Neacomys spinosusbristly mouse

Geographic Range

Common Neacomys, or common bristly mice (Neacomys spinosus) are found in the Amazon Basin of South America, throughout southern Columbia, eastern Peru, western Brazil, and northern Bolivia. (Pardiñas and Patton, 2015)


Common neacomys are found in lowland evergreen rainforests and mid-montane forests, at elevations ranging from 300 to 2,000 m. (Hurtado and Pacheco, 2017)

  • Range elevation
    300 to 2,000 m
    984.25 to ft

Physical Description

Common neacomys are large rats. Their body and head lengths can range from 75 to 105 mm, with grooved spine hairs, large hind feet, reddish to dark brown dorsal fur, pale ventral fur, and tails that are equal to or longer than the rest of their bodies. Three subspecies of Neacomys spinosus have been recognized, including N. s. amoenus, N. s. carceloni, and N. spinosus spinosus itself. Average masses of common neacomys are not known, but other members of the family Cricetidae range from 8 g to 2 kg. (Lawrence, 1941; Pardiñas and Patton, 2015)

  • Range length
    75 to 105 mm
    2.95 to 4.13 in


Nothing is noted of the mating system of common neacomys, however other members of the family Crecetidae can be monogomous, polygynous, or polyandrous.

Pregnant common neacomys females have been caught in both wet (February) and dry (September) seasons, suggesting they possibly have a year-long breeding season. Generational lengths for common neacomys are approximately 1 to 2 years. Typical litter sizes range from 2 to 4 pups. No other information about mating or reproduction in common neacomys is available. (Hice and Velazco, 2013; "International Union for Conservation of Nature", 2016)

  • Breeding season
    Year round
  • Range number of offspring
    2 to 4
  • Range age at sexual or reproductive maturity (female)
    1 to 2 years
  • Range age at sexual or reproductive maturity (male)
    1 to 2 years

Parental investment has not been documented for common neacomys, but other female cricetids (family Cricetidae) raise offspring in nests and feed them milk until they are independent.

  • Parental Investment
  • altricial
  • pre-independence
    • provisioning
      • female


Nothing is noted of the lifespan of common neacomys, but other cricetids typically live a year or less due to predation.


Common neacomys are nocturnal. More research is needed to determine to what degree they are social. It is not known if they remain in the same area or if they migrate to other spaces around the Amazon Basin. ("International Union for Conservation of Nature", 2016)

Home Range

An average home range for common neacomys is not known, and typical home range size varies between other species of cricetids.

Communication and Perception

No information on the communication methods of common neacomys are known, but other cricetids use chemical signaling, and are known to use tactile, visual, and auditory cues.

Food Habits

Common neacomys are omnivores, feeding on seeds, insects and fruits. Specific seeds, insects and fruits selected by common neacomys have not been documented. ("International Union for Conservation of Nature", 2016)


No predators of common neacomys are specifically listed, but other members of the order Rodentia are preyed on by snakes, birds of prey, and mammalian carnivores. To evade predators, common neacomys are nocturnal, making it harder to be detected.

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

One documented case of common neacomys carrying hantavirus was noted in 2008, but no occurrences have been noted since then. Due to their diet of insects and seeds, common neacomys are likely seed dispersers, similar to other rodents. They also provide pest control by consuming insects. (Bi, et al., 2008; "International Union for Conservation of Nature", 2016)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Aside from their contribution to insect control, no economic importance for common neacomys has been recorded.

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

Common neacomys are a possible reservoir for hantavirus, and thus may pose a threat to human wellness in South America. (Bi, et al., 2008)

  • Negative Impacts
  • injures humans
    • carries human disease

Conservation Status

Common neacomys are considered to have stable populations in South America. Their populations experience large fluctuations throughout the year, but are considered common. According to the IUCN Red List, common neacomys are of least concern. ("International Union for Conservation of Nature", 2016)

Other Comments

Common neacomys are relatively unresearched, and more research is needed to understand them completely.


Gavin Skaar (author), University of Washington, Laura Prugh (editor), University of Washington.



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

World Map


uses sound to communicate


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.


an animal that mainly eats meat


uses smells or other chemicals to communicate


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.


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.


An animal that eats mainly insects or spiders.


having the capacity to move from one place to another.


This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

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


rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.


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


uses touch to communicate


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


uses sight to communicate

year-round breeding

breeding takes place throughout the year


2016. "International Union for Conservation of Nature" (On-line). Neacomys spinosus. Accessed June 02, 2019 at

Bi, Z., P. Formenty, C. Roth. 2008. Hantavirus Infection: a review and global update. Journal of Infection in Developing Countries, 2: 3-23. Accessed June 02, 2019 at

Hice, C., P. Velazco. 2013. Relative Effectiveness of Several Bait and Trap Types for Assessing Terrestrial Small Mammal Communities in Neotropical Rainforest. Museum of Texas Tech University, Occasional Papers, 316: 1-16. Accessed June 02, 2019 at

Hurtado, N., V. Pacheco. 2017. Revision of Neacomys spinosus (Thomas, 1882) (Rodentia: Cricetidae) with emphasis on Peruvian populations and the description of new species. Zootaxa, 4242: 401-440. Accessed June 02, 2019 at

Lawrence, B. 1941. Neacomys from Northwestern South America. Journal of Mammalogy, 22: 418-427. Accessed June 02, 2019 at

Pardiñas, U., J. Patton. 2015. Mammals of South America, Volume 2: Rodents. University of Chicago Press. Accessed June 02, 2019 at