Geographic Range
Bunny rats (
Reithrodon auritus
), also commonly called rata conejo or coney rats, are found in the Patagonian region
of Argentina, southern Chile, and parts of Uruguay.The type locality for
Reithrodon auritus
is on the south bank of the Rio de la plata in the southern pampas of Buenos Aires,
Argentina.
- Biogeographic Regions
- neotropical
Habitat
Reithrodon auritus
is most commonly found in open habitats such as cultivated fields, pampas, stony
hills, and sandy coasts. They inhabit a wide range of elevations, found sea level
to 2170 meters elevation. Bunny rats live in burrows that they dig themselves or they
make use of abandoned burrows made by other fossorial mammals. They also use natural
cavities among rocks.
- Habitat Regions
- temperate
- terrestrial
- Terrestrial Biomes
- savanna or grassland
- chaparral
- scrub forest
- Other Habitat Features
- agricultural
Physical Description
Bunny rats have thick, soft fur. The upper part is a mix of grayish and black hairs
and the underside is whitish or grayish. An adult bunny rat has a total body length
of 195 to 269 mm, tail length of 65 to 104 mm, up to 65% of body length. They have
an average body mass of about 80 g and a resting metabolic rate of 0.4280 W. Some
key physical features used to identify
Reithrodon auritus
are: they have two grooves on the enamel of the upper incisors, there is a reduction
in size of the outer hind toes, the middle hind toes are webbed, and the ears are
large, rounded, and covered with hair.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
Reproduction
The mating system of bunny rats is not well understood. It is thought that males attempt to mate with as many receptive females as they can.
- Mating System
- polygynous
Bunny rats are reproductively active during the spring months.
Reithrodon
species have been found to breed throughout the year and the number of young varies
considerably, from 1 to 8 with an average of 4.53. Females become sexually mature
at about two months old, before reaching a body mass of 52g. Males take a little longer
to reach sexual maturity; when their seminal vesicles are longer than 12mm which is
around three months of age.
- Key Reproductive Features
- iteroparous
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
Females nurse and care for their young until they are weaned. They leave the young
in their grass or fur-lined nests, providing little else in the way of protection.
Males do not invest in the care of their young.
- Parental Investment
- precocial
-
pre-fertilization
- provisioning
-
protecting
- female
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
provisioning
-
pre-independence
- provisioning
Lifespan/Longevity
The average lifespan of
Reithrodon auritus
in the wild is 3.7 months with a maximum longevity in the wild of about 15 months.
One captive bunny rat lived for 5.5 years. Lifespan is limited by predation from
owls.
Behavior
Bunny rats are primarily social mammals, but can also be solitary depending on population
densities. They are both diurnal and nocturnal, depending on the weather conditions.
They construct burrows that go vertically into the turf and are from 4 to 7 cm in
diameter. In their burrows they construct nests made of fine, dry grasses or wool
in areas where they co-occur with sheep.
Home Range
Communication and Perception
Little is known about specific forms of communication in bunny rats. Like other mammals, they are likely to use chemical communication to convey reproductive state.
- Communication Channels
- chemical
Food Habits
Reithrodon auritus
mainly feeds on grasses and other plants with tuberous rhizomes and roots. The stomach
contents of bunny rats in southeastern Buenos Aires province showed that their diet
consisted only of plant material, mostly grasses.
Lolium multiflorum
and
Poa
species made up 74% of stomach content dry weight. The variety of grasses in stomach
contents was less than the variety of grasses available, suggesting that they may
specialize on only a few types of grasses. Bunny rats in captivity eat their own body
mass of green vegetation every night.
- Plant Foods
- leaves
- roots and tubers
Predation
Reithrodon auritus
are main prey items throughout their range for great horned owls (
Bubo virginianus
), common barn owls (
Tyto alba
), other owl species, and buzzard-eagles. It is suggested that Patagonian opossums
(
Lestodelphys halli
) are predators because they have been captured in the same trapline as
Reithrodon auritus
. Humans may eat bunny rats as well. Bunny rats don't seem to respond to noises, even
as close as 2 meters away. Their cryptic coloration and escape to burrows may help
protect them from predation somewhat.
- Anti-predator Adaptations
- cryptic
Ecosystem Roles
Bunny rats are host to many ectoparasites. In Buenos Aires Province they are home
to an endoparasite called
Stilestrongylus aureus
. They are also an important prey source for owls and small mammalian carnivores.
Bunny rats use burrows constructed by other species, including tuco-tucos (
Ctenomys
) and armadillos (
Dasypodidae
). They may inhabit these tunnels along with other rodent species, including long-haired
grass mice (
Akodon longipilis
) and long-tailed pygmy rice rats (
Oligoryzomys longicaudatus
).
- Ecosystem Impact
- disperses seeds
- tuco-tucos ( Ctenomys )
- armadillos ( Dasypodidae )
- long-tailed pygmy rice rats ( Oligoryzomys longicaudatus )
- long-haired grass mice ( Akodon longipilis )
Economic Importance for Humans: Positive
Bunny rats are important members of their native ecosystems.
Economic Importance for Humans: Negative
Bunny rats have become pests in some areas because they consume such large quantities
of grasses. At high population densities they can deteriorate pasture quality for
cattle.
- Negative Impacts
- crop pest
Conservation Status
Reithrodon auritus populations are protected in some national parks and reserves but are not threatened or endangered. They are listed under lower risk and sublisted as a least concern on the IUCN redlist.
Additional Links
Contributors
Tanya Dewey (editor), Animal Diversity Web.
Nicholas Johnson (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.
- 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).
- 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.
- chaparral
-
Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- agricultural
-
living in landscapes dominated by human agriculture.
- 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.
- polygynous
-
having more than one female as a mate at one time
- 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).
- 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.
- young precocial
-
young are relatively well-developed when born
- fossorial
-
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
- diurnal
-
- active during the day, 2. lasting for one day.
- 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
- social
-
associates with others of its species; forms social groups.
- 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
- 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.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
References
Nowak, R. 1999. Coney Rat. Pp. 1409 and 1410 in Walker's Mammals of the World , Vol. 2, 6 Edition. Baltimore, MD: John Hopkins University Press.
Pardinas, U., C. Galliari. 2001. Reithrodon auritus. Mammalian Species, American Society of Mammalogists , No. 664: 1-8.
Scaglia, O., C. Velazquez, M. Cauhepe. 1982. Plant composition of coney rat's (Reithrodon auritus) diet. Acta Theriologica , Vol. 27, no. 13-24: 350-353.
Wilson, D., D. Reeder. 1993. Coney Rat. Pp. 740 in Mammal Species of the World , Vol. 3, 2nd Edition. Washington, D.C.: Smithsonian Institution Presss.