2°C. Dense populations tend to occur in areas of low elevation, often around sea-level. (Chapman and Feldhamer, 1982; Talmage, 1954; Taulman and Robbins, 1996)
Although nine-banded armadillos do not often inhabit areas of dense human population, they are not limited by human presence. In fact, the northeastern expansion of their range may be related to human development. They appear to travel along man-made roads, bridges, railroads and other travel routes. (Talmage, 1954; Taulman and Robbins, 1996)
Within their habitat in forests, grasslands, and shrublands, nine-banded armadillos 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. 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. (Macdonald, 1984; Stangle, 1994)
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. (McDonough, 1997; Stangle, 1994)
It is thought that a male maintains this close proximity to the female in order to claim and protect her from other males. In some cases, a male is aggressive toward other males to prevent them from breeding with the female he is paired with. Maintaining close proximity may also allow the male to determine when the female is receptive to breeding. Females constantly appear to retreat from males, possibly attempting to prevent males from coming too close before she is ready to mate. Females give off secretions from their anal glands that may change in scent when they are ready to mate. Nine-banded armadillos are thought to be polygynous with respect to pairs (one male pairs with multiple females), but pairing may not lead to mating. (Loughry, et al., 1998; McDonough, 1997)
Most females ovulate once a year, usually in early summer (June to July in the northern hemisphere, November to December in the southern hemisphere). Mating occurs during this time of year, with the female positioned on her back. Females almost always give 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. ("Dasypus novemcinctus", 2008; Chapman and Feldhamer, 1982; Macdonald, 1984; Stangle, 1994)
Young nine-banded armadillos are born in an advanced state of development, closely resembling adults 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 2 years of age. Full development and maturity is attained by 3 or 4 years of age. (Chapman and Feldhamer, 1982; Macdonald, 1984; Stangle, 1994)
Young nine-banded armadillos 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 mothers to not provide significant care at this point. A young nine-banded armadillo may share a burrow and foraging areas with its siblings during its first summer and early fall. ("Dasypus novemcinctus", 2008; Loughry and McDonough, 1994; Stangle, 1994)
Nine-banded armadillos are expected to live from 7 to 8 years to over 20 years in the wild. One nine-banded armadillo in captivity reached 23 years of age. The life of nine-banded armadillos may be limited by climate, predation, and disease. Because they do not have much hair or body fat, nine-banded armadillos do not cope well with cold temperatures. Larger animals can better withstand colder temperatures. Droughts can also impact mortality of this species. Juveniles have a higher mortality rate than adults and in the wild are more likely to be killed by a predator than adults because they are weaker and have softer armor. Disease, particularly leprosy, also contributes to mortality of nine-banded armadillo. (McDonough and Loughry, 1997; McDonough, 1997; Peppler and Stone, 1981; Stangle, 1994; Taulman and Robbins, 1996)
Nine-banded armadillos are nocturnal (foraging at night) or crepuscular (foraging during dawn and dusk) but also 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 hold its breath for up to 6 minutes, but they tire quickly and cannot cross wide bodies of water. (Chapman and Feldhamer, 1982; Moeller, 1990; Schmidly and William, 1994; Wilson and Ruff, 1999)
Nine-banded armadillos dig burrows by loosening soil with their noses and forelimbs and then kick the soil away with their hind limbs. They generally use a main entrance to their burrow, but a burrow may have several entrances. 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 to store food. 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 on their hind legs. Rotting materials may be removed from nests after heavy rainfall. Nine-banded armadillos generally do not share their burrows, except for mating pairs and a mother with her liter. In cold weather, however, adults may share their burrows with non-related adults for warmth. (Chapman and Feldhamer, 1982; McDonough and Loughry, 2008; Moeller, 1990; Schmidly and William, 1994; Wilson and Ruff, 1999)
Nine-banded armadillos are generally unaggressive toward one another, although pregnant or nursing mothers may be unusually aggressive. 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 threatened, 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. (Chapman and Feldhamer, 1982; McDonough and Loughry, 2008; Wilson and Ruff, 1999)
The home range of nine-banded armadillos ranges from 0.63 to 20.1 ha. The size of their home range is affected by he 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. Adults of both sexes may share home ranges with juveniles and members of the opposite sex, though males tolerate less overlap. (Chapman and Feldhamer, 1982; McDonough and Loughry, 2008)
Olfaction, or the sense of smell, is incredibly important to nine-banded armadillos and 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 on their hid legs, bracing themselves with their tail, and sniff the air to locate food. Nine-banded armadillos may also use smell to recognize familiar places and to orient themselves. (Chapman and Feldhamer, 1982; Moeller, 1990)
Nine-banded armadillos also have a good sense of hearing, which they use to avoid predation. Mating pairs also communicate with a “chucking” sound. Nine-banded armadillos have a poor sense of vision 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. (Chapman and Feldhamer, 1982; Moeller, 1990)
Nine-banded armadillos are generalists and eat almost 500 different types of food items. Over 90% of their diet is composed of animal matter. A larger part of their diet is composed of adult and larval beetles, 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 eating these 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. (Chapman and Feldhamer, 1982; Schmidly and William, 1994)
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. Because of their softer armor, juveniles are more susceptible to predation than adults, and this is reflected in their behavior. Young nine-banded armadillos tend to forage earlier in the day and are more cautious of humans than 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. Nine-banded armadillos are hunted in many rural areas for their meat and skin, and auto accidents claim the lives of thousands of individuals each year. (Moeller, 1990; Weckel, et al., 2006; Wilson and Ruff, 1999)
Armadillos, including nine-banded armadillos, are scavengers and consumers of many kinds of invertebrates. They have low body temperatures that they cannot regulate very well because of their carapace. This results in a poor immune system. Thus, nine-banded armadillos are host to a variety of bacterial and protozoan parasites including 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 are commensalists or parasites. (Bagagli and De Moraes Gimenens Bosco, 2008; Cheadle, et al., 2001; Eulalio, et al., 2001; Moeller, 1990; Szabó, et al., 2007)
Fan-tailed warblers have been observed following nine-banded armadillos while they forage, searching for prey revealed by the armadillos’ activities. 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. The carrion of nine-banded armadillos resulting from road kill is becoming an important food source for some species of birds. Nine-banded armadillos were introduced to Florida, where they may prey on endangered endemic Floridian reptiles. In addition, nine-banded armadillos may force Gopherus polyphemus, an endangered Floridian tortoise, from their burrows and claim them for itself. (Chapman and Feldhamer, 1982; Ealy, et al., 2004; Schaefer and Fagan, 2006)
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. (Chapman and Feldhamer, 1982; Moeller, 1990)
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. One well-studied pathogen is the fungus Paracoccidiodies brasiliensis, which is responsible for a widespread mycosis in Brazil. Another is the bacterium Mycobacterium leprae, which causes leprosy. Nine-banded armadillos are important predators of a variety of common insect agricultural pests. In addition, nine-banded armadillos are hunted for their meat and skin, which is used to make various trinkets. (Chapman and Feldhamer, 1982; Moeller, 1990; Schmidly and William, 1994)
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. ("Dasypus novemcinctus", 2008)
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