Gray Mouse Lemur - Ecology

Ecology

Like all other members of the family Cheirogaleidae, the gray mouse lemur is nocturnal and arboreal. It inhabits lowland tropical dry forest, sub-arid thorn scrub, gallery forest, spiny forest, eastern littoral forest, dry deciduous forests, semi-humid deciduous, moist lowland forest, transitional forest, and secondary forests or degraded forests (including plantations) all ranging up to 800 m (2,600 ft) above sea level. The species is more common in secondary forest than in primary forest, particularly bush and scrub habitat, where it occupies a "fine branch" niche, restricting the vertical range to fine branches, fine terminal supports, lianas and dense foliage. These lemurs are usually seen on branches less than 5 cm (2.0 in) in diameter. The gray mouse lemur tends to prefer lower levels of the forest and the understory, where branches and vegetation are dense.

In secondary forest, it is generally observed from ground level up to 10 m (33 ft) above ground, yet 15 to 30 m (50 to 100 ft) in the canopy of primary forest. Studies have found that the species can spend as much as 40% of its time below 3 m (10 ft), with 70% of its time spent at this level during the end of the dry season, when plant food is limited and insects compose a larger percentage of the diet. The species is more numerous in spiny forest, such as the Andohahela Special Reserve, than in the gallery forest, preferring drier, littoral forest, whereas the brown mouse lemur prefers inland rain forest.

The limits of the distribution are poorly understood. It is believed to range from the Onilahy River or Lake Tsimanampetsotsa in the south to Ankarafantsika National Park in the north. There is also an isolated and disjointed population in the southeastern part of the island, near Tôlanaro and the Andohahela National Park, up to the Mandena Conservation Zone. Individuals tend to occupy small home ranges of 1 to 2 ha (2.5 to 4.9 acres). The gray mouse lemur is also sympatric with the reddish-gray mouse lemur, golden-brown mouse lemur, Madame Berthe's mouse lemur, and several other cheirogaleid lemurs. In Ankarafantsika National Park, where it coexists with the golden-brown mouse lemur, the gray mouse lemur's relative population density was highest at higher altitudes and in drier habitat, while the golden-brown mouse lemur preferred the opposite. Another study has looked at the coexistence of the gray mouse lemur and Madame Berthe's mouse lemur and found small, exclusive clusters of each species and a high degree of feeding niche overlap.

The gray mouse lemur can reach high population densities up to several hundred individuals per square kilometer (up to 167 individuals/km2 at Ankarafantsika National Park to 712 individuals/km2 at Kirindy Mitea National Park). This abundance is not uniform and tends to concentrate in "population nuclei", suggesting that it is difficult to accurately estimate population densities when extrapolating from a small area (from various studies) to a large area. The difficulty in finding individuals during some times of the year, particularly during the dry periods, can further complicate the problem of estimating population densities.

Mouse lemurs are omnivorous, and favor fruit and insects for the bulk of their diet. The gray mouse lemur may even come down to the ground to catch insect prey, though it quickly returns to the protective cover of the understory to consume its catch. Nectar is also a part of the gray mouse lemur's diet, making it a potential pollinator for local plant species. A single instance of a male cannibalizing an adult female is known.