Animal Diversity Web

Ge­o­graphic Range

Mon­tane co­l­ilar­gos (Mi­cro­ry­zomys min­u­tus) live in South Amer­ica, rang­ing from cen­tral Bo­livia to north­ern Venezuela. Specif­i­cally, they have been found as far south as Co­marapa, Bo­livia, at 17°51'S/64°42'W, and as far north as Caripe, Venezuela, at 10º012'N/63º32'W. There have been no changes to this range in re­cent years. (Car­leton and Musser, 1989)

• Biogeographic Regions
• neotropical
  • native

Habi­tat

Mon­tane co­l­ilar­gos are ter­res­trial ro­dents that have been recorded at el­e­va­tions from 800 to 4,255 m, but are most com­monly found be­tween 2,000 to 3,500 me­ters. They pre­fer lower and upper mon­tane rain­forests, com­monly re­ferred to as cloud forests. Mon­tane co­l­ilar­gos live in ar­bores­cent habi­tats, mean­ing areas with lots of trees. They pre­fer wet habi­tats with dense fog and rain. They re­quire a habi­tat with many places in which to seek shel­ter, such as holes, rocks, roots, and strat­i­fied un­der­story. (Car­leton and Musser, 1989)

• Habitat Regions
• temperate
• tropical
• terrestrial

• Terrestrial Biomes
• forest
• mountains

• Range elevation

  800 to 4,255 m

  2624.67 to ft

• Average elevation

  2,000 - 3,500 m

  ft

Phys­i­cal De­scrip­tion

The pelage of mon­tane co­l­ilar­gos is an ochra­ceous-tawny color. There is usu­ally lit­tle to no con­trast in color be­tween their ven­tral body fur and their dor­sal fur. Their tails are dark brown, and the dor­sal sur­faces of their front and hind feet are also brown in color. Mon­tane co­l­ilar­gos have coats that also fea­ture an or­ange-buff spot of fur be­hind their pin­nae. Pop­u­la­tions found in Ecuador are usu­ally darker in color, with no con­trast be­tween upper and lower parts. In Bo­livia, Peru, Co­lum­bia, and Venezuela, in­di­vid­u­als are lighter and have a more no­table con­trast be­tween their dor­sal and ven­tral sides.

The hind feet of mon­tane co­l­ilar­gos are wide, and their plan­tar pads are large and soft. There is lit­tle sex­ual di­mor­phism be­tween males and fe­males, but males weigh more on av­er­age than fe­males. Recorded body lengths of mon­tane co­l­ilar­gos vary from 79 to 97 mm. Their hind feet are 24 to 26 mm long, and their ears are 15 to 16 mm long. Weights range from 9.5 to 26 g.

One dis­tinc­tive fea­ture of mon­tane co­l­ilar­gos is that their tails are more than 145% the length of their heads and bod­ies com­bined - con­sis­tently longer than 110 mm. Tail lengths range from 115 to 142 mm. It was not spec­i­fied whether these mea­sure­ments in­cluded young in­di­vid­u­als or only adults. Mon­tane co­l­ilar­gos can be dis­tin­guished from their clos­est rel­a­tives, Páramo co­l­ilar­gos (Mi­cro­ry­zomys al­tissimus), by their longer tails and darker, less con­trasted pelage. (Ca­bello, et al., 2014; Car­leton and Musser, 1989; Lee, 2008)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger

• Range mass

  9.5 to 26 g

  0.33 to 0.92 oz

• Range length

  79 to 97 mm

  3.11 to 3.82 in

Re­pro­duc­tion

Lit­tle in­for­ma­tion is avail­able re­gard­ing the re­pro­duc­tive habits of mon­tane co­l­ilar­gos. Stud­ies on other species in the fam­ily Criceti­dae have shown a vast range in the size of male testes com­pared to over­all body size. This mea­sure­ment is usu­ally a good in­di­ca­tor of the type of breed­ing sys­tem (e.g. monog­a­mous, polyg­y­nous), but since it varies so much within the fam­ily and there is no data on this par­tic­u­lar species, no in­for­ma­tion can be gleaned from this. An­other species in the same fam­ily that is also na­tive to South Amer­ica, Azara's grass mice (Akodon azarae), has a polyg­y­nous breed­ing sys­tem that can be char­ac­ter­ized as fe­male de­fense polyg­yny. How­ever, it is un­clear if mat­ing sys­tems of cer­tain species of ro­dents can be gen­er­al­ized to all ro­dents in that fam­ily. (Bon­atto, et al., 2013; Ca­bello, et al., 2014; Ke­nagy and Trom­bu­lak, 1986)

It is be­lieved that mon­tane co­l­ilar­gos breed at the be­gin­ning of the rainy sea­son, and lit­ter size is typ­i­cally 3 to 4 in­di­vid­u­als. It has also been hy­poth­e­sized that mon­tane co­l­ilar­gos dif­fer from other ro­dents in that they may start their re­pro­duc­tion when en­ergy and nu­tri­ent lev­els are suf­fi­cient, in­stead of dur­ing a cer­tain sea­son. This is cur­rently the only in­for­ma­tion avail­able about the re­pro­duc­tive be­hav­ior of mon­tane co­l­ilar­gos, how­ever there is more in­for­ma­tion on Azara's grass mice (Akodon azarae), a closely re­lated species in the fam­ily Criced­i­tae. The ges­ta­tion pe­riod of Azara's grass mice is 22.7 days, and at 14 to 15 days the young are weaned. Young reach sex­ual ma­tu­rity at 60 days. How­ever, while Azara's grass mice are in the same fam­ily as mon­tane co­l­ilar­gos, it is un­clear whether gen­er­al­iza­tions like these can be made across species. (Bon­atto, et al., 2013; Ca­bello, et al., 2014)

• Key Reproductive Features
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous

• Breeding season

  January - March

• Range number of offspring

  3 to 4

There is lit­tle in­for­ma­tion avail­able about the parental in­vest­ment of mon­tane co­l­ilar­gos. How­ever, there is some in­for­ma­tion avail­able on an­other ro­dent in the Criceti­dae fam­ily. Grey dwarf ham­sters (Crice­tu­lus mi­gra­to­rius) are a cricetid that has been ob­served dis­play­ing ma­ter­nal care in­clud­ing nurs­ing, brood­ing, groom­ing, build­ing nests, and caching food. It is un­clear if these types of be­hav­iors can be gen­er­al­ized to other mem­bers of the same fam­ily, though. (Gro­mov, et al., 2006)

Lifes­pan/Longevity

There is cur­rently no pub­lished data on the longevity of mon­tane co­l­ilar­gos, how­ever there is some in­for­ma­tion about a sim­i­lar species within the same fam­ily. Azara's grass mice (Akodon azarae) are mice also in the fam­ily Criceti­dae. They have a lifes­pan of ap­prox­i­mately one year. Be­cause they are only in the same fam­ily as mon­tane co­l­ilar­gos, it is not cer­tain that the longevity of Azara's grass mice car­ries over be­tween species. (Bon­atto, et al., 2013)

Be­hav­ior

There is lit­tle in­for­ma­tion avail­able about the be­hav­ior of mon­tane co­l­ilar­gos, but some in­for­ma­tion was found on an­other type of rice rat from the same fam­ily. Marsh rice rats (Ory­zomys palus­tris nata­tor) are in the fam­ily Criceti­dae, and are soli­tary, noc­tur­nal, and avid nest builders. It is un­clear, how­ever, if these char­ac­ter­is­tics can be gen­er­al­ized to other species such as mon­tane co­l­ilar­gos. (Worth, 1950)

• Key Behaviors
• terricolous
• motile

Home Range

Lit­tle is known about the home range of mon­tane co­l­ilar­gos.

Com­mu­ni­ca­tion and Per­cep­tion

Once again, there is lit­tle in­for­ma­tion avail­able about the com­mu­ni­ca­tion of mon­tane co­l­ilar­gos. How­ever, some in­for­ma­tion may be gleaned from marsh rice rats (Ory­zomys palus­tris nata­tor), an­other mem­ber of the fam­ily Criceti­dae. When ex­posed to mem­bers of the same species, marsh rice rats re­spond first by seek­ing shel­ter, and then emit­ting high-pitched squeaks to make their an­i­mos­ity clear. How­ever, as pre­vi­ously men­tioned, it is un­clear if char­ac­ter­is­tics of marsh rice rats can be gen­er­al­ized to other mem­bers of the fam­ily such as mon­tane co­l­ilar­gos. (Worth, 1950)

• Perception Channels
• tactile
• chemical

Food Habits

Mon­tane co­l­ilar­gos are om­niv­o­rous. Based on fecal sam­ples, they have been doc­u­mented to eat a wide va­ri­ety of food items, in­clud­ing arthro­pods, fruits, plant re­mains, and my­c­or­rhizal spores. They seem to show a pref­er­ence for arthro­pods above all else. Some known spe­cific food items of mon­tane co­l­ilar­gos in­clude bee­tles (order Coleoptera), and seeds from the genus Gaulthe­ria. They are also known to con­sume palm seeds. (Ca­bello, et al., 2014; Sahley, et al., 2015)

• Primary Diet
• carnivore
  • insectivore
  • eats non-insect arthropods
• herbivore
  • folivore
  • frugivore
  • granivore
• omnivore

• Animal Foods
• insects
• terrestrial non-insect arthropods

• Plant Foods
• leaves
• seeds, grains, and nuts
• fruit

• Other Foods
• fungus

Pre­da­tion

Cur­rently, there is not much in­for­ma­tion on pre­da­tion of mon­tane co­l­ilar­gos. How­ever, in­for­ma­tion pub­lished about other mem­bers of the fam­ily Criced­i­tae sug­gests that mon­tane co­l­ilar­gos are likely preyed upon by small to medium-sized car­ni­vores and birds of prey that also re­side in cloud forests. Based on in­for­ma­tion on other cricetids, mon­tane co­l­ilar­gos may avoid preda­tors by tak­ing ad­van­tage of the cover pro­vided by its habi­tat, which in­cludes holes, rocks, and veg­e­ta­tion (King, 1985)

Ecosys­tem Roles

Mon­tane co­l­ilar­gos pro­vide a food source for preda­tors, and con­trol the pop­u­la­tions of arthro­pods that they eat. They also dis­perse seeds and my­c­or­rhizal spores. This species is a host to the par­a­site Leish­ma­nia brazilien­sis. (Ca­bello, et al., 2014; Sahley, et al., 2015)

• Ecosystem Impact
• disperses seeds

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

There are no known pos­i­tive ef­fects of mon­tane co­l­ilar­gos on hu­mans.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Mi­cro­ry­zomys min­u­tus are known to carry a species of leish­ma­ni­a­sis (Leish­ma­nia brazilien­sis), a par­a­site which can be trans­ferred to hu­mans. There­fore, mon­tane co­l­ilar­gos can have neg­a­tive im­pacts on human health. Cof­fee-grow­ing com­mu­ni­ties are par­tic­u­larly vul­ner­a­ble to leish­ma­ni­a­sis, be­cause these plan­ta­tions house large pop­u­la­tions of small mam­mals, in­clud­ing mon­tane co­l­ilar­gos.

Since the habi­tat of mon­tane co­l­ilar­gos in­cludes an­thro­pogeni­cally dis­turbed areas such as crop­lands, they may also be con­sid­ered a crop pest. (Alexan­der, et al., 1998; Ca­bello, et al., 2014)

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

Con­ser­va­tion Sta­tus

Mon­tane co­l­ilar­gos are clas­si­fied as an an­i­mal of least con­cern by the IUCN red list. Cur­rent pop­u­la­tion sizes un­known, but pop­u­la­tions are not se­verely frag­mented, and this an­i­mal is found in mul­ti­ple pro­tected areas. The pri­mary threat to this species is habi­tat loss, in­clud­ing de­for­esta­tion by log­ging and other forms of wood har­vest­ing. (Cas­sola, 2019)

• IUCN Red List

  Least Concern

Con­trib­u­tors

Eleanore Sam­meth (au­thor), Uni­ver­sity of Wash­ing­ton, Laura Prugh (ed­i­tor), Uni­ver­sity of Wash­ing­ton, Galen Bur­rell (ed­i­tor), Spe­cial Pro­jects.

Ref­er­ences

Alexan­der, B., C. Lozano, D. Barker, S. Mc­Cann, G. Adler. 1998. De­tec­tion of Leish­ma­nia (Vian­nia) Brazilien­sis Com­plex in Wild Mam­mals from Colom­bian Cof­fee Plan­ta­tions by PCR and DNA Hy­bridiza­tion. Acta Trop­ica, 69: 41-50.

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). Stud­ies on Neotrop­i­cal Fauna and En­vi­ron­ment, 31: 223-231.

Ca­bello, D., G. Bianchi-Perez, P. Ra­moni-Per­azzi. 2014. Pop­u­la­tion Dy­nam­ics of the Rat Mi­cro­ry­zomys Min­u­tus (Ro­den­tia: Muri­dae) in the Venezue­lan Andes. Re­vista de Bi­olo­gia Trop­i­cal, 54: 651-655.

Car­leton, M., G. Musser. 1989. SYS­TEM­ATIC STUD­IES OF ORY­ZOMYINE RO­DENTS (MURI­DAE, SIG­MOD­ON­TI­NAE): A SYN­OP­SIS OF MI­CRO­RY­ZOMYS. Bul­letin of the Amer­i­can Mu­seum of Nat­ural His­tory, 191: 1-81.

Cas­sola, F. 2019. "IUCN Red List of Threat­ened Species" (On-line). Ac­cessed May 14, 2019 at http://​dx.​doi.​org/​10.​2305/​IUCN.​UK.​2016-3.​RLTS.​T13408A22343700.​en.

Gro­mov, V., A. Surov, G. Ryurikov. 2006. Ma­ter­nal care in cap­tive gray ham­ster Crice­tu­lus mi­gra­to­rius (Ro­den­tia, Criceti­dae). Russ­ian Jour­nal of The­ri­ol­ogy, 5: 73-77.

Ke­nagy, G., S. Trom­bu­lak. 1986. Size and Func­tion of Mam­malian Testes in Re­la­tion to Body Size. Jour­nal of Mam­mal­ogy, 67: 1-22.

King, C. 1985. In­ter­ac­tions be­tween Wood­land Ro­dents and Their Preda­tors. The Zo­o­log­i­cal So­ci­ety of Lon­don, 55: 219-247.

Lee, T. 2008. The Mam­mals of the Tem­per­ate Forests of Volcán Sumaco, Ecuador. Oc­ca­sional Pa­pers, 276: 2-10.

Sahley, K., K. Cer­vantes, V. Pacheco, E. Salas, D. Pare­des. 2015. Diet of a Sig­mod­on­tine Ro­dent As­sem­blage in a Pe­ru­vian Mon­tane For­est. Jour­nal of Mam­mal­ogy, 96: 1071-1080.

Worth, C. 1950. Ob­ser­va­tions on the Be­hav­ior and Breed­ing of Cap­tive Rice Rats and Woodrats. Jour­nal of Mam­mal­ogy, 31: 421-426.