The Brown mouse lemur is amongst the smallest species of lemur in the world. Considered a gray mouse lemur subspecies until 1977, it was then reclassified as its own species. It is also known as the Eastern rufous mouse lemur, the Rufous mouse lemur, or the Russet mouse lemur. Its dorsal side is brown or reddish-brown, while ventrally it is a whitish-grey. It is under threat of extinction because of habitat in the marshes of forests where it lives.
The range of the Brown mouse lemur includes areas in the north and east of Madagascar. They occur in the many parts of Madagascar that are protected, including Ranomafana National Park, Montagne d’ Ambre National Park, Zahamena Nature Reserve and Marojeiy Nature Reserve. These lemurs live in primary and secondary forest areas, including secondary bamboo forests and the forest fringes of coastal rainforests.
Brown mouse lemurs are strictly nocturnal and live solitary lives, apart from during the breeding season, and mothers with their babies. During the day they sleep in tree holes or in nests in large groups of females with their dependent offspring. These lemurs maintain an extended harem system. The territories of males are around 200 meters in diameter, overlapping two or more female territories. Subdominant males are found on the edges of the territories of dominant males. Females have home ranges that are slightly smaller than the ones that males have. From May through September, this species is in a state of torpor, during which they can lose 5 to 35 g of weight and their tail circumference decreases from 4 to 12 mm, the latter change because their tail is a major reservoir of fat, and during torpor their reserves are depleted. Females usually stay in torpor for longer than males.
Brown mouse lemurs are polygynous, which means that one male mates with multiple females. A ritualistic courtship before mating involves a male making soft squeaking calls and lashing his tail to attract a female. The mating season is from September to October. Gestation lasts for about 60 days and births generally take place in November and December, 1 to 3 offspring being born per litter. Weaning takes place at about 2 months of age, and in captivity, females may give birth to 2 litters per year. A developing offspring will start to play with its mother, by chasing her and jumping onto her hands and feet, helping it to develop its locomotion skills. In the winter following their birth, males leave the areas where they were born. Brown mouse lemurs are sexually mature after the age of one year.
The primary threat to Brown mouse lemurs is loss of habitat due to slash-and-burn methods. They are also threatened within their habitat by natural predators.
The IUCN Red List and other sources do not provide a number for the Brown mouse lemur total population size. However, according to the IUCN Red List, around 7,762 individuals have been estimated within Ranomafana National Park. Currently Brown mouse lemurs are classified as Vulnerable (VU) and their numbers today are decreasing.
Brown mouse lemurs have an important role in dispersing the seeds from the fruits they eat. As prey for other species, they may also have an effect on predator populations.