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. (Bilenca and Kravetz, 1998; Bonaventura and Kravetz, 1989; Busch, et al., 2001; Macdonald, 2001; Nowak, 1997; Suarez and Bonaventura, 2001)is found at altitudes from sea level to approximately 5,000 meters.
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. (Dalby, 1975; Nowak, 1997; Redford and Eisenberg, 1992)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.
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. (Busch and Del Valle, 2003; Suarez and Kravetz, 1998)
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. (Zuleta and Bilenca, 1992)
When building homes, members of this species prefer burrow nests to be underground rather than at the surface. If individuals do have a surface nest, it is cup-shaped with sides and a cover and usually 8 to 10 cm in diameter. The structure of the burrow system often includes a branch leading to a single nest chamber packed with dry grasses. Sometimes, seeds and dry grasses are included in the central chamber. The selection of borders for burrowing can be significant. Most of the daily activities and reproductive sites depend on the presence of good plant cover and characteristics of the soil. (Hodara, et al., 1997)
The home range of females is constant, whereas that of males is variable. During the breeding season, the home range of males is twice the size of females. It is also believed that the range for sexually active males is greater than the range of non-active males. Activity peaks are often found during twilight and early evening hours. And homing is so well developed in the species that even after being displaced 100 meters away, (Dalby, 1975; Zuleta and Bilenca, 1992)can return to its home.
Information pertaining to the communication used bywas 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.
Other information pertaining to its impact on the ecosystem was not available. However, because of its preference for seeds and fruits, one may presume thatdisperses 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.
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.
The IUCN Red List listsas lower risk, least concern. The US Federal List and CITES indicate that is not a particular conservation concern, and the species has no special status witht hese organizations.
Nancy Shefferly (editor), Animal Diversity Web.
Mika Matthews (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
living in landscapes dominated by human agriculture.
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.
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.
uses smells or other chemicals to communicate
in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.
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.
union of egg and spermatozoan
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
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).
marshes are wetland areas often dominated by grasses and reeds.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
an animal that mainly eats all kinds of things, including plants and animals
having more than one female as a mate at one time
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
digs and breaks up soil so air and water can get in
uses touch to communicate
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
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.
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.
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.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
young are relatively well-developed when born
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