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Akodon subfuscusPuno grass mouse

By Gidget Boe

Geographic Range

Puno grass mice (Akodon subfuscus) are distributed in Southern Peru, Bolivia, and both the eastern and western Andean slopes located in the Southern Hemisphere. In Peru they can be located in the Cusco, Apurimac, Arequipa, Ayacucho, and Puno regions, while in Bolivia they can be found in the La Paz region.

The subspecies A. subfuscus subfuscus is found in the eastern Andean slopes and northern Altiplano, while the subspecies A. subfuscus arequipae is found in the western Andean slopes and western Altiplano. (Myers, et al., 1990; Patton, et al., 2015)

Habitat

Puno grass mice can live in completely treeless grassland areas to forests such as Polylepis woodlands. They are frequently found in bunchgrasses and grass clumps, places that contain large rocks, and stone walls surrounding farmland. This habitat is humid and prone to freezing temperatures at night in higher elevations. The Puno grass mice live at an elevational range of 2000 m to 3500 m, but can found as low as 1900 m and as high as 4500 m. (Carlos, et al., 2021; Dunnum, et al., 2016; Myers, et al., 1990; Patton, et al., 2015)

  • Range elevation
    1900 to 4500 m
    6233.60 to 14763.78 ft
  • Average elevation
    2000-3500 m
    ft

Physical Description

Puno grass mice are classified within a group of closely-related Akodon species, which are described as being small and brown, with faint hair stripes on their back. This species group is often referred to as A. boliviensis, which may cause confusion because A. boliviensis is also the name of a species within this group. For clarity, the species group will be referred as the boliviensis group in this account.

Members of the boliviensis group also have yellow around their eyes, small round ears covered in agouti or black hair, and small white hair located on their chin. These rodents have both plantigrade forefeet and hindfeet, which also may have small white hair tufts. Akodon subfuscus itself compared to other members of the boliviensis group has a lining of darker fur varying from a dusky-olive color to grayish brown, and a slightly fuzzy tail which is about 75-81% of the length of their body, averaging at about 68.2 mm. The average total body length of Puno grass mice fall around 159.6 mm. Body mass of A. subfuscus is not available, but a close relative Akodon azarae has an average body mass of 19 g. Teeth of A. subfuscus wear down quickly and easily, but are fairly large in comparison to other members of the boliviensis group. Their mandibular toothrow length averages at about 3.74 mm, and the third upper molar is noted as being small and oval shaped.

In some populations of A. subfuscus, sexual dimorphism is present, but only slightly. Male rodents on average tend to have 1-2% larger skulls than females, but the difference is only significant in A. subfuscus from Arequipa, Peru. It's noted that skulls of members in the boliviensis group increase in length as they age.

Two subspecies of A. subfuscus are recognized, being A. subfuscus subfuscus and A. subfuscus arequipae. Subspecies A. subfuscus arequipae is noted as being smaller, having a thinner mesopterygoid fossa in the skull, and having a duller fur coloring than A. subfuscus subfuscus. The tail length of A. subfuscus subfuscus is on average 75% of their body length, while the tail length of A. subfuscus arequipae is about 81% of their body length. (Del Valle and Busch, 2003; Jayat, et al., 2010; Myers, et al., 1990; Patton, et al., 2015)

  • Sexual Dimorphism
  • male larger
  • Average length
    159.6 mm
    6.28 in

Reproduction

Information on the mating systems of A. subfuscus is not available, but other Akodon species such as Akodon azarae are mentioned as being polygynous, with males mating with more than one female. Outside of reproductive season, male and female A. azarae mates may occupy the same nest, but during reproductive season will distance themselves or become aggressive. Males will also show aggression against other males when females are present. (Bonatto, et al., 2013; Suárez and Kravetz, 2001)

There is no information on the breeding season of A. subfuscus. There is however a close relative, Akodon boliviensis was found to start reproductive activity during the Southern Hemisphere's late winter months (July and August), with all mice being reproductively active during the spring (September, October, and November). Another close relative, Akodon polopi were most likely to be found pregnant during November and December.

Information on the gestation of A. subfuscus is not available, but a related species A. azarae has a gestation period of 22-23 days. Furthermore, they can produce about 3 litters in their lifetime with an average 4.6 pups per litter. Young A. azarae are weaned 14-15 days old and reach sexual maturity at 60 days old. Interestingly, when females of A. boliviensis were observed, those that were lactating had a slightly redder fur tint than rodents that were not. (Bonatto, et al., 2013; Jayat, et al., 2010)

  • Breeding season
    Late winter (July, August) and spring (September, October, November) for closely related A. boliviensis

There is no data on parental care for A. subfuscus. The parental investment in a closely related Akodon group A. azarae find that only female A. azarae care for young. Female A. azarae will lick and groom and give milk to their pups, and will start weaning them when they are 15 days old. (Bonatto, et al., 2013; Suarez and Busch, 2011)

Lifespan/Longevity

Puno grass mice live about 1-2 years in the wild. There is no information on lifespan in captivity for A. subfuscus, but another member of the Akodon species A. azarae had an average laboratory lifespan of 8-10 months for both males and females, with the highest on record for males being 40 months and females being 28 months. (Dunnum, et al., 2016; Espinosa, 1995)

  • Typical lifespan
    Status: wild
    1 to 2 years

Behavior

There is no specific data on Akodon subfuscus in regards to behavior or activity, but other Akodon species such as A. azarae have been observed to build and occupy nests on the surface and burrows underground. Different Akodon species have times that they are active. While A. azarae can be nocturnal or diurnal, other Akodon species may specialize in being only nocturnal, only diurnal, or crepuscular.

There is no specific data on A. subfuscus in regards to interaction with others of the same species, but the related A. azarae can socially tolerate other mice around them, and may even share nesting sites as long as it is not breeding season. Once breeding season hits, A. azarae become aggressive towards each other. (Hodara, et al., 1997; Patton, et al., 2015; Suárez and Kravetz, 2001)

Home Range

There is no data specifically on A. subfuscus, but males of a related species A. azarae are known to have wider home ranges than females, and may overlap their territory with females while avoiding other male territories. Female A. azarae were found to have home ranges between 36 m^2 and 317.4 m^2, while males had home ranges between 67.2 m^2 and 499 m^2, the largeness depending on how many overlapping female mice were present in the territory. (Bonatto, et al., 2012; Bonatto, et al., 2013)

Communication and Perception

There is no specific information on how Akodon subfuscus communicates, but rodents in general perceive the world with sight, smell, touch, and sound. Often rodents are found to have poor eyesight, but an excellent sense of smell and hearing which they use to communicate chemically and vocally. A related species to Puno grass mice, Akodon azarae can communicate using chemical scents to indicate presence or territory. (Burn, 2008; Patton, et al., 2015; Suárez and Kravetz, 2001)

Food Habits

The diet of Puno grass mice is primarily insectivorous, but their full diet consists of both arthropods (adult and larvae) and various plants. Puno grass mice are seen to have seasonal variation in food choice, with plants becoming more frequently eaten during the dry season (May to September), consuming the seeds and other plant parts containing vascular plant tissue. (Solari, 2007)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems
  • seeds, grains, and nuts

Predation

While there is no data on predation specifically for A. subfuscus, a closely related species A. boliviensis has been listed as being prey for Culpeo Foxes. Other species in Akodon such as Abrothrix longipilis, Abrothrix olivaceus and Akodon azarae are known to face predation by birds of prey such as owls. (Patton, et al., 2015; Pia, et al., 2003; Simonetti, 1989)

Ecosystem Roles

While there is no specific information regarding the roles of A. subfuscus, members of Akodon are prey for different types of predators, and contribute to predation on arthropods and various plants. Furthermore, A. boliviensis is a closely associated species that helps the life cycle of parasitic Trypanosoma cruzi by consuming a carrier bug called Triatoma infestans. (Cortez, et al., 2006)

Economic Importance for Humans: Positive

Akodon subfuscus and other Akodon species have no data indicating a positive economic importance.

Economic Importance for Humans: Negative

There is no data indicating Akodon subfuscus has a negative economic importance for this species, however a closely related species A. boliviensis is a known transmitter of Trypanosoma cruzi. The parasite T. cruzi causes Chagas disease in humans, which can result in death. Another closely related species, A. azarae is considered one of many pest rodents in farmlands. (Cortez, et al., 2006; Miño, et al., 2007)

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

Conservation Status

The Puno grass mouse is listed by the IUCN as Least Concern, and its range inhabits several areas that are under protection. Currently it is facing no threats, and is considered a stable population due to its wide distribution. (Dunnum, et al., 2016)

Other Comments

Akodon subfuscus is classified within a group of closely related species often referred to as A. boliviensis, otherwise called the boliviensis group. This group consists of the species A. boliviensis as well as the other Akodon species A. subfuscus, A. lutescens, A. spegazzinii, A. kofordi, A. polopi, A. fumeus and A. juninensis. (Jayat, et al., 2010; Patton, et al., 2015)

Contributors

Gidget Boe (author), University of Washington, Laura Prugh (editor), University of Washington, Tanya Dewey (editor), University of Michigan-Ann Arbor.

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

agricultural

living in landscapes dominated by human agriculture.

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.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

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

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

forest

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

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

insectivore

An animal that eats mainly insects or spiders.

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.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

polygynous

having more than one female as a mate at one time

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

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

social

associates with others of its species; forms social groups.

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 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.

References

Bonatto, F., J. Coda, D. Gomez, J. Priotto, A. Steinmann. 2013. Inter-male aggression with regard to polygynous mating system in Pampean grassland mouse, Akodon azarae (Cricetidae: Sigmodontinae). Journal of Ethology, 31: 223–231. Accessed June 01, 2021 at https://link.springer.com/article/10.1007/s10164-013-0370-4.

Bonatto, F., M. Gomez, J. Priotto, A. Steinmann. 2012. Mating strategies of Pampean mouse males. Animal Biology, 62: 381-396. Accessed September 21, 2021 at https://www.researchgate.net/publication/274532725_Mating_strategies_of_Pampean_mouse_males.

Burn, C. 2008. What is it like to be a rat? Rat sensory perception and its implications for experimental design and rat welfare. Applied Animal Behaviour Science, 112: 1-32. Accessed June 06, 2021 at https://www.researchgate.net/publication/242113938_What_is_it_like_to_be_a_rat_Rat_sensory_perception_and_its_implications_for_experimental_design_and_rat_welfare.

Carlos, J., R. Salcedo, C. Locklin. 2021. "Western South America: Peru and Bolivia" (On-line). Accessed June 01, 2021 at https://www.worldwildlife.org/ecoregions/nt1003.

Cortez, M., A. Pinho, P. Cuervo, F. Alfaro, M. Solano, S. Xavier, P. D'Andrea, O. Fernandes, F. Torrico, F. Noireau, A. Jansen. 2006. Trypanosoma cruzi (Kinetoplastida Trypanosomatidae): ecology of the transmission cycle in the wild environment of the Andean valley of Cochabamba, Bolivia. Experimental parasitology, 114: 305-313. Accessed June 01, 2021 at https://pubmed.ncbi.nlm.nih.gov/16797540/.

Del Valle, J., C. Busch. 2003. Body composition and gut length ofAkodon azarae (Muridae: Sigmodontinae): relationship with energetic requirements. Acta Theriol, 48: 347–357. Accessed August 16, 2021 at https://link.springer.com/article/10.1007/BF03194174.

Dunnum, J., J. Vargas, N. Bernal, H. Zeballos, E. Vivar, B. Patterson. 2016. "Akodon subfuscus" (On-line). The IUCN Red List of Threatened Species 2016. Accessed May 11, 2021 at https://www.iucnredlist.org/species/760/22381005.

Espinosa, M. 1995. Akodon azarae (Rodentia-Cricetidae): Breeding, Management and Reproductive Performance in Laboratory Conditions.. Revista Brasileira de Biologia, 55: 201-206. Accessed June 05, 2021 at https://www.researchgate.net/publication/270277654_Akodon_azarae_Rodentia-Cricetidae_Breeding_Management_and_Reproductive_Performance_in_Laboratory_Conditions.

Hodara, K., O. Suarez, F. Kravetz. 1997. Nesting and digging behavior in two rodent species (Akodon azarae and Calomys laucha) under laboratory and field conditions. Zeitschrift fur Saugetierkunde, 62: 23-29. Accessed June 06, 2021 at https://www.researchgate.net/publication/289178609_Nesting_and_digging_behavior_in_two_rodent_species_Akodon_azarae_and_Calomys_laucha_under_laboratory_and_field_conditions.

Jayat, P., P. Ortiz, J. Salazar-Bravo, U. Pardiñas, G. D'Elía. 2010. The Akodon boliviensis species group (Rodentia: Cricetidae: Sigmodontinae) in Argentina: species limits and distribution, with the description of a new entity. Zootaxa, 2409: 1-61. Accessed June 01, 2021 at https://www.researchgate.net/publication/236918557_The_Akodon_boliviensis_species_group_Rodentia_Cricetidae_Sigmodontinae_in_Argentina_species_limits_and_distribution_with_the_description_of_a_new_entity.

Mena Alvarez, J., L. Aguirre, J. Carrera-E, H. Gomez, S. Solari. 2011. Small mammal diversity in the tropical Andes: an overview. Climate Change and Biodiversity in the Tropical Andes, 1: 260-275. Accessed June 01, 2021 at https://www.researchgate.net/publication/257925729_Small_mammal_diversity_in_the_tropical_Andes_an_overview.

Miño, M., R. Cavia, I. Villafañe, D. Bilenca, M. Busch. 2007. Seasonal abundance and distribution among habitats of small rodents on poultry farms. A contribution for their control. International Journal of Pest Management, 53: 311-316. Accessed June 06, 2021 at https://www.researchgate.net/publication/215624795_Seasonal_abundance_and_distribution_among_habitats_of_small_rodents_on_poultry_farms_A_contribution_for_their_control.

Myers, P., J. Patton, M. Smith. 1990. A review of the Boliviensis group of Akodon (Muridae: Sigmodontinae): with emphasis on Peru and Bolivia. Miscellaneous Publications, Museum of Zoology, University of Michigan, 177: 1-92. Accessed May 31, 2021 at https://www.researchgate.net/publication/30857152_A_review_of_the_Boliviensis_group_of_Akodon_Muridae_Sigmodontinae_with_emphasis_on_Peru_and_Bolivia.

Patton, J., U. Pardiñas, G. D'Elía. 2015. Mammals of South America, Volume 2: Rodents. London: University of Chicago Press. Accessed June 01, 2021 at https://www.researchgate.net/publication/304515084_MAMMALS_OF_SOUTH_AMERICA_VOL_2_RODENTS.

Pia, M., M. López, A. Novaro. 2003. Effects of livestock on the feeding ecology of endemic culpeo foxes (Pseudalopex culpaeus smithersi) in central Argentina. Revista Chilena de Historia Natural, 76: 313-321. Accessed June 01, 2021 at https://www.researchgate.net/publication/254399881_Effects_of_livestock_on_the_feeding_ecology_of_endemic_culpeo_foxes_Pseudalopex_culpaeus_smithersi_in_central_Argentina.

Simonetti, J. 1989. Microhabitat Use by Small Mammals in Central Chile. Oikos, 56: 309–318. Accessed May 13, 2021 at https://www.jstor.org/stable/3565615?seq=1.

Solari, S. 2007. Trophic relationships in a highland rodent assemblage of Manu National Park, Cusco, Peru. The Quintessential Naturalist: honoring the Life and Legacy of Oliver P. Pearson, 134: 225-240. Accessed June 05, 2021 at https://www.researchgate.net/publication/230708911_Trophic_relationships_in_a_highland_rodent_assemblage_of_Manu_National_Park_Cusco_Peru.

Suarez, O., M. Busch. 2011. Reproductive strategies in Akodon azarae (Rodentia, Muridae). Canadian Journal of Zoology, 82: 1572-1577. Accessed June 06, 2021 at https://www.researchgate.net/publication/237973574_Reproductive_strategies_in_Akodon_azarae_Rodentia_Muridae.

Suárez, O., F. Kravetz. 2001. Male-female interaction during breeding and non-breeding seasons in Akodon azarae (Rodentia, Muridae). Iheringia. Série Zoologia, 91: 171-176. Accessed June 01, 2021 at https://www.scielo.br/j/isz/a/BNX8gGR86F6LqXrFtymdV7K/?lang=en.

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