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).
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).
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).
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).
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.
There are no data available on the lifespan of M. flaviventer.
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).
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).
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.
The roles that M. flaviventer plays are unknown at this time.
The economic importance of these squirrels has not been evaluated.
No negative impact of this species has been reported.
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.
Christee Means (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.
living in the southern part of the New World. In other words, Central and South America.
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.
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.
an animal that mainly eats meat
uses smells or other chemicals to communicate
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.
parental care is carried out by females
union of egg and spermatozoan
An animal that eats mainly insects or spiders.
fertilization takes place within the female's body
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).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
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.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
Eisenburg, J., K. Redford. 1989. Mammals of the Neotropics Vol.1. Chicago, IL: University of Chicago Press.
Emmons, L. 1997. Neotropical Rainforest Mammals. Chicago, IL: The University of Chicago Press.
Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore and London: The John Hopkins University Press.
Youlatos, D. 1999. Locomotor and postural behavior of *Sciurus igniventris* and *Microsciurus flaviventer* in eastern Ecuador. Mammalia, 63(4): 405-416.