Grey Mouse Lemur

Quick Take

• This tiny primate looks exactly like a mouse, yet its biology is closer to yours than you'd expect. See the human connection →
• Before winter hits, this lemur does something extreme to its own body that most animals never attempt. Discover their torpor survival →
• Despite fitting in your palm, this animal can cover a distance that would surprise most seasoned wildlife experts. Explore their movement range →
• In grey mouse lemur society, males don't run things, and the social structure is even stranger than that fact suggests. See the female-led society →

Grey mouse lemurs, also called lesser mouse lemurs, are among the smallest primate species in the entire world. Even though their size, color, and body shape are reminiscent of a common mouse, they are very different from rodents in physiology and genetics. As primates, they actually have promising applications for non-invasive research into conditions that also impact humans.

While they are not considered endangered, this species is only found in select habitats around the western and southern sides of the African island of Madagascar. They are industrious nocturnal foragers who exhibit plenty of interesting dynamics and characteristics, including a prolonged state of torpor and hibernation and female-dominant group structure.

3 Incredible Grey Mouse Lemur Facts

• Grooming Claw: While almost all of their digits are equipped with a flat nail, these lemurs have one long claw on their hind foot to aid in grooming.
• Long Jumpers: Even though they are small enough to fit into the palm of a human hand, these little primates can leap up to 9.8 feet (3 meters) in a single bound.
• Community Sleeping: Adult females routinely congregate for their daytime sleeping with related females and their offspring.

Classification and Scientific Name

Grey mouse lemurs, alternatively spelled gray, are also known as lesser mouse lemurs due to their small stature. Their scientific name is Microcebus murinus. The genus name comes from the Greek words ‘mikros’ and ‘kebos,’ which mean ‘small’ and ‘monkey,’ respectively. The species name murinus is a derivative of the Latin word for mouse. This species is part of the Cheirogaleidae family in the Mammalia class of animals.

Appearance

These animals have an extremely small stature and are one of the smallest primate species in the world. They are generally mouse-like in appearance and size, with tails that are often longer than the rest of their body. Adult body length ranges from 4.7 to 5.5 inches, and tail length is 5.1 to 5.9 inches. Total weight is usually only around 2.0 to 2.4 ounces or 58 to 67 grams. There is little difference in size or body type between males and females.

Grey mouse lemurs have gray to brown fur that can have red overtones. They have short limbs and pronounced, rounded ears protruding from the top of their head. They have flexible hands and feet capable of grasping branches and limbs firmly. Their facial features are similar to other lemurs, including a long snout-like nose that also gives them a keen sense of smell.

These lemurs also have large, round eyes that provide strong night vision to aid them in their nocturnal foraging habits. They have a specialized layer of tissue, called the tapetum, behind the retinas of their eyes, as do many other animals. This helps them capture as much light as possible to improve night vision and also makes their eyes very reflective when exposed to a bright light source, like a flashlight.

Behavior

Even though they are generally solitary foragers, grey mouse lemurs do have strong community dynamics and frequently communicate with one another. Adults can emit a sharp whistling sound to alert nearby lemurs of a threat, but the duration is quite short to prevent predators from pinpointing their location. They also use several other types of whistling sounds to ensure there is an acceptable distance between individuals or in displays of aggression between two adults.

Like many of its close taxonomic relatives, this lemur can enter a state of torpor where its metabolism slows considerably. This state is comparable to hibernation in other animal species and allows them to conserve energy. Grey mouse lemurs typically engage in long-term torpor during the colder months of May through August. They can also reduce the metabolic rate on a short-term basis when they sleep during the daylight hours.

Habitat

Like other lemurs, this species is only found on the African island of Madagascar. It is considered the most widespread and numerous lemur, even though it’s only found in dry, deciduous forest habitats along the western side of the island. They are found in all kinds of dry wooded areas throughout their range, including scrublands, gallery forests, moister lowland forests, and degraded forests around plantations. They can thrive at elevations of up to 2600 feet above sea level.

The grey mouse lemur spends most of its time foraging, sleeping, and traversing the branches and limbs of trees. It tends to move around on all fours and is an adept climber and jumper. Despite their extremely small stature, they can leap distances of almost 10 feet in order to capture insects or cross the gap to another tree. While they do prefer to stay up in the trees, they can occasionally be seen on or near the ground in their search for food.

Diet

These lemurs are omnivores that target various insect species and all kinds of plant material. They are nocturnal foragers that wander around a designated home range that usually ranges from 2.5 to 5 acres in size. They are known to increase their consumption in the weeks leading up to their long-term dormant state. To prepare for torpor, grey mouse lemurs pack fat into their hindquarters and tail, increasing their tail size up to fourfold.

What do grey mouse lemurs eat?

Insects are often the main component of a grey mouse lemur’s diet. Local beetle species are a favored target. They are also known to consume frogs, chameleons, and other small reptiles. These tiny primates also get plenty of plant matter in their diets, including fruit, leaves, and flowers from local trees or shrubs. They may also consume nectar, which makes them a potential pollinator as well.

Predators and Threats

The grey mouse lemur is currently considered a species of least concern in terms of conservation, although though this assessment is based on limited data regarding population numbers and trends. Predatory birds are among the chief predators of this species, particularly the Madagascan owl, barn owl, and Henst’s goshawk. These small mammals may also fall prey to snakes, fossa, and several local mongoose species. Lemurs frequently release alarm calls to warn others about impending threats and occasionally mob potential predators to chase them away.

Aside from the many natural dangers found in the forests of Madagascar, they also face threats from human activity, including poaching and trapping for the pet trade. Logging and expansion of human development around the island have also degraded or destroyed parts of their native range. Harsh agricultural techniques and the expansion of cattle farming are among the chief threats to habitat quality.

Reproduction, Babies, and Lifespan

Grey mouse lemurs have a complex and unusual social structure for primates. Females tend to congregate in central locations with their young and exert influence over males in terms of breeding selection and food availability. This indicates a female-dominant hierarchy. Individual adults have home ranges, and males tend to be more spread out with larger turfs than individual females. Females and their offspring typically sleep alongside related adult females during the day but may also spend the day alone if they have no relatives nearby.

Reproduction occurs from September to March, and there is no strict male-female pairing during this period. An adult female is usually able to breed for a period of 1 to 2 months during this season. Gestation can last anywhere from 54 to 68 days before the female gives birth to 2 or 3 pups. Babies remain in the nest for about 3 weeks, then the mother starts bringing them with her during foraging expeditions.

Lemurs are generally able to forage independently by the time they are 2 months old and are sexually mature in 1 to 2 years. Females generally have a limited reproductive span of about 5 years but can live for much longer after that. Individuals in captivity have been reported to reach over 15 years of age.

Population

Despite their small geographical range and declining population, the grey mouse lemur is not considered at imminent risk of extinction. They do have some flexibility and durability when it comes to ecological change. This gives it an edge over other small lemur species when it comes to immediate threat from habitat loss. Many individuals live in Madagascar’s numerous reserves and protected areas, which gives them some stability.

Grey Mouse Lemur In the Zoo

These lemurs are not generally kept as zoo animals, but they are used in non-invasive and non-lethal research due to genetic similarities with humans. The Duke Lemur Center is home to one of the only breeding populations of grey mouse lemurs in the world. As of 2020, their colony included dozens of mature individuals with a balanced population of males and females.