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Dasypus septemcinctusseven-banded armadillo

By Jeremy Fruk

Geographic Range

The distribution of seven-banded armadillos Dasypus septemcinctus is limited to the South American Continent. Their geographical range in the neotropical region extends from the lower Amazonian Basin of Brazil to the Gran Chaco of Bolivia, Paraguay and northern provinces of Argentina: Salta, Formosa, and Chaco. (Redford and Eisenberg, 1989; Wilson and Reeder, 2005)

Habitat

Seven-banded armidillos inhabit grasslands, with the exception of southeastern Brazil, where they can be found in the gallery forests. (Redford and Eisenberg, 1989)

Physical Description

The most distinct physical characteristic of armadillos, Dasypodidae, is the carapace that resembles gray or brown armor. The carapace is made of ossified dermal plates that resemble a thick hardened skin. The majority of an armadillo's body is covered with the carapace, with the exception of the abdomen region. Seven-banded armadillos have thick-skinned abdomens with hair yellow and/or white in appearance. The carapace itself is divided into three sections: a scapular shield, a pelvic shield, and a series of bands around the midsection. Seven-banded armadillos have 6 to 8 bands located in the midsection of the carapace. Nine-banded armadillos, Dasypus novemcinctus, a close relative to the seven-banded armadillo, have 7 to 11 bands. (Fox, 1999; Hamlett, 1939; Redford and Eisenberg, 1989; Walker, 1975)

Nine-banded armadillos, are similar in appearance to seven-banded armadillos, though nine-banded armadillos are larger in body size and typically have two more bands in the midsection of the carapace. Seven-banded armadillos are the smallest of g. Dasypus with an average mass of 1.63 kg. Head and body length averages 269 mm while the tail measures an additional 147 mm. Seven-banded armadillos have 4 digits on their forefeet and 5 digits on their hind feet. The ears are about half the size of their head, and they have a long flattened snout used to forage for insects. (Fox, 1999; Hamlett, 1939; Redford and Eisenberg, 1989; Walker, 1975)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    1.47 kg
    3.24 lb
  • Average length
    416 mm
    16.38 in

Reproduction

Little information is available regarding mating systems of seven-banded armadillos. However, their close relatives, nine-banded armadillos, exhibit a polygynous mating system where the male mates with more than one female. The male entices the female for courtship by marking an area with urine. The female then responds by lying on her back to initiate copulation. The male and female may briefly share a den after copulation. (Davis and Schimidly, 1997; Loughry, et al., 1998a; Voelker, 1986)

Little information for the breeding season of seven-banded armadillos is available, though it is likely similar to that of close relatives nine-banded armadillos. Nine-banded armadillos begin breeding in July and in rare occurrences extend the breeding season until December. Female seven-banded armadillos reach sexual maturity around 274 days of age. The gestation period for seven-banded armadillos is reported to be 132 days and varies little to the gestation period of 135 days for nine-banded armadillos. While gestation periods for seven-banded and nine-banded armadillos may last a little over 130 days, the pregnancy may last for an additional 120 days due to females' ability to delay implantation. Delayed implantation occurs in all members of g. Dasypus and results from the blastocyst remaining unattached in the uterus while allowing oxygen and nutrition to be released from uterine secretions. Delayed implantation usually occurs for three months after fertilization and may result from environmental stress. Davis and Schmimidly (1997) state that delayed implantation may help the young of g. Dasypus avoid stressful conditions and increase their chances of survival. When implantation occurs in seven-banded armadillos, the blastocyst divides to form 6 to 8 distinct embryonic growth centers, which attach to the uterus by a shared placenta. This process is called polyembryony and results in a litter of 6 to 8 identical offspring. Seven-banded armadillos frequently have litter sizes of 6-8 young, even though all members of g. Dasypus have four teats. Litter sizes are smaller for nine-banded armadillos as they consistently have a litter of four identical quadruplets to complement the number of teats. After implantation occurs for nine-banded armadillos, a litter is born fully formed with eyes opening in approximately 4 months. The young can begin to walk within hours of birth and forage with their mother within a few weeks. They are reported to wean within 2 months but may remain with their mother for a few more months. The young are then capable of breeding in the early summer of the following year. ("AnAge Entry for Dasypus septemcinctus", 2009; Davis and Schimidly, 1997; Redford and Eisenberg, 1989; Smith and Doughty, 1984; Walker, 1975)

  • Breeding interval
    Breeding patterns of seven-banded armadillos are likely similar to that of nine banded armadillos, which breed yearly.
  • Breeding season
    Breeding patterns of seven-banded armadillos are likely similar to that of nine banded armadillos, which breed during early summer.
  • Range number of offspring
    4 to 12
  • Average number of offspring
    4 to 6
  • Average gestation period
    132 days
  • Average age at sexual or reproductive maturity (female)
    274 days

Little information is available regarding parental investment of seven-banded armadillos.

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

Lifespan/Longevity

The maximum lifespan reported for one specimen of seven-banded armadillos in captivity was observed to be 16.8 years. Other information is limited in availability. ("AnAge Entry for Dasypus septemcinctus", 2009)

  • Range lifespan
    Status: captivity
    16.8 (high) years

Behavior

Seven-banded armadillos are an asocial diurnal species that commonly take advantage of burrows made from other species and expand these burrows by digging horizontally anywhere from four to twelve feet. They usually have multiple burrows and join these to a central den. When seven-banded armadillos are not in their burrows, they are foraging in grasslands and gallery forests with their snout close to the ground. While foraging, they use their sense of smell to prey on insects and other small animals. When pursued they retreat to a burrow and wedge themselves against it making it difficult for predators to remove them from their burrow. (Carter and Encarnaçao, 1983; Hamlett, 1939; Redford and Eisenberg, 1989; Walker, 1975)

Home Range

There is little available information on home range for seven-banded armadillos.

Communication and Perception

Little information is available regarding communication and perception of seven-banded armadillos, but their close relative nine-banded armadillos have poor eyesight and therefore rely on their keen sense of smell. This sense of smell allows them to efficiently forage under leaf and grass litter. Olfactory senses are also used for mate selection and sibling recognition. (Fox, 1999; Loughry, et al., 1998b; Smith and Doughty, 1984)

Food Habits

Seven-banded armadillos are generally considered insectivores, although they could also be considered slightly omnivorous as they occasionally eat plants and other types of animal foods. Their diet mainly consists of insects such as ants, beetles, wasps, caterpillars, roaches, termites, and larvae. They may also eat other organisms such as small reptiles, amphibians, and even bird carcasses. (Redford and Eisenberg, 1989; Smith and Doughty, 1984; Walker, 1975)

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

Predation

Little information is available regarding predation of seven-banded armadillos. When pursued, seven-banded armadillos usually run and wedge themselves in a burrow ensuring their abdomen region is protected from predation. Seven-banded armadillos are not hunted by humans as heavily as nine-banded armadillos because of their small size. (Anacleto, et al., 2006; Smith and Doughty, 1984; Walker, 1975)

Ecosystem Roles

Seven-banded armadillos are scavengers, consuming a wide variety of invertebrates as well as carrion and occasionally plants. Primarily insectivorous, seven-banded armadillos control insect populations. (Walker, 1975)

Economic Importance for Humans: Positive

Seven-banded armadillos consume vast amounts of termites and other insects considered as pests to humans. They are also used as subjects for leprosy medical research. (Redford and Eisenberg, 1989; Walker, 1975; Redford and Eisenberg, 1989; Walker, 1975; Redford and Eisenberg, 1989; Smith and Doughty, 1984; Walker, 1975)

Economic Importance for Humans: Negative

Seven-banded armadillos may burrow underneath manmade structures causing supporting soils to become instable. (Redford and Eisenberg, 1989; Smith and Doughty, 1984; Walker, 1975)

  • Negative Impacts
  • household pest

Conservation Status

Seven-banded armadillos are listed on the IUCN Red List as least concern

Contributors

Jeremy Fruk (author), Northern Michigan University, John Bruggink (editor), Northern Michigan University, Gail McCormick (editor), Animal Diversity Web Staff.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

diurnal
  1. active during the day, 2. lasting for one day.
drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

insectivore

An animal that eats mainly insects or spiders.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

polygynous

having more than one female as a mate at one time

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

References

2009. "AnAge Entry for Dasypus septemcinctus" (On-line). An Age:The Animal Ageing and Longevity Database. Accessed March 13, 2009 at http://genomics.senescence.info/species/entry.php?species=Dasypus_septemcinctus.

Anacleto, T., J. Diniz-Filho, M. Vital. 2006. Estimating potential geographic ranges of armadillos (Xenarthra, Dasypodidae) in Brazil under niche-based models. Mammalia, 70: 202-213.

Carter, T., C. Encarnaçao. 1983. Characteristics and use of burrows by four species of armadillos in Brazil. Journal of Mammalogy, 64: 103-108.

Davis, W., D. Schimidly. 1997. "Nine-banded Armadillo" (On-line). The Mammals of Texas - Online Edition. Accessed March 12, 2009 at http://www.nsrl.ttu.edu/TMOT1/dasynove.htm.

Fox, D. 1999. "Dasypus novemcinctus" (On-line). Animal Diversity Web. Accessed March 16, 2009 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasypus_novemcinctus.html..

Hamlett, G. 1939. Identity of Dasypus septemcinctus Linnaeus with notes on some related species. Journal of Mammology, 20: 328-336.

Loughry, W., P. Prodohl, C. Mcdonough, W. Nelson, J. Avise. 1998. Correlates of reproductive success in a population of nine-banded armadillos. Canadian Journal of Zoology, 76: 1815-1821.

Loughry, W., G. Dwyer, C. Mcdonough. 1998. Behavioral interactions between juvenile nine-banded armadillos (Dasypus novemcinctus) in staged encounters. American Midland Naturalist, 139: 125-132.

Redford, K., J. Eisenberg. 1989. Mammals of the Neotropics, Volume 2, The Southern Cone: Chile, Argentina, Uruguay, Paraguay. Chicago: University Chicago Press.

Smith, L., R. Doughty. 1984. The Amazing Armadillo: Geography of a Folk Critter. Austin Texas: University of Texas Press.

Voelker, W. 1986. The Natural History of Living Mammals. Medford, NJ: Plexus Publishing, Inc.

Walker, E. 1975. Dasypus septemcinctus. Pp. 501-503 in J Paradiso, ed. Mammals of the World, Vol. 1, 3 Edition. Baltimore and London: John Hopkins University Press.

Wilson, E., D. Reeder. 2005. "Mammal species of the world. A Taxonomic and Geographic Reference 3rd ed." (On-line). Wilson & Reeder's Mammal Species of the World. Accessed March 11, 2009 at http://www.bucknell.edu/MSW3.

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