Necromys lasiurushairy-tailed akodont(Also: hairy-tailed bolo mouse)

Geographic Range

Necromys lasiurus (hairy-tailed bolo mouse) is distributed throughout central South America. Their range extends from Brazil and Paraguay to Bolivia and into the northern Argentine province of Misiones. (Redford and Eisenberg, 1992; Redford and Eisenberg, 1999)


Hairy-tailed bolo mice are usually found in grassland or savanna habitats. In Brazil, they can be found in the Cerrado, the regional name giveg to the Brazilian savannas or the Caatinga in the northeastern part of Brazil. They may sometimes be found in forests, typically inhabiting the area near the edges. Occasionally hairy-tailed bolo mice are known to reside in cultivated or abandoned fields. (Cangussu, et al., 2002; Henriques and Alho, 1991; Redford and Eisenberg, 1992; Redford and Eisenberg, 1999)

Physical Description

Hairy-tailed bolo mice are an olive-gray color with a lighter grayish white color on their belly, although the fur color does vary slightly according to geographic range. Aside from the lighter belly, they are uniformly colored. They have short ears, small eyes, and their hind feet are somewhat darker than their backs. They lack any distinctive facial markings. Their tail, for which they are named, is shorter than the length of their head and body and is lightly haired. On average, the head and body of the mice measures around 103 mm and the tail measures 75 mm. The average weight is 35 g. There is slight sexual dimorphism in that males sre larger than the females. (Cangussu, et al., 2002; Redford and Eisenberg, 1992; Redford and Eisenberg, 1999)

  • Sexual Dimorphism
  • male larger
  • Average mass
    35 g
    1.23 oz
  • Average length
    178 mm
    7.01 in


Although there have been many studies on the reproduction of this species, there is little information on the mating systems of hairy-tailed bolo mice.

Reproductive activity of hairy-tailed bolo mice increases during the rainy seasons (January to March) compared to the dry seasons (July to September). Reproductive rate probably follows rainfall because rainfall affects food availability, growth of vegetation, and the probability of fire. Although the peak in reproductive rate occurs during the rainy season, there is also high reproductive activity in the late dry season from October to November. Hairy-tailed bolo mice also produce more than one time a year and on average have 3-6 young per litter. (Cangussu, et al., 2002; Francisco, et al., 1995; Redford and Eisenberg, 1992; Redford and Eisenberg, 1999)

  • Breeding interval
    Multiple times a year
  • Breeding season
  • Average number of offspring

Little is known about the parental investment provided by hairy-tailed bolo mice but in related species of mice in the family Muridae offspring are altricial and the mother provides most of the parental care. ("Animal Diversity Web", 2004)

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


Although Necromys lasiurus is fairly well studied, the lifespan of this mouse is unknown.


There is not much information about the behavior of hairy-tailed bolo mice. What is known is that they are terrestrial, sometimes active during the day, and they dig and live in burrows. They build nests from grass, leaves, and other such debris. They live in burrows underground with multiple openings and tunnels. (Magnusson, et al., 1995; Redford and Eisenberg, 1992; Redford and Eisenberg, 1999)

Home Range

Home ranges differ between males and females: female home ranges being approximately 35% the area of male home ranges. The average home range size for males is from 4138-21880 m^2 while for females the range is from 1317-5480 m^2. Female home ranges tend to be exclusive while males tend to overlap with females' ranges. The most likely reason for this difference as well as the difference in range sizes between sexes is that females can maximize their reproductive potential by defending their food source while males can benefit by coming into contact with as many females as possible. (Magnusson, et al., 1995)

Communication and Perception

There is little known about the communication among hairy-tailed bolo mice. There is also little information about the perception channels used by these mice but they probably rely heavily on their sense of touch and smell as opposed to vision. (Redford and Eisenberg, 1992)

Food Habits

Hairy-tailed bolo mice are primarily granivores, with 82% of their diet consisting of seeds. Such a large dependence on seeds can be a problem, especially when fires at the end of the dry season affect the vegetation and seed sources. This may be part of why there are such a large fluctuations in population size related to seed production. As a result of the fires, the mice show an increased dependence on invertebrates or insects during the following rainy season. (Feliciano, et al., 2002; Francisco, et al., 1995; Magnusson, et al., 1995; Redford and Eisenberg, 1992)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • seeds, grains, and nuts


While there is little written about the predators of hairy-tailed bolo mice, there is no doubt that predation on these animals is strong, as in other small rodents.

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Hairy-tailed bolo mice play an important role in the ecosystem as seed dispersers. They are also a food source for their predators. (Francisco, et al., 1995; Redford and Eisenberg, 1992)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Little is known about the economic importance of hairy-tailed bolo mice for humans.

Economic Importance for Humans: Negative

Like most mice, hairy-tailed bolo mice are known to carry diseases and parasites. They may also damage some crops if they are living in cultivated fields. (Redford and Eisenberg, 1992)

  • Negative Impacts
  • injures humans
    • carries human disease
  • crop pest

Conservation Status

At this time, hairy-tailed bolo mice are not threatened and they are under no special status on IUCN Red List and CITES. ("2003 IUCN Red List of Threatened Species", 2003; "Convention on International Trade in Endagered Species of Wild Fauna and Flora", 2004)

Other Comments

Hairy-tailed bolo mice have also be known as Bolomys lasiurus, Akodon lasiurus, A. arviculoides, A. lenguarum, Necromys lasiurus, Cabreramys lasiurus, and Zygodontomys lasiurus. (Redford and Eisenberg, 1992; Redford and Eisenberg, 1999)


Matthew Wund (editor), University of Michigan-Ann Arbor.

Shivani Raval (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.

World Map


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.

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.


uses smells or other chemicals to communicate


active at dawn and dusk


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.

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

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.


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


an animal that mainly eats seeds


An animal that eats mainly plants or parts of plants.


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).


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.


active during the night

seasonal breeding

breeding is confined to a particular season


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


lives alone


uses touch to communicate


Living on the ground.


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


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.


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.


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.


2003. "2003 IUCN Red List of Threatened Species" (On-line). Accessed April 01, 2004 at

2004. "Animal Diversity Web" (On-line). Accessed April 01, 2004 at

2004. "Convention on International Trade in Endagered Species of Wild Fauna and Flora" (On-line). Accessed April 01, 2004 at

Alho, C., L. Pereira. 1985. Population ecology of a cerrado rodent community in Central Brazil. Revista Brasileira de Biologia, 45(4): 597-608.

Botelho, J., P. Linardi. 1996. Interrelationships between ectoparasites and rodents in wild and urban environments at Belo Horizonte, Minas Gerais State, Brazil. Revista Brasileira de Entomologia, 40(3-4): 425-430.

Cangussu, S., F. Vieira, R. Rossoni. 2002. Sexual Dimorphism and Seasonal Variation in Submandibular Glad Histology of Bolomys lasiurus (Rodentia, Muridae). Journal of Morphology, 254: 320-327.

De Oliveira, J., R. Strauss, S. Dos Reis. 1998. Assessing relative age and age structure in natural populations of Bolomys lasiurus (Rodentia: Sigmodontinae) in northeastern Brazil. Journal of Mammalogy, 79(4): 1170-1183.

Dietz, J. 1983. The Natural History of Some Small Mammals in Central Brazil. Journal of Mammalogy, Volume 64 Number 3: 521-523.

Feliciano, B., F. Fernandez, D. De Freitas, M. Figueiredo. 2002. Population dynamics of small rodents in a grassland between fragments of Atlantic Forest in southeaster Brazil. Mammalian Biology, 67(5): 304-314.

Francisco, A., W. Magnusson, T. Sanaiotti. 1995. Variation in growth and reproduction of Bolomys lasiurus (Rodentia: Muridae) in an Amazonian savanna. Journal of Tropical Ecology, 11: 419-428.

Henriques, R., C. Alho. 1991. Microhabitat Selection by Two Rodent Species in the Cerrado of Central Brazil. Mammalia, 55(1): 49-56.

Macedo, R., M. Mares. 1987. Geographic variation in the South American cricetine rodent Bolomys lasiurus. Journal of Mammalogy, 68(3): 578-594.

Magnusson, W., A. Francisco, T. Sanaiotti. 1995. Home-range size and territoriality in Bolomys lasiurus (Rodentia: Muridae) in an Amazonian savanna. Journal of Tropical Ecology, 11: 179-188.

Parreira, G., F. Cardoso. 1993. Seasonal variation of the spermatogenic activity in Bolomys lasiurus (Lund, 1841) (Rodentia, Cricetidae), from southeaster Brazil. Mammalia, 57(1): 27-34.

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Redford, K., J. Eisenberg. 1992. Mammals of the Neotropics: The Southern Cone, Volume 2. Chicago: The University of Chicago Press.

Scheibler, D., J. Menegheti, A. Christoff. 2001. Predation of Elanus leucurus (Aves, Accipitridae) on Mus musculus (Mammalia, Muridae) and its temporal variation in agroecosystem of the Venancio Aires country, Rio Grande do Sul state, Brazil. Boletin de la Sociedad de Biologia de Concepcion, 72: 125-130.

Talamoni, S., M. Dias. 1999. Population and community ecology of small mammals in southeastern Brazil. Mammalia, 63(2): 167-181.

Vieira, E. 1999. Small mammal communities and fire in the Brazilian Cerrado. Journal of Zoology, 249(1): 75-81.

Vieira, E., L. Baumgarten. 1995. Daily activity patterns of small mammals in a cerrado area from central Brazil. Journal of Tropical Ecology, 11(2): 255-262.

Vieira, M. 2003. Seasonal niche dynamics in coexisting rodents of the Brazilian cerrado. Studies on Neotropical Fauna & Environment, 38(1): 7-15..