Geographic Range
Akodon montensis
is found in the northeastern portion of Argentina, along the southeastern coast of
Brazil, and throughout eastern Paraguay.
- Biogeographic Regions
- neotropical
Habitat
Akodon montensis
is found in both temperate and tropical habitats. Within these habitats it occupies
evergreen, semi-deciduous, and riparian gallery forests. It is also found in grassland
and coastal biomes and in open areas. Furthermore, it occurs in agricultural fields,
gardens, and young secondary growth. Generally, the species prefers areas with ground
cover and leaf litter.
Akodon montensis
can be found at elevations of 800 m, but is more common at elevations of 900 m or
higher.
- Habitat Regions
- temperate
- tropical
- terrestrial
- Terrestrial Biomes
- savanna or grassland
- forest
- Aquatic Biomes
- coastal
- Other Habitat Features
- agricultural
- riparian
Physical Description
Akodon montensis
is a small rodent with a heavy body that is often described as closely resembling
a vole. Young differ from adults only in size, and males (45 g) are slightly larger
than females (40 g). Adult mass ranges from 19 to 57 g, with a mean of 42 g. Total
length of
Akodon montensis
ranges from 90 to 136 mm, with hind feet ranging from 17 to 28 mm long, ears ranging
from 11 to 21 mm long, and tails ranging from 32 to 98 mm long. Although its basal
metabolic rate is unknown, the basal metabolic rate for other members of
Akodon
is typically around 46 mL of oxygen per hour. Dorsal pelage of
A. montensis
is auburn and fades to lighter tan on the sides. The venter is either reddish grey
or reddish tan with a slight orange hew. It has tan feet and a sparsely haired tail.
Akodon montensis
looks similar to
Akodon cursor
, however,
A. montensis
is smaller than
A. cursor
.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
Reproduction
Reproductive behavior of Akodon montensis has not been extensively studied, and the mating system that best characterizes this species is currently unknown.
Reproductive efforts of male
Akodon montensis
occurs via a four-stage process. First, recrudescence of spermatogenesis occurs,
followed by the act of mating. These two stages take place between October and February
(the wet season). The third stage, regression of activity and spermatogenesis, and
the fourth stage, rest, take place from March to July (the dry season). If the immediate
environment and weather are favorable, mating can take place year round. Typically,
females have two litters but may have more if environmental conditions are favorable.
Litter size ranges from 3 to 10 offspring, with an average litter size of 5. On average,
gestation lasts 23 days, and offspring are typically weaned within 15 days. Males
achieve sexual maturity in 32 to 37 days while females achieve sexual maturity between
35 and 91 days. Sexual maturity is most often reached between October and March. No
information on birth mass is available, but average birth mass of other members of
Akodon
(e.g.,
Akodon lindberghi
and
Akodon azarae
) ranges from 1.97 g to 3.10 g. No information is available concerning time to independence.
Reproductively active and fertile females can be found in the wild with XY chromosomes.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
Information on parental investment specific to
Akodon montensis
is not available. However, in most mammals care of the young (e.g., provisioning
and protecting) is performed by the mother from the time of fertilization until independence.
- Parental Investment
- altricial
- female parental care
-
pre-fertilization
- provisioning
-
protecting
- female
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
provisioning
Lifespan/Longevity
No specific information is available pertaining to the lifespan of
Akodon montensis
, aside from observations that they have a short life expectancy and quick population
turnover . One member of
Akodon
,
Akodon azarae
, has a maximum lifespan of 18 months but typically lives one year or less.
Behavior
Akodon montensis
is solitary, with most intraspecific interactions occurring during mating season.
It is nocturnal and spends much of its time in leaf litter, where it creates tunnels
to travel through and nest in.
Home Range
The home range of
Akodon montensis
is relatively small, with individuals occupying 36 m^2 on average. Home ranges never
exceed 100 m^2 and do not vary in size between genders or seasons.
Communication and Perception
There is no information available on intraspecific communication in
Akodon montensis
. Its close relative,
Akodon cursor
uses olfactory cues to inform conspecifics about reproductive availability and territorial
boundaries.
- Communication Channels
- chemical
Food Habits
Akodon montensis
is omnivorous. Its diet consists of
fungi
, plant matter, and invertebrates (e.g.,
insects
and
spiders
) and does not vary in relation to season. Studies indicate that
A. montensis
prefers foraging on the seeds and mesocarp of
Leandra panifilamentosa
,
Myrceugenia cucullata
,
Rubus sellowii
and
Berberis laurina
. Similar to other small mammals,
A. montensis
caches food.
- Primary Diet
- omnivore
- Animal Foods
- insects
- terrestrial non-insect arthropods
- terrestrial worms
- Plant Foods
- leaves
- roots and tubers
- seeds, grains, and nuts
- fruit
- Other Foods
- fungus
- Foraging Behavior
- stores or caches food
Predation
Aside from
barn owls
, little information is available on the major predators of
Akodon montensis
. Although not documented, it is likely that mammalian
carnivores
,
snakes
, and large
birds
also prey on
Akodon montensis
. The brownish pelage of
Akodon montensis
helps it blend in with leaf litter and avoid predators.
- Anti-predator Adaptations
- cryptic
Ecosystem Roles
Akodon montensis
preys on a variety of small
insects
including
beetles
,
moths
,
flies
, and other
arthropods
. Although limited information is available concerning is major predators, it is likely
an important prey item for many large
birds
and
carnivores
. In addition, it is a host to numerous species of parasitic
protists
in the genus
Besnoitia
and a variety of
nematodes
. It is also a known carrier of
hantavirus
. Finally,
Akodon montensis
may play an important role in the seed dispersal of certain plant species as it is
known to cache seeds throughout its home range.
- Ecosystem Impact
- disperses seeds
- nematodes, ( Nematoda )
- hantaviruses, ( Bunyaviridae )
- parasitic protists ( Besnoitia )
Economic Importance for Humans: Positive
There are no known positive effects of Akodon montensis on humans. However, it may help control insect pest populations throughout its native range.
Economic Importance for Humans: Negative
Akodon montensis
poses two main problems for humans. First, it is a known vector for
hantaviruses
. When transmitted to humans this virus can cause hantavirus pulmonary syndrome which
can be fatal. Secondly, some members of the genus
Akodon
have a significant impact on agriculture by foraging on crops (e.g., rice, maize,
peanuts, and cereal crops), resulting in a 10% to 90% decrease in crop yield.
- Negative Impacts
-
injures humans
- carries human disease
- crop pest
Conservation Status
Although
Akodon montensis
is thought to be decreasing in abundance, it is currently listed as a species of
least concern by the IUCN Red List of Threatened Species.
Other Comments
Akodon montensis
was formerly considered a subspecies of
Akodon cursor
. It has recently been promoted to species level based on several factors, including
occupying a different elevational habitat then
Akodon cursor
and having a different karyotype (2n=24 for
Akodon montensis
, 2n=14/15 for
Akodon cursor
).
Akodon montensis
does not have a gall bladder but
Akodon cursor
does. Due to this recent change in classification, it is often difficult to determine
if the study results apply to
Akodon cursor
or
Akodon montensis
.
Additional Links
Contributors
Meagan Crofoot (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, John Berini (editor), Animal Diversity Web Staff.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- 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.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- agricultural
-
living in landscapes dominated by human agriculture.
- riparian
-
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
- 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.
- 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.
- 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).
- seasonal breeding
-
breeding is confined to a particular season
- year-round breeding
-
breeding takes place throughout the year
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- altricial
-
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.
- female parental care
-
parental care is carried out by females
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- solitary
-
lives alone
- chemical
-
uses smells or other chemicals to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- stores or caches food
-
places a food item in a special place to be eaten later. Also called "hoarding"
- cryptic
-
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.
- omnivore
-
an animal that mainly eats all kinds of things, including plants and animals
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