By Christee Means
Geographic Range
The Amazon dwarf squirrel is found in South America. It ranges from the Amazon Basin of Colombia, Ecuador, Peru, and Brazil, west of the Rios Negro and Madeira, up to 2,000 m in elevation (Emmons, 1997).
Biogeographic Regions:
neotropical 
(native ).
Habitat
(6560 ft)
These squirrels inhabit lowland to dense, fog-shrouded forests, but seem to prefer palm forests (Nowak, 1999). The Amazon dwarf squirrel uses all levels of the forest, from ground level to the canopy (Emmons, 1997). Major activities of this squirrel are confined to heights under 5 meters, using mainly rough, vertical trunks (Youlatos, 1999).
These animals are found in the following types of habitat:
tropical .
Terrestrial Biomes:
rainforest .
Physical Description
The total length of the Amazon dwarf squirrel is 250-273mm (Eisenburg and Redford, 1989). The tail is usually shorter than the head and body length; it is relatively slender, tapered toward the tip and frosted with a dirty white color (Nowak, 1999). The upper parts of the Amazon dwarf squirrel are mostly brown, finely grizzled, and reddish to olive in color. The ventrum is thickly haired, deep to pale orange, with brightest coloration on the chest. The ears are short, not protruding above the crown of the head. The fur behind the ears is pale yellow with short hairs not visible above the rim of the ear (Emmons, 1997).
Some key physical features:
endothermic ; bilateral symmetry .
Reproduction
These squirrels may breed from April to June, as do congeneric animals.
There are no data on the mating system of this animal.
Although data are lacking on the reproduction of this species, it is reasonable to assume that the young, like most squirrels, are altricial. M. alfari, a closely related species, breeds at least from late April to June, and this may also be the case with M. flaviventer. One female M. flaviventer was found to have two embryos (Nowak, 1999).
Key reproductive features:
iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (internal ); viviparous .
As in all mammals, the female provides parental care by nourishing her young with milk. It is likely that, as in other squirrels, the young are born in a nest of some sort, with their eyes closed. The mother likely cares for the young in the nest until they are able to venture forth on their own.
Parental investment:
altricial ; female parental care .
Lifespan/Longevity
There are no data available on the lifespan of M. flaviventer.
Behavior
Amazon dwarf squirrels are primarily diurnal. Although usually solitary, these squirrels can be seen in pairs especially during the mating season (Emmons, 1997). They primarily use clawed locomotion to travel and feed, associated with large vertical support use. Quadrupedal bounds and vertical leaps are also common. Claw cling, or hanging on rough surfaces, was the dominant feeding posture occuring on vertical supports (Youlatos, 1999). Amazon dwarf squirrels make nests that consist of a ball of leaves lined with fibers (Emmons, 1997). They have a reputation of being rather curious and can be approached within a short distance before they retreat (Nowak, 1999).
Food Habits
The Amazon dwarf squirrel forages for arthropods by searching actively over large trunks, vines, and treefalls. They also feed on a substance that is scraped from the bark of trees (Emmons, 1997). They also feed on fruits and nuts of palms (Nowak, 1999).
Primary Diet:
carnivore (insectivore ).
Predation
In general, small rodents are frequently on the menu for carnivores, birds of prey, and oportunistic carnivorous animals of all sorts. Although there are no specific reports of predation on this species, it is reasonable to assume that they are prey items.
Ecosystem Roles
The roles that M. flaviventer plays are unknown at this time.
Economic Importance for Humans: Negative
No negative impact of this species has been reported.
Economic Importance for Humans: Positive
The economic importance of these squirrels has not been evaluated.
Conservation Status
M. flaviventer currently has no special conservation status. However, because it is an inhabitant of threatened rainforests in the Amazon River basin, this may not always be the case.
For More Information
Find Microsciurus flaviventer information at
Contributors
Christee Means (author), University of Wisconsin-Stevens Point.
Chris Yahnke (editor), University of Wisconsin Stevens Point.
