Blarinomys brevicepsBrazilian shrew mouse

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Geographic Range

Blarinomys breviceps is rarely seen in the wild. As a result, during the 18th and 19th century it was widely assumed that they had become extinct. However, in 2003 and 2005, numerous specimens were captured near Rio De Janeiro, Brazil. Blarinomys breviceps is fossorial and occurs primarily in humid tropical and subtropical forests. Its geographic range includes forested areas in the Atlantic Forest, along the southeastern coast of Brazil, from Bahia State southwards to Misiones, Argentina. Although most sightings have been recorded in mountainous habitats, B. breviceps has also been found at sea level. (Abravaya and Matson, 1975; Abravaya and Matson, 1977; Geise et al., 2008; Silva et al., 2003)

Habitat

Blarinomys breviceps can be found in semideciduous seasonal forests, evergreen forests, and mixed evergreen forests throughout the Atlantic Forest in southeastern Brazil (Geise et al., 2008). It is generally found at elevations between 750 and 1570 m (average 890 m), but has been sighted at sea level as well. (Abravaya and Matson, 1975; Abravaya and Matson, 1977; Davis, 1944; Eisenberg et al., et al., 2008; Geise et al., 2008; Silva et al., 2003)

  • Range elevation
    750 to 1570 m
    2460.63 to 5150.92 ft
  • Average elevation
    890 m
    2919.95 ft

Physical Description

Brazilian shrew-mice have fusiform body morphology, suggesting a fossorial lifestyle. Their pelage is short and velvety, and has a slate-gray base color that becomes reddish-brown along the dorsal surface. They have reduced eyes, which are hidden beneath its fur (Geise et al. 2008; Abravaya and Matson 1977). Their hairless tail is short and usually less than 50% of total head and body length (Abravaya and Matson 1975). They have a conical skull with a flattened brain case and zygomatic breadth exceeds brain case breadth. They have high crowned teeth; however, tooth cusps often become worn flat. They have relatively long claws, which are most pronounced on the pollex. Brazilian shrew-mice exhibit minimal sexual dimorphism, as females have slightly longer tails. (Abravaya and Matson, 1977; Davis, 1944; E and Wilson, 1993; Geise et al., 2008; Silva et al., 2003)

  • Sexual Dimorphism
  • female larger
  • Average mass
    12 g
    0.42 oz
  • Range length
    129 to 161 mm
    5.08 to 6.34 in
  • Average length
    147 mm
    5.79 in

Reproduction

The mating system of Brazilian shrew mice has not been documented.

Although limited information exists for reproductive behavior in Brazilian shrew mice, scrotal males and lactating females have been found in January and February. In addition, pregnant females have been found from September to February (Davis, 1944; Matson, 1977). Based on this information, breeding season is thought to occur two times a year, from January to September, (Abravaya and Matson, 1977; Davis, 1944)

  • Breeding interval
    twice a year
  • Breeding season
    January to September
  • Range number of offspring
    1 to 2
  • Average number of offspring
    1

Parental investment in Blarinomys breviceps has not been documented.

Lifespan/Longevity

Information regarding the lifespan of wild Brazilian shrew mice has not been documented. Captive specimens often refuse food and die within a few days. In general, Sigmondontine rodents live 5 to 12 months in the wild and up to 5 years in captivity. (Abravaya and Matson, 1975; Abravaya and Matson, 1977; E and Wilson, 1993; Geise et al., 2008; Silva et al., 2003)

  • Range lifespan
    Status: captivity
    2 to 72 hours

Behavior

Blarinomys breviceps is fossorial and is thought to live a solitary lifestyle. It is often found during the day, in the upper soil horizon, under a carpet of dead leaves and twigs in secondary forests (Davis, 1944). (Abravaya and Matson, 1975; Abravaya and Matson, 1977; Geise et al., 2008)

Home Range

Home-range size has not been documented for Blarinomys breviceps. However, it resides at the base of densely rooted trees in the leaf litter of gallery forests and often creates burrows along root structures. It appears to be most active during rainy season (Davis, 1944; Abravaya and Matson, 1977; Geise et al., 2008). (Abravaya and Matson, 1975; Abravaya and Matson, 1977; Davis, 1944; Geise et al., 2008)

Communication and Perception

Due to their fossorial lifestyle and solitary nature, Blarinomys breviceps sightings are rare. As a result, little is known of how they communicate with conspecifics and how they perceive their environment. It has reduced eyes, suggesting decreased reliance on sight. Thus, B. breviceps' haptic capabilities may be relatively advanced. (Abravaya and Matson, 1975; Abravaya and Matson, 1977; Davis, 1944; E and Wilson, 1993; Geise et al., 2008; Scheibler and Christoff, 2007)

Food Habits

Although limited information exists on the diet of wild Blarinomys breviceps, evidence suggests it is likely insectivorous (Abravaya and Matson, 1975; Abravaya and Matson, 1977). In captivity, B. breviceps consumes a variety of insects, including orthopterans (e.g., grasshoppers and crickets), lepidopterans (e.g., moths and butterflies), and cockroaches (Blattidae). With the exception of oranges, captive individuals tend to refuse fruits and seeds (Geise et al., 2008). (Abravaya and Matson, 1975; Abravaya and Matson, 1977; Geise et al., 2008)

  • Animal Foods
  • insects
  • Plant Foods
  • fruit

Predation

Blarinomys breviceps' fossorial lifestyle may help it avoid potential predators. However, a study performing dietary analysis on avian predators from South America suggests that B. breviceps has at least 3 main predators: burrowing owls (Athene cunicularia), white-tailed hawks (Buteo albicaudatus), and white-tailed kites (Elanus leucurus). Athene cunicularia is a nocturnal predator, while both B. albicaudatus and E. leucurus are diurnal predators. All three predator species tend to hunt in open environments such as fields and savannas. (Abravaya and Matson, 1977; Davis, 1944; Eisenberg et al., et al., 2008; Geise et al., 2008; Scheibler and Christoff, 2007; Silva et al., 2003)

Ecosystem Roles

Blarinomys breviceps consumes insects and is an important prey item for a range of avian and possibly reptilian species. Also, its burrows provide shelter to other small, gallery-forest species. (Davis, 1944; E and Wilson, 1993; Geise et al., 2008; Silva et al., 2003)

  • Ecosystem Impact
  • creates habitat

Economic Importance for Humans: Positive

There are no known positive effects of Blarinomys breviceps on humans.

Economic Importance for Humans: Negative

There are no known adverse effects of Blarinomys breviceps on humans.

Conservation Status

Silve et al. (2003) suggested that Blarinomys breviceps is extinct throughout much of its native range and is currently confined to mesic habitats in the Atlantic Forest. Although few specimens have been found at various locations throughout the Atlantic Forest, the IUCN Red List of Threatened Species lists B. breviceps as a species of "least concern". Due to its wide distribution and "presumed large population", there are not significant threats their their persistence. However, a potential threat to their survival is habitat destruction and fragmentation due to logging. (Abravaya and Matson, 1977; E and Wilson, 1993; Geise et al., 2008; Silva et al., 2003)

Contributors

Aaron Boje (author), University of Oregon, Stephen Frost (editor), University of Oregon, John Berini (editor), Animal Diversity Web Staff.

Glossary

Neotropical

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

World Map

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.

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.

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.

rainforest

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.

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

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

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

vibrations

movements of a hard surface that are produced by animals as signals to others

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

Abravaya and Matson, 1977. Blarinomys breviceps. Mammilian Species, 74: 1-3.

Abravaya, J., J. Matson. 1975. Contributions to Science, 270: 1-8.

Davis, 1944. The Capture of the Brazilian Mouse Blarinomys Breviceps. Journal of Mammalogy, 25/4: 367-369.

E and Wilson, 1993. Mammal Species of the World. Washington: Smithsonian Institution Press.

Eisenberg et al., , Musser et al., Reis et al., Silva et al., Pardinas et al.. 2008. "IUCN Red List" (On-line). Accessed October 20, 2010 at http://www.iucnredlist.org/apps/redlist/details/2827/0/full.

Geise et al., 2008. The karyotype of Blarinomys breviceps (Mammalia: Rodentia: Cricetidae) with comments on its morphology and some ecological notes. Zootaxa, 1907: 47-60.

Scheibler and Christoff, 2007. Habitat associations of small mammals in southern Brazil and use of regurgitated pellets of birds of prey for inventorying a local fauna. Brazilian Journal of Biology, 67/4: 619-625. Accessed October 20, 2010 at http://www.scielo.br/pdf/bjb/v67n4/04.pdf.

Silva et al., 2003. New distributional records of Blarinomys breviceps (Winge, 1888) (Sigmodontinae, Rodentia). Mammilia, 67/1: 147-152.