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Reproduction

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A. azarae has a polygynous mating system. Even though female Pampean grassland mice mate with only one male during the mating season, a male mates with numerous females. T on reproductive success for males and females. Success for a female is determined by her ability to get green cover and find insects, whereas a male’s success depends upon his ability to copulate with females.

Mating System: polygynous

The breeding season for A. azarae lasts approximately 8 months, beginning in the South American spring (September or October) and ending in autumn (April or May). During the winter, there is a greater abundance of food. Because of this, a female that becomes pregnant during the winter is healthier than one that becomes pregnant during any other season. Although delayed implantation may occur, gestation usually lasts 22.7 days. A female typically produces a litter twice per year, with an average of 3.5 pups per litter. Litter size is positively correlated with the mother’s weight. Birth season also influences litter size. For litters that are conceived at the beginning or end of the mating season, the number of embryos tends to be lower than those conceived in the summer.

A newborn pup on average weighs 2.2 g. It is cared for and weaned by its mother at 14 to 15 days. pups reach sexual maturity and begin breeding at 2 months. A. azarae is generally reproductively active during the same season in which it is born. However, if a pup is not 2 months old by the last days of February or the first few days of March, it will not be mature enough to breed until the following breeding season.

Breeding interval: Azara's grass mice breed twice per year.

Breeding season: The breeding season lasts from September to May.

Average number of offspring: 3.5.

Average gestation period: 22.7 days.

Average weaning age: 14-15 days.

Average age at sexual or reproductive maturity (female): 2 months.

Average age at sexual or reproductive maturity (male): 2 months.

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

During pregnancy and lactation, a female expends a lot of energy--about 159-200% of her basal metabolic rate. She is the only parent that ensures growth and survival of her litter. While caring for the litter, a female teaches her pups which foods they should eat. Pups learn about the food their mother ingested by investigating her mouth.

Mothers actively control the sex ratio of their litters. They do this by committing infanticide of pups. In general, a mother that is in good condition will wean more males, whereas a mother in poor condition will wean more females. This is reflected in the male bias of summer offspring.

Parental Investment: no parental involvement; altricial ; precocial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)

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Matthews, M. 2004. "Akodon azarae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Akodon_azarae.html
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Mika Matthews, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Nancy Shefferly, Animal Diversity Web
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Behavior

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Information pertaining to the communication used by A. azarae was not available. However, it is reasonable to assume that the species probably uses means of communication similar to those used by other small rodents. It is likely that there is some vocal communication. Tactile communication undoubtedly occurs between mothers and their offspring, as well as between mates. Some scent cues may be important to these animals. Visual signals, such as body postures, are often used by small mammals.

Perception Channels: visual ; tactile ; acoustic ; chemical

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Matthews, M. 2004. "Akodon azarae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Akodon_azarae.html
author
Mika Matthews, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Nancy Shefferly, Animal Diversity Web
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Conservation Status

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The IUCN Red List lists A. azarae as lower risk, least concern. The US Federal List and CITES indicate that A. azarae is not a particular conservation concern, and the species has no special status witht hese organizations.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

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Matthews, M. 2004. "Akodon azarae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Akodon_azarae.html
author
Mika Matthews, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
editor
Nancy Shefferly, Animal Diversity Web
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Benefits

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A. azarae is known to carry two hantaviruses: Maciel and Pergamino. These viruses can be transitted to humans, and can result in hemorrhagic fever with renal syndrome or hantavirus pulmonary syndrome. Hantavirus pulmonary syndrome is a cardiopulmonary disease that is very severe and often fatal. Larger and reproductively active males have higher rates of seroprevalence. This can be attributed to their larger home ranges in comparison to the females. This species can also be a crop pest.

Negative Impacts: injures humans (carries human disease); crop pest

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Matthews, M. 2004. "Akodon azarae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Akodon_azarae.html
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Mika Matthews, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Nancy Shefferly, Animal Diversity Web
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Benefits

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There is no indication that this species has a positive effect on humans, and no information on this topic was available in the literature examined.

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Matthews, M. 2004. "Akodon azarae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Akodon_azarae.html
author
Mika Matthews, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
editor
Nancy Shefferly, Animal Diversity Web
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Associations

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A. azarae is used as a host by a variety of mites. Some commensal species that use Azara’s grass mice are Androlaelaps fahrenholzi, Mysolaelaps microspinosus, and Androlaelaps rotundus. Studies have also found these mice to be infested by cuterebrid larvae.

Other information pertaining to its impact on the ecosystem was not available. However, because of its preference for seeds and fruits, one may presume that A. azarae disperses seeds in its surrounding area while feeding. It is also likely that it aerates the soil as it burrows, and affects populations of insects and plants upon which it feeds.

Ecosystem Impact: disperses seeds; soil aeration

Commensal/Parasitic Species:

  • Androlaelaps fahrenholzi
  • Mysolaelaps microspinosus
  • Androlaelaps rotundus
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Matthews, M. 2004. "Akodon azarae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Akodon_azarae.html
author
Mika Matthews, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Nancy Shefferly, Animal Diversity Web
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Trophic Strategy

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A. azarae is a successful omnivore. Its diet consists of green vegetation, fruits, insects, and seeds. Since the species often moves with the change of seasons, its seasonal diet depends on the food that is available and its mother’s physiological condition (due to social learning earlier in its life). These mice ofen eat invertebrates and seeds in the summer, whereas in the winter they feed on plants. Also, females tend to eat more insects when they are available, increasing their of proteins needed to support pregnancy and lactation.

Animal Foods: insects; terrestrial non-insect arthropods

Plant Foods: leaves; seeds, grains, and nuts; fruit

Primary Diet: omnivore

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Matthews, M. 2004. "Akodon azarae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Akodon_azarae.html
author
Mika Matthews, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Nancy Shefferly, Animal Diversity Web
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Distribution

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Akodon azarae is a neotropical species, and is distributed widely across central and southern America. The species range includes Bolivia, Paraguay, Uruguay, and the pampas grasslands from Central Argentina to Southern Brazil.

Biogeographic Regions: neotropical (Native )

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Matthews, M. 2004. "Akodon azarae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Akodon_azarae.html
author
Mika Matthews, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Nancy Shefferly, Animal Diversity Web
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Habitat

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The species prefers borders because of the shelter they provide year-round. For example, in the low Delta of Buenos Aires, it prefers habitats that have high herbaceous cover. This is often because of the protection the cover provides from predators. Seasons also influence the areas it prefers. In the winter, the species prefers low and often temporarily flooded areas. However, in the summer and autumn, it prefers elevated roadsides that have been built along ditches. A. azarae is found at altitudes from sea level to approximately 5,000 meters.

Range elevation: 0 to 5000 m.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: savanna or grassland

Wetlands: marsh

Other Habitat Features: agricultural

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Matthews, M. 2004. "Akodon azarae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Akodon_azarae.html
author
Mika Matthews, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
editor
Nancy Shefferly, Animal Diversity Web
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Life Expectancy

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A. azarae is short lived, and expected lifespan varies based upon the season of birth. Individuals born in the fall have a lifespan of 10 to 12 months, whereas those born in the spring have a lifespan of 7 to 8 months. A limiting factor in the survival these animals is shelter that is available during the winter. Even though it does not affect immigration rates, shelter does affect the survival of those exposed to the harsh weather. Other reasons for disparities are differences in body mass and physical conditions.

Typical lifespan
Status: wild:
7 to 12 months.

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bibliographic citation
Matthews, M. 2004. "Akodon azarae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Akodon_azarae.html
author
Mika Matthews, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
editor
Nancy Shefferly, Animal Diversity Web
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Morphology

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A. azarae is a small mammal, averaging 19 g body mass. Weight varies seasonally, and is at its highest in the spring, decreasing over the following months and then increasing in the winter. The length of the head and body range between 75 and 150 mm, and the tail length is between 50 and 100 mm. These mice have short limbs, and have been described as “vole-like”. The fur is soft and olive brownish dorsally, with a yellowish white tint on the ventrum. The shoulders and nose are reddish brown, and there is a faint eye ring. A female A. azarae has 8 mammae.

A. azarae has a simple stomach. It has a basal metabolic rate of 1.18 to 2.26 cm^3 oxygen/hour. Its average body temperature is 36.14°C. A. azarae does not enter torpor.

Range mass: 10 to 45 g.

Average mass: 19 g.

Range length: 125 to 240 mm.

Range basal metabolic rate: 1.18 to 2.26 cm3.O2/g/hr.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

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bibliographic citation
Matthews, M. 2004. "Akodon azarae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Akodon_azarae.html
author
Mika Matthews, University of Michigan-Ann Arbor
photographer
Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
editor
Nancy Shefferly, Animal Diversity Web
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Associations

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Total plant cover and the height of vegetation determine protection from avian predators. Owls are common predators.

Known Predators:

  • barn owls (Tyto alba)
  • short-eared owls (Asio flammeus)
  • burrowing owls (Athene cunicularia)
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bibliographic citation
Matthews, M. 2004. "Akodon azarae" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Akodon_azarae.html
author
Mika Matthews, University of Michigan-Ann Arbor
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Phil Myers, Museum of Zoology, University of Michigan-Ann Arbor
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Nancy Shefferly, Animal Diversity Web
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Akodon azarae

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Akodon azarae, also known as Azara's akodont[2] or Azara's grass mouse,[1] is a rodent species from South America. It is found from southernmost Brazil through Paraguay and Uruguay into eastern Argentina.[2] It is named after Spanish naturalist Félix de Azara.

References

  1. ^ a b D'Elia and Pardinas, 2008
  2. ^ a b Musser and Carleton, 2005, p. 1093
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Akodon azarae: Brief Summary

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Akodon azarae, also known as Azara's akodont or Azara's grass mouse, is a rodent species from South America. It is found from southernmost Brazil through Paraguay and Uruguay into eastern Argentina. It is named after Spanish naturalist Félix de Azara.

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