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Akodon cursorcursor grass mouse

By Lars Higdon

Geographic Range

This species occupies a range from southeastern and central Brazil through Uruguay, Paraguay, and northeastern Argentina. (Redford and Eisenberg , 1992)

Habitat

Akodon cursor is one of the most common species in the forest and forest-grassland ecotones. In Misiones province, Argentina, they are found in a variety of habitats but prefe flat and xeric, semi-deciduous areas. This species also displays spatial partitioning with Akodon montensis. Akodon cursor dominates elevations from 0-800m leaving Akodon montensis to dominate elevations exceeding 800m. Populations of Akodon cursor flourish in dry, open areas with little human influence. (Gentile, 2000; Redford and Eisenberg , 1992; Patton and Smith, 2001)

  • Range elevation
    0 to 800 m
    0.00 to 2624.67 ft

Physical Description

Akodon cursor is a medium sized, vole-like mouse, with short limbs, and a short tail. The pelage is soft and full with a reddish brown to olive brown color dorsally, fading to more of a tan on the sides and gradually becoming a reddish tan to gray washed with orange on the venter. The tail is sparsely haired and almost bicolored. The feet are tan and the face shows some blackish hairs. Juveniles weigh around 30g for females and 28g for males. The sub-adult class contains females ranging from 30g-40g and males ranging from 28g-45g. Adult males weigh around 45g and adult females can weigh greater than 40g. (Gentile, 2000; Redford and Eisenberg , 1992; Nowak, 1999)

  • Sexual Dimorphism
  • male larger
  • Range mass
    40 to 45 g
    1.41 to 1.59 oz

Reproduction

There is little information on mating in Akodon cursor. (Gentile, 2000)

Breeding season is typically from September to March, however, this species will breed year round opportunistically if conditions are right. Reproduction is also tied to habitat availability. During the rainy season habitat is lost to flooding and scarcity of litter and understory. Most births usually occur in dry periods but reproductive patterns are not distinct. As a result most juveniles are present during periods of low precipitation. The litter size is usually three and average gestation time of other Akodon species is 23 days. Young are weaned at about 14 days old in other Akodon species. Akodon cursor will occasionally hybridize with other species of the same genus including Akodon montensis. Many females retain a copulatory plug to indicate they have mated. For males, sexual maturity occurs at 32-37 days old and at 28g. For females, sexual maturity is delayed to around 42 days or at a weight of 30g. Overall, this species has a short life expectancy, short gestation time, and early maturity which results in rapid population turnover and quick responses to environmental variation. Delayed implantation is thought to occur in some species of Akodon and may occur in Akodon cursor as well. (Gentile, 2000; Redford and Eisenberg , 1992; Patton and Smith, 2001)

  • Breeding interval
    Breeding occurs continually during conditions appropriate for breeding, as few as twice yearly or as often as every month.
  • Breeding season
    Breeding typically occurs from September to March, but may occur year-round.
  • Average number of offspring
    3
  • Average gestation period
    23 days
  • Average weaning age
    14 days
  • Average age at sexual or reproductive maturity (female)
    42 days
  • Range age at sexual or reproductive maturity (male)
    32 to 37 days

Young are nursed and cared by their mother for until they are weaned at about 14 days old.

Lifespan/Longevity

There is little information on longevity in Akodon cursor. It is likely that most mortality occurs during their first year and that they are unlikely to reach their third year.

Behavior

Akodon cursor can be territorial. This species also reduces activity in times of low temperatures to conserve heat due to their large surface area to volume ratio. (Gentile and Cerqueira, 1995; Fernandez, et al., 1999; Bittencourt, et al., 1999)

Home Range

This species has shown the greatest frequency of movement from 0-20m away from nest sites with most movements less than 30m away. This indicates a relatively small home range in comparison to other neotropical rodents. Any significant difference between the movement patterns of males and females has not been observed. Lower mobility of Akodon cursor is also paired with higher aggregation and more permanent populations. (Gentile and Cerqueira, 1995)

Communication and Perception

Akodon cursor, like most mammals, relies on a suite of visual, auditory, chemical, and tactile cues for communicating with conspecifics. It is likely that olfactory cues are important in communicating territories and reproductive activity.

Food Habits

Stomach samples from this species have indicated a diverse diet ranging from plant material and seeds to adult and larval coleopterans, lepidopterans, and dipterans. (Redford and Eisenberg , 1992)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • seeds, grains, and nuts

Predation

Akodon cursor blends well with it's environment and utilizes ground cover and brush to hide from predators. A variety of raptors and carnivores feed on this species. (Redford and Eisenberg , 1992)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Akodon cursor is a mouse that typically occurs in great abundance in open, dry areas. It often preys on small insects and plant material. It may also disperse seeds that are ingested as food. This species also acts as food for larger mammals, snakes, and raptors. (Redford and Eisenberg , 1992; Nowak, 1999)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Despite the reputation of rodents to damage crops, this has not been observed in this species. The diet of this species, which includes insects, may actually help reduce farm pests and crop damage. (Gentile, 2000)

Economic Importance for Humans: Negative

There are no known negative impacts of Akodon cursor on humans.

Conservation Status

Akodon cursor is abundant in appropriate habitats, they are not protected under CITES or IUCN.

Other Comments

A recent study has shown that females of this species have exhibited an XY chromosome combination in 10-66% of samples. Sex ratio of males to females is typically 1:1. (D'Andrea, et al., 1999; Patton and Smith, 2001)

Contributors

Lars Higdon (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.

Glossary

Neotropical

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

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

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.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

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.

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.

female parental care

parental care is carried out by females

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

omnivore

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

scrub forest

scrub forests develop in areas that experience dry seasons.

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

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

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

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Bittencourt, E., C. Vera Y Conde, C. Rocha, H. Bergallo. 1999. Activity Patterns of Small Mammals in an Atlantic Forest Area of Southwest Brazil. Ciencia e Cultura, 51/2: 126-132.

D'Andrea, P., R. Gentile, R. Cerqueira, C. Grelle, C. Horta. 1999. Ecology of SMall Mammals in a Brazilian Rural Area. Revista Brasileira de Zoologia, 16/3: 611-620.

Fernandez, F., S. Freitas, R. Cerqueira. 1999. Density Dependence in Within-Habitat Spatial Distribution: Contrasting Patterns for a Rodent and a Marsupial in Southeastern Brazil. Ciencia e Cultura, 49/1-2: 127-129.

Gentile, R. 2000. Population Dynamics and Reproduction of Marsupials and Rodents in a Brazilian Rural Study: A Five Year Study. Studies on Neotropical Fauna and Environment, 35: 1-9.

Gentile, R., R. Cerqueira. 1995. Movement Patterns of Five Species of Small Mammals in Brazilian Restinga. Journal of Tropical Ecology, 14/4: 671-677.

Nowak, J. 1999. Walker's Mammals of the World. Baltimore: Johns Hopkins University Press.

Patton, J., F. Smith. 2001. Diversification in the Genus Akodon(Rodentia: Sigmodontiane) in Southeastern South America: Mitochondrial DNA Sequence Analysis. Journal of Mammalogy, 82: 92-101.

Redford, K., J. Eisenberg . 1992. Mammals of the Neotropics. Chicago: University of Chicago Press.

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