Although local traditions, such as fady, generally help protect lemurs and their forests, illegal logging, economic privation and political instability conspire to thwart conservation efforts.
[10] It was noted in 2012 that many sources had commonly and falsely assumed that Linnaeus was referring to the ghost-like appearance, reflective eyes, and ghostly cries of Madagascar's lemurs when he selected the name.
[25] Rafting has since been the most accepted explanation for the lemur colonization of Madagascar,[26][27] but until recently, this trip was thought to be very unlikely because strong ocean currents flow away from the island.
[28] In January 2010, a report demonstrated that around 60 mya both Madagascar and Africa were 1,650 km (1,030 mi) south of their present-day positions, placing them in a different ocean gyre, producing currents that ran counter to what they are today.
As the continental plates drifted northward, the currents gradually changed, and by 20 mya the window for oceanic dispersal had closed, effectively isolating the lemurs and the rest of the terrestrial Malagasy fauna from mainland Africa.
[29] However, early settlers quickly converted the forests to rice paddies and grassland through slash-and-burn agriculture (known locally as tavy), restricting lemurs to approximately 10% of the island's area, ~60,000 km2 (23,000 sq mi).
[33][43][44] According to Russell Mittermeier, the president of Conservation International (CI), taxonomist Colin Groves, and others, there are nearly 100 recognized species or subspecies of extant (or living) lemur, divided into five families and 15 genera.
Based on its anatomy, researchers have found support for classifying the genus Daubentonia as a specialized indriid, a sister group to all strepsirrhines, and as an indeterminate taxon within the order Primates.
[65][66][67] Indriids also have a specialized digestive system for folivory, exhibiting enlarged salivary glands, a spacious stomach, and an elongated caecum (lower gut) that facilitates fermentation.
Such traits include continuously growing, rodent-like front teeth for gnawing through wood and hard seeds; a highly mobile, filiform (filament-shaped) middle finger for extracting food from tiny holes; large, bat-like ears for detecting hollow spaces within trees;[17][29][51][70] and use of self-generated acoustical cues to forage.
With sportive lemurs, subspecies were traditionally defined based on slight morphological differences, but new genetic evidence has supported giving full species status to these regional populations.
[16] Male ring-tailed lemurs also have scent glands on the inside of their forearms, adjacent to a thornlike spur, which they use to gouge, and simultaneously, scent-mark tree branches.
This lemur can consume twelve times the typically lethal dose for most mammals on a daily basis; the physiological mechanisms that protect it from cyanide poisoning are unknown.
Although lemurs in captivity have been shown to be prone to hemosiderosis, the frequency of the disease varies across institutions and may depend on the diet, husbandry protocols, and genetic stock.
Sifakas have been observed eating soil from termite mounds, possibly adding beneficial intestinal flora to aid the digestion of cellulose from their folivorous diet.
[42][108] Although the mongoose lemur (E. mongoz) is the best-documented example, every species in the genus studied has shown some degree of cathemeral behavior,[71] although night activity is often restricted by light availability and moon periodicity.
[30][94][109] Other lemurs that do not exhibit dormancy conserve energy by selecting thermoregulated microhabitats (such as tree holes), sharing nests, and reducing exposed body surfaces, such as by hunched sitting and group huddling.
[113] Using their long, powerful back legs, they catapult themselves into the air and land in an upright posture on a nearby tree, with both hands and feet tightly gripping the trunk.
[56] Dietary regimes of lemurs include folivory, frugivory, and omnivory, with some being highly adaptable while others specialize on foods such as plant exudates (tree gum) and bamboo.
In the 1760s and 1770s, French naturalists Georges-Louis Leclerc, Comte de Buffon and Louis-Jean-Marie Daubenton began describing the anatomy of several lemur species.
However, the most notable contributions from this century includes the work of Alfred Grandidier, a naturalist and explorer who devoted himself to the study of Madagascar's natural history and local people.
Jean-Jacques Petter and Arlette Petter-Rousseaux toured Madagascar in 1956 and 1957, surveying many of its lemur species and making important observations about their social groupings and reproduction.
The Petters and Jolly spawned a new era of interest in lemur ecology and behavior and were shortly followed by anthropologists such as Alison Richard, Robert Sussman, Ian Tattersall, and many others.
Following the political turmoil of the mid-1970s and Madagascar's revolution, field studies resumed in the 1980s, thanks in part to the renewed involvement of the Duke Lemur Center under the direction of Elwyn L. Simons and the conservation efforts of Patricia Wright.
[141] Lemurs are threatened by a host of environmental problems, including deforestation, hunting for bushmeat, live capture for the exotic pet trade,[142] and climate change.
[61] Since the arrival of humans on the island approximately 2000 years ago, all endemic Malagasy vertebrates over 10 kg (22 lb) have disappeared,[37] including 17 species, 8 genera, and 3 families of lemurs.
[147] The IUCN reiterated its concern in 2013, noting that 90% of all lemur species could be extinct within 20 to 25 years unless a US$7 million 3-year conservation plan aimed at helping local communities can be implemented.
[135] All protected areas, excluding the private reserves, comprise approximately 3% of the land surface of Madagascar and are managed by Madagascar National Parks, formerly known as l'Association Nationale pour la Gestion des Aires Protégées (ANGAP), as well as other non-governmental organizations (NGOs), including Conservation International (CI), the Wildlife Conservation Society (WCS), and the World Wide Fund for Nature (WWF).
[160] One of their major projects involved the release of captive black-and-white ruffed lemurs, designed to help restock the dwindling population within Betampona Reserve.
[needs update] Captive lemur populations are maintained locally and outside of Madagascar in varied zoological conservatories and research centers, although the diversity of species is limited.