Blarinomys breviceps

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.

• Biogeographic Regions
• neotropical neotropical
  • native native

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.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• rainforest rainforest

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

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,

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

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.

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).

• Key Behaviors
• fossorial fossorial
• diurnal diurnal
• motile motile
• solitary solitary

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).

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.

• Perception Channels
• visual visual
• tactile tactile
• vibrations vibrations
• chemical chemical

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).

• Primary Diet
• carnivore carnivore
  • insectivore insectivore

• 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.

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.

• 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.

Additional Links

Encyclopedia of Life

Contributors

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

References

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

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

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.