Eastern Woolly Lemur, Avahi laniger
EASTERN WOOLLY LEMUR
Avahi laniger
Geographic Distribution and Habitat
The eastern woolly lemur (Avahi laniger), also known as the eastern avahi or Gmelin’s woolly lemur, is a native of the large island country of Madagascar. Situated about 249 mi (400 km) off of Africa’s southeastern coast in the Indian Ocean, Madagascar is home to species found nowhere else in the world and is regarded by conservationists as a world biodiversity hot spot.
As their name suggests, eastern woolly lemurs occupy Madagascar’s eastern coast, where they reside in tropical moist lowland and montane rainforests. Average elevation is from 2,625 to 6,562 ft (800–2,000 m). The species can also be found in secondary forests, having found a way to thrive in these disturbed habitats.
Eastern woolly lemurs’ highest concentration is in the northeast, with a range that extends from the Bemarivo River in the north to the Nosivolo/Mangoro rivers in the south. Included in this range are several national parks and wildlife reserves. (Until recent taxonomic rankings “split” the species, resulting in the identification of new lemur species, scientists had assigned nearly the entire length of Madagascar’s eastern coastline to eastern woolly lemurs.)
Two subspecies of the eastern woolly lemur have been identified: Avahi laniger laniger of eastern Madagascar, and A. laniger occidentalis of northwestern Madagascar. Apart from their respective geographic locations and slight behavioral differences, however, some wildlife biologists do not consider these two subspecies to be distinct.
Size, Weight, and Lifespan
Woolly lemurs are the smallest members of the primate family classified as Indriidae. Eastern woolly lemur adults weigh between 1.3 and 2.8 lb (0.6–1.3 kg) with a head-to-body length between 11.8 and 17.7 in (30–45 cm). Their tails add another 12.9–14.6 in (33–37 cm) to their small bodies. The two sexes are pretty close in size, though males have slightly larger skulls and larger molars (if you happen to be peeking inside their mouth).
Lifespan in the wild is unknown. It is known that in captivity, these animals fare poorly. Zoos have had dismal success in caring for them. Captured eastern woolly lemurs who are taken out of Madagascar are reported to survive no longer than three months.
The lifespan of another member of the Indriidae family, Coquerel’s sifaka (Propithecus coquereli), is reported to have lived for 30.5 years in captivity. Other sifaka (Propithecus) species have lived for more than 20 years in captivity. The lifespans of these “primate cousins” give some insight, scientists believe, to the possible lifespan of eastern woolly lemurs. However, that these individuals were held captive for 20 to over 30 years is a somber thought.
Appearance
Seriously, have you ever seen such a cute little face? Enormous brown eyes (almost owl-like) feign a look of permanent wide-eyed amazement. Behind the retina of each eye is a light-reflecting layer called the tapetum lucidum (characteristic to prosimians), which can give the ethereal effect of “eye shine” and helps lemurs to see in the dark. Scalloped ears demurely appear through the thick fur that covers a small rounded head. A dark, moist muzzle (characteristic of strepsirrhine primates) sits modestly in the center of a furry face.
In contrast to other members of the family Indriidae, who have silky fur, a dense “woolly” coat cloaks the compact bodies of eastern woolly lemurs. Their pelage (coat) color is either russet or grayish brown, with a white fur stripe decorating each flank.
Diet
Eastern woolly lemurs are herbivores with a strong folivorous inclination. That’s just a fancy way of saying that these primates are vegetarians who eat lots of leaves, especially young leaves. They eat only the leaf blade, ignoring the midrib (central, thick linear structure, or “vein”) and the petiole (the stalk that joins a leaf to a stem; leafstalk). Fruits are also on their rainforest menu (which makes these lemurs frugivorous as well as folivorous!). They also eat buds, twigs, tree bark, and, on occasion, flowers.
Favored plants for leaves, buds, and twigs include the following species: Harongana madagascariensis, commonly known as the dragon’s blood tree or orange-milk tree; Hafotra; Hafidahy; Varongy; Voara; Fatsikahitra; Malambovany; Rotra; Rahiaka; Mahanoram; Sary; Karambitoma; and Fohaninasity.
Fruit plants include the species Rheedia; the lemurs favor the species Erythroxylum for its flowers.
A habitat neighbor and a closely related species—the indri (Indri indri), Madagascar’s largest lemur at 15 lb—shares a diet similar to that of the eastern woolly lemur. But the activity patterns of the two species are opposite: indris are diurnal (active during daylight hours), whereas eastern woolly lemurs are nocturnal (active during the night). Any potential conflicts (food fights) are therefore avoided. The sportive lemur (Lepilemur) isn’t so lucky. In areas of shared habitat, eastern woolly lemurs give the boot to sportive lemurs, displacing them from favored food sources.
Young eastern woolly lemurs learn which foods to eat by playfully snatching food from their mother while she is eating. By chewing on that stolen twig, they discover which foods are safe and tasty.
Behavior and Lifestyle
As nocturnal creatures, eastern woolly lemurs are active during the nighttime. They are arboreal, spending the majority of their time in trees. To travel, they leap vertically from tree to tree with an average distance of 6 ft (1.8 m), briefly alighting on branches that are barely over 1 in (3 cm) in diameter. Wildlife biologists have observed a wide range of hip movements as these lemurs propel themselves forward. The species’s long tail assists with balance. To support their weight while feeding, eastern woolly lemurs cling to the trunks of trees with their strong legs. Feeding times are concentrated in the two hours after dusk and the two hours before dawn and occur at the top and outer boundary of a small leafy group of trees. Feeding heights range from 6.6 to 29.5 ft (2–9 m) with an average traveling height of 17 ft (5.2 m).
Should they descend to the ground, these lemurs do so slowly with downward leaps or quadrupedal movements from tree trunk to tree trunk. Upon the ground, they land with both feet together, standing erect and holding their arms overhead, much like a sifaka (another leaf-eating lemur known for its spectacular leaping)—or like the stance of a referee signifying a touchdown in the game of American football! Once on the ground, eastern woolly lemurs travel by hopping bipedally.
Traveling (foraging for food) and feeding account for about 25 percent of their time, while resting accounts for nearly 60 percent of their time. Because the diet of eastern woolly lemurs has limited nutritional value, these marathon naps are necessary, wildlife biologists believe, to conserve the lemurs’ energy. Nighttime naps occur at the center of tree crowns or on lianas (long-stemmed woody vines that “climb” up trees) beneath the canopy at heights from 6.6 to 33 ft (2–10 m).
During the day, when the rainforest’s diurnal creatures are waking up, eastern woolly lemurs are going to bed. They sleep huddled together within clumps of dense foliage or vines at the center-bottom crown of trees at a height of 6.6–29.5 ft (2–9 m).
Eastern woolly lemur’s genus name, Avahi, refers to their high-pitched defensive call.
Some wildlife biologists posit that the nocturnal eastern woolly lemur species likely evolved from a diurnal ancestor.
Scientists speculate that lemurs floated from mainland Africa to the island of Madagascar eons ago on rafts of vegetation.
“Lemur,” the genus name, means “ghost” or “spirit of the night” in Latin. Legend holds that 16th century Portuguese explorers to Madagascar were awakened, deep into the night, by the lemurs’ howls. The animals’ flickering eyes further convinced the unhinged explorers that these beings were the ghosts of their dead companions. Thus, they dubbed these ethereal creatures “lemurs.”
In the Malagasy language, the island of Madagascar is called “Madagasikara” and its people are referred to as Malagasy. The island’s appellation “Madagascar” is not of local origin but rather was popularized in the Middle Ages by Europeans.
Lemurs belong to the oldest and most primitive order of primates, known as prosimians, and belong to the suborder known as Strepsirrhini. Others belonging to this suborder include galagos (or bush babies), lorises, and pottos; characteristically, these animals have moist areas around their nostrils, or snout (similar to the noses of dogs and cats).
Highly social animals, eastern woolly lemurs live in family groups (known as “troops” in the nonhuman primate world) composed of a monogamous breeding pair and up to several generations of their offspring. Average group size is two to five individuals. Members of a troop form long-lasting bonds with one another.
Reportedly, the monogamous pair do not travel or forage together. They do, however, stay in touch with one another through long-distance contact calls.
Apparently, little time is devoted to social grooming: as little as 5 percent of their activity budget, according to early wildlife studies. Yet . . . Mother Nature has equipped eastern woolly lemurs with the perfect accoutrements for this activity. A grooming claw on the second digit of each foot is ideal for scratching an annoying itch. And a unique morphological adaptation known as a tooth (or dental) comb—formed at the front of the lower jaw by forward-tilting lower incisors and lower canine teeth—is a grooming tool that any rainforest barber would love to have.
Home range for this territorial species is between 2.5 and 4.9 a (1–2 ha) and does not overlap with the home range of other groups. If necessary, however, eastern woolly lemurs will chase away and aggressively defend their home range from interlopers.
Besides the indri and the sportive lemur, other lemur species who occupy the same rainforests as eastern woolly lemurs include the diademed sifaka (Propithecus diadema) and the red-bellied lemur (Eulemur rubriventer).
Natural predators are here, too. Through their secretive nature and diminutive size, eastern woolly lemurs do their best to avoid becoming a meal. Unfortunately, their daytime slumber leaves them vulnerable to diurnal raptors. Henst’s goshawks (Accipiter henstii)—large birds of prey who are known to perch on an exposed branch and scan the forest for prey—ambush the lemurs while they sleep. Owls (Strigiformes) are also a threat to eastern woolly lemurs.
Modes of communication include vocalizations, olfactory cues, posturing, and tactile activity.
The following calls are included in eastern woolly lemurs’ vocal repertoire:
- Infant call: a plaintive, whistle-like sound that an infant emits to get her mother’s attention.
- Alarm call: begins as a faint, discreet grunting sound followed by a weak snorting sound. Emitted by an individual to indicate mild irritation. May transform into a cooing call.
- Trembling call: A loud, defensive call with a rising pitch, sounded in a rapid manner and ends on a powerful high-pitched note. Emitted by an individual who is mightily irritated or disturbed. The call sounds like “Ava Hy,” and gives this primate its genus name, Avahi.
- Distant communication call: Composed of high-pitched and modulated prolonged whistles. Announces location; emitted between a monogamous pair while one travels and forages at night. Individuals also use these calls to communicate territorial borders.
- Cohesion call: A sudden, high-pitched call emitted by an individual who is separated from another by a distance of 50 m, following a situation that has caused alarm.
Eastern woolly lemurs use olfactory communication to convey specific information, including the demarcation of territorial borders and messages to potential predators to “keep away.” Specialized scent glands on the neck of each sex allow them to leave these olfactory cues.
Posturing, or physical displays, may include chasing away outsiders from a troop’s territory.
Tactile communication (touching) is common between members of a family group.
Most wildlife biologists conclude that the eastern woolly lemur is a monogamous species. Breeding season is from March to May, with the majority of births occurring in August and September. After a gestation period (pregnancy) of 120 to 150 days (average of 135 days), a mother gives birth to a single offspring (twins are rare).
Infant woolly lemurs develop slowly and are carried by their mothers, close across her ventral side (stomach), for their first two months of life. Gradually, they move to ride on her dorsal side (back) as she travels. Mothers nurse their infants three to four times a day, oftentimes napping during these lengthy sessions. Infants are considered weaned at 6 months of age, an event that coincides with the following wet season. They’ve learned which foods to eat by observing their mother grabbing and playing with her food. They now follow her through the forest, grasping onto branches. Infants have been known to fall up to 30 ft (9 m). Eventually, they learn to judge distances and make long leaps. At one year of age, young eastern woolly lemurs are considered independent, able to feed and travel on their own. However, even after becoming independent, they choose to remain close by their mother.
Mothers appear to be the primary caregivers, but fathers remain close by.
The interbirth interval for this species is unknown.
Wildlife biologists posit that, through their folivory (leaf-eating), eastern woolly lemurs may influence plant composition in the forests where they live. It’s also possible that through their limited frugivory (fruit-eating) they play a small role in seed dispersal, thereby helping to regenerate their forest habitat.
The eastern woolly lemur is categorized as Vulnerable by the International Union for Conservation of Nature (IUCN, 2019), appearing on the IUCN Red List of Threatened Species. In 2008, the species had been categorized as Least Concern. This increase in threat level is a potential harbinger: the IUCN predicts a more than 30-percent decline in the overall population over a three-generation epoch of 30 years. Unless the threats against eastern woolly lemurs are resolved, eastern woolly lemurs will become endangered and, possibly, extinct.
Habitat loss is the primary threat against this species. Slash-and-burn agriculture and the logging industry have destroyed pristine tracts of forests where these lemurs live and raise their families.
Eastern woolly lemurs are also hunted and killed for their flesh, known as “bushmeat.” Hunters set traps, baited with fruit. Or they might use a slingshot or spear to take down a napping lemur from its daytime sleeping site. In Makira Forest, the carnage has been especially high; between 2,500 and 3,000 individuals have been killed by hunters annually.
Paradoxically, killing these animals, particularly a mother and her infant, is regarded in ancient Malagasy culture as “fady” or “taboo.” Taboos are believed to be enforced by supernatural powers, and are particularly connected with Malagasy ancestor worship.
Then how is it that so many eastern woolly lemurs are killed? Some tribes have a fady (or taboo) against hunting lemurs. Other tribes have a fady against eating lemur meat. So, one tribe hunts (not a fady) and sells the meat (for a profitable transaction) to the other, for whom eating the meat is not fady.
Fady can also mean “sacred.” As example, Madagascar’s large indri lemurs (also known as babakotos) are fady (sacred) for some Madagascans (or “Malagasy,” as the island’s residents are called), who believe the spirits of their ancestors inhabit the bodies of these extra-large lemurs.
Unfortunately, any fady belief or practice is not helping the survival of eastern woolly lemurs. Serious conservation efforts are required.
The eastern woolly lemur is listed in Appendix I of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments whose goal is to ensure that international trade in specimens of wild animals and plants does not threaten their survival. However, as is often the case with endangered species, laws created to protect them are largely ignored and difficult to enforce.
The creation of a new national park in 2012 may offer some optimism for the species survival. Makira Forest, a “killing ground” for many years, became Makira Natural Park and was officially inaugurated by the government of Madagascar in 2015. The park spans more than 92,000 acres, or 1,438 sq m (372,470 hectares), of low and mid-altitude tropical rainforest and is home to 20 species of lemurs, including eastern woolly lemurs and four critically endangered species: the indri, the silky sifaka, the red-ruffed lemur, and the black-and-white ruffed lemur. More than 50 percent of Madagascar’s plant species thrive here.
Created by the Malagasy government, Wildlife Conservation Society, and other partners, Makira National Park represents the first protected area (IUCN, Category II) in Madagascar’s national network of 95 new terrestrial and marine protected wilderness areas.
Eastern woolly lemurs have also reported within Mananara-Nord, Mantadia, Marojejy, and Zahamena national parks; within two strict nature reserves, Betampona and Zahamena (a strict nature reserve is the highest category, and IUCN designation, of a protected wilderness area), and within five special reserves, Ambatovaky, Ambohitantely, Analamazaotra, Anjanaharibe-Sud, and Mangerivola (IUCN, 2014).
SOS Lemurs (or Save Our Species – Lemurs) is a conservation group founded to protect lemur populations and preserve their habitat. The group is currently working on a lemur conservation strategy with the IUCN’s Species Survival Commission. This five-year initiative (2017–2021) is funded by a Geneva-based private foundation. Initiatives include facilitating community education programs that foster appreciation for Madagascar’s lemurs; establishing livelihood alternatives to help local citizens coexist with the lemurs, instead of hunting them; and supporting local conservation groups and nongovernment organizations (NGOs) to develop and achieve long-term goals for saving lemur species from extinction.
Biodiversity Conservation Madagascar (BCM) protects habitat and provides employment to local communities to help save lemurs across Madagascar. Through conservation leases granted through Madagascar’s government, the organization has worked to protect forest lands since 2003.
Wildlife biologists have declared lemurs the most threatened mammal group on earth, due to the combined pressures of hunting and habitat loss. They further assert that only a coordinated conservation initiative can save the world’s lemurs from forever vanishing.
- https://www.iucnredlist.org/species/2434/16114949
- http://www.theprimata.com/avahi_laniger/
- http://pin.primate.wisc.edu/factsheets/entry/indri
- https://animaldiversity.org/accounts/Avahi_lanigerhttps://animaldiversity.org/accounts/Indriidae
- https://madagascar.wcs.org/Wild-Places/Makira-Natural-Park.aspx
- https://www.lemurreserve.org/lemurs/eastern-woolly-lemur
- https://programs.wcs.org/newsroom/News-Releases/articleType/ArticleView/articleId/6770/categoryId/178/Government-of-Madagascar-Inaugurates-Makira-Natural-Park.aspx
- https://www.saveourspecies.org/news/lemurs/sos-lemurs-saving-madagascars-iconic-species
- https://www.lemurconservationnetwork.org/category/organization/lemur-species/woolly-lemurs/ahavi-laniger/
- https://www.madamagazine.com/en/fady
- https://en.wikipedia.org/wiki/Eastern_woolly_lemur
- https://en.wikipedia.org/wiki/Indriidae
- https://en.wikipedia.org/wiki/Woolly_lemur
- https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/leaf-protein
- https://www.lemurconservationnetwork.org/category/organization/lemur-species/woolly-lemurs/ahavi-laniger
- http://animalia.bio/eastern-woolly-lemur
- https://animals.fandom.com/wiki/Eastern_Woolly_Lemur
- https://www.madacamp.com/Eastern_woolly_lemur
- https://www.britannica.com/science/dental-comb
- http://www.keeperblog.org/2011/12/what-makes-a-lemur-a-lemur
- https://en.wikipedia.org/wiki/Liana
- https://academic.oup.com/jmammal/article/85/3/420/900401
Written by Kathleen Downey, April 2020