Milne-Edwards’ Sifaka, Propithecus edwardsi

MILNE-EDWARDS'S SIFAKA

Propithecus edwardsi

Geographic Distribution and Habitat

The Milne-Edwards’s sifaka, also known as the Milne-Edwards’s simpona or Edwards’s sifaka, is a large lemur species found only on the island of Madagascar. Historically, they occupied a large corridor of southeastern rainforest, spanning the Mangoro and Onive rivers in the north all the way down to the Andringitra mountains in the south. However, decades of widespread human activity and climate change have extirpated them from much of their native habitat.

Today, they’re reduced to isolated subpopulations scattered across protected areas such as Ranomafana National Park, Andringitra National Park, and forest fragments connected by the Corridor Forestier Ambositra-Vondrozo (COFAV). Beyond these refuges, deforestation, slash-and-burn agriculture, and logging continue to shrink their viable range around Ranomafana, Kianjavato, and Ambatovaky, as well as parts of the Fianarantsoa and Vatovavy-Fitovinany provinces.

Preferring primary rainforests perched between 1,640 and 4,920 feet (500 to 1,500 m) above sea level, Milne-Edwards’s sifakas live at higher altitudes than most other lemurs. The mature, undisturbed montane forests are markedly cooler than the lowland tropics, with daytime temperatures often hovering between 50 to 68°F (10 to 20°C) and dipping lower at night. Although Milne-Edwards’s sifakas are known to move into secondary or regrowing forest areas, long-term research indicates they struggle to meet their specialized needs in these disturbed habitats.

TAXONOMIC NOTES

Taxonomies are hypotheses about how we think species are related, and they change as we find new evidence and new tools to reclassify them. Milne-Edwards’s sifakas exemplify how fluid taxonomy can be, with its classification updating amid new evidence over more than a century.

Milne-Edwards’s sifakas belong to the Indriidae family of strepsirrhine primates (“wet-nosed” primates that include lemurs, lorises, and galagos). These are medium-to-large-sized lemurs distinguished by having only four teeth in their tooth comb instead of the usual six. The Indriidae family contains 19 species divided into three genera:

  • Indri (Indri), 1 species
  • Avahi (woolly lemurs), 9 species 
  • Propithecus (sifakas), 9 species

The Propithecus genus is further divided into two groups: the P. diadema group and the P. verreauxi group. The Milne-Edwards’s sifaka is part of the P. diadema group—four closely related, large-bodied sifakas found in Madagascar’s eastern rainforests. The other three members of this group are the diademed sifaka (P. diadema), Perrier’s sifaka (P. perrieri), and the silky sifaka (P. candidus).

When the species was first discovered in 1871, the Milne-Edwards’s sifaka was considered a distinct species. However, in subsequent years, some taxonomists reclassified them as a subspecies of their more flamboyantly colored cousin Propithecus diadema, due to perceived superficial differences between them, especially their coat colors. For decades, they were called “P. diadema edwardsi.” In 2004, analyses of morphology and DNA profiles led to its reinstatement as a valid species with its own ecological and conservation needs.

Milne-Edwards's sifaka range, IUCN 2025

Size, Weight, and Lifespan

Males and females are monomorphic—virtually indistinguishable from each other aside from their reproductive parts. Among the largest living lemurs, on average they reach a head-body length of about 17.7 to 19.7 inches (45 to 50 cm). Their non-prehensile tails are nearly as long, ranging 16.5 to 18.9 inches (42 to 48 cm). That’s about 94% of their head and body length!

Females tend to be slightly heavier, averaging 12.6 to 14.3 pounds (5.7 to 6.5 kg), while males weigh in around 12.1 to 13.9 pounds (5.5 to 6.3 kg). This is unusual among mammals, where sexual dimorphism (size and appearance differences between sexes) is more common.

In captivity, Milne-Edwards’s sifakas have been known to live 20 to 25 years, but the lifespan of wild counterparts is harder to determine. Based on field research in Ranomafana National Park and data from related sifaka species with similar ecological traits, individuals in the wild can live 18 to 20 years, with the oldest ever recorded being 32. However, fewer than 25% of wild Milne-Edwards’s sifakas survive beyond their first year due to predation, disease, and environmental pressures exacerbated by human activity.

Appearance

Cloaked in long and wooly dark brown to black fur, the robust Milne-Edwards’s sifaka is well-camouflaged in the dim understory of montane forests. Full sunlight rarely pierces through the dense, verdant treetops, so their fur helps absorb what little warmth filters down in the cool, damp air. Pale patches of beige or white occur on the limbs, thighs, and back, forming saddle-like patterns unique to individuals, and help identify them among Madagascar’s diverse lemur species. Infants are born with lighter, silverier coats that darken with age.

What truly commands attention, however, is their arresting orange-red gaze; they look as though startled by deep, uncomfortable thoughts. Though active during the day, Milne-Edwards’s sifakas have evolved huge, protruding eyes more typical of nocturnal creatures because of the forest’s perpetual twilight shade. With more light-sensitive rod cells than color-detecting cones, and a reflective tapetum lucidum behind each retina (which produces the “eye shine” effect), they see movement and depth that their anthropoid cousins would miss in the canopy.

Set like glowing embers against jet-black faces, their forward-facing eyes dramatically bulge from fluffy-framed heads topped with prominent round ears that can swivel independently. Their snout is tipped with a moist, dog-like rhinarium (wet nose), which grants them a superior sense of smell.

Their hands and feet are long, narrow, and extremely dexterous, with an opposable big toe and pseudo-opposable thumb for gripping branches and picking food. Like other lemurs, they also have a primitive grooming claw on the second toe of each foot. Most importantly, their bushy, serpentine tails act like a tightrope walker’s balance pole, keeping them stable as they move through their branch highways.

Males might have slightly broader chests and more obvious scent glands on their throats for marking territory, however, the two sexes otherwise look nearly identical.

Diet

Milne-Edwards’s sifakas are primarily folivorous (leaf-eaters) but exhibit dietary plasticity—a defining primate trait that refers to their ability to adapt their feeding habits to changes in the environment or resources. During Madagascar’s wet season, when the forest is lush and abundant, their diet is a smorgasbord of 35% seeds, 30% whole fruit, and 28% leaves. In the dry season, when food becomes more scarce, they switch to tougher fare like mature leaves, fungi, bark, and stems.

They are known to eat over 80 plant species in the mid-to-upper tree canopy, including members of the laurel (Lauraceae), mangosteen (Clusiaceae), and spurge (Euphorbiaceae) families. Many of these plants have fibrous leaves packed with defensive chemicals that most animals find inedible or even toxic. As hindgut fermenters, the Milne-Edwards’s sifakas’ digestion takes place in the large intestine rather than the stomach. There, symbiotic bacteria break down tough plant parts, though their specialized teeth do much of the work before the food even reaches the gut.

Their mouths are equipped with back teeth that have high, sharp cusps that act like industrial shredders, cutting and grinding coarse vegetation before swallowing. At the front of the jaw is a specialized “tooth comb” formed by elongated lower incisors. It’s mainly used for grooming, however, it can also scrape bark or clean plant surfaces before eating.

One of the more unusual aspects of their feeding behavior is geophagy, or soil-eating. Although this has been observed in many primates, it’s especially remarkable for the Milne-Edwards’ sifakas, who seldom come down to the forest floor. When they do descend, it’s usually brief and purposeful.

Their soil-eating isn’t random snacking. They seek out specific mineral-rich sites, sometimes traveling well beyond their normal territories to find them. When they arrive, just one to three individuals come down from the trees at a time to carefully collect a few mouthfuls of selected soil. All ages participate, but not without risk. While others feed, sentinel members keep watch, scanning for known lemur predators.

The consistency, intentionality, and associated risks of soil-eating suggest this behavior serves a crucial purpose, though scientists are still figuring out exactly what that purpose is. The leading theory is detoxification. Geophagy peaks during fruiting season (December–May), precisely when Milne-Edwards’ sifakas are gorging on their favorite seeds, which happen to contain alkaloids and other potentially harmful compounds. The clay-rich soils they choose seem to work like antacid tablets, binding to these toxins and helping expel them safely from their digestive tracts.

There’s also evidence that geophagy may help regulate gut acidity, a useful service for hindgut fermenters whose gut bacteria function best in neutral pH conditions.

Behavior and Lifestyle

Milne-Edwards’ sifakas are diurnal, meaning they are active during the day, with a fairly structured lifestyle. Maintaining defined territories of about 30 to 55 hectares (roughly 74 to 136 acres), they travel between 2,300 and 2,600 feet (700–800 m) each day. How time is budgeted depends heavily on the forest’s integrity and seasonal changes, though it follows a predictable pattern: foraging typically begins just after sunrise, followed by a midday rest period, then a second bout of foraging in the afternoon.

As they forage, individuals venture off, staying within visual and vocal proximity of other group members for safety. Dominant individuals get first access to food sites, and aggression is rarely observed in their groups. Adults seldom share food directly, nevertheless, infants may take food from their mothers or nearby males in an act of grown-up tolerance rather than intentional sharing.

In pristine, unlogged forests where the tree canopy forms a continuous highway, Milne-Edwards’s sifakas cover more ground in less time and devote more of it to feeding on a wider variety of preferred foods. Under these ideal conditions, they normally allocate their time to foraging (27%), traveling (7%), resting (44%), social behaviors (5–10%), and other activities.

Where heavy cutting has fragmented the forest, gaps in the canopy become too large for these specialized arborealists to cross, significantly reducing their mobility. Milne-Edwards’s sifakas living in these smaller, degraded territories experience higher stress levels due to food scarcity, increased competition, and the instability of their habitat. With fewer fruiting trees and edible leaves available, they’re forced to rely on lower-quality foods that are harder to find and less nutritious. To cope, they conserve what little energy they can extract, and that includes limiting their movement.

Even forests that have only been lightly logged alter their routines. Food is more dispersed, so they must travel farther than they would in undisturbed habitat because the canopy becomes patchier. It’s technically usable, but inefficient for the sifaka family’s signature style of locomotion, called vertical leaping and clinging (VCL).

Using only the strength of their elongated hind limbs, they ballistically launch their body from one vertical support to the next in athletic bounds of up to 20 feet (6m). The functional foundation of this lies in their body proportions: sifakas’ hind legs are significantly longer than their forelimbs. This tradeoff means they can’t pull themselves up or climb as well as other primates built for vertical scrambling, like monkeys or lorises.

For their infrequent ground visits, they don’t so much walk bipedally as hop bipedally. Acting as springs, their legs store energy and release it through propulsive push-offs, while their padded feet absorb landing impact. Since grasping branches isn’t needed during bipedal hopping, their arms are free to stabilize themselves as they keep their torsos upright. The odd elegance of their bounding is why sifakas are often compared to jeté-performing ballet dancers.

Fun Facts

The name “sifaka” is derived from the onomatopoeia of their alarm call “shi-fak.”

Milne-Edwards’s sifakas were once considered a subspecies of the diademed sifaka (P. diadema).

Females are dominant over males, which is rare among most simian primates, although not rare among lemurs

Daily Life and Group Dynamics

Lemurs commonly live in matriarchal groups where females outrank males, have priority access to food and preferred resting spots, and can displace males without resistance. Milne-Edwards’s sifakas exhibit an extreme form of this social system.

They lead highly social, calm, and cooperative lives in groups of three to nine individuals, though larger groups have been recorded. They usually consist of one or two breeding females, several males, and their offspring.

Their social structure is unusually flexible for a primate. Individuals immigrate or emigrate from groups based on local conditions, contrasting with the rigid hierarchies seen in species like baboons, macaques, or even the fission-fusion societies of chimpanzees (Pan troglodytes). The societies they form can assume multiple arrangements, including harems, multi-male/multi-female groups, male-female pairs, and single-female/multi-male groups.

This malleable social system probably developed as a result of the serious challenges posed by Madagascar’s environment. Apart from dealing with seasonal scarcity of food and a volatile ecosystem, Milne-Edwards’s sifakas are slow to mature and reproduce compared to many other animals. Being able to adapt group composition in response can mean the difference between surviving or not.

Neither sex establishes hard, demarcated ranks or hierarchies. Social roles are fluid and context-dependent. One female might take charge at a feeding spot while another leads the group to new areas. Male dominance is similarly situational and even more temporary than female relationships.

Serious aggression is incredibly rare among Milne-Edwards’s sifakas. Rather than fighting, they maintain their social order through non-physical means like vocalizations, body language, grooming, and scent marking. Conflicts that do escalate to physical violence or even death often occur between unrelated males competing during breeding season. Again, this is very rare in Milne-Edwards’s sifakas.

Females show remarkable social agency for mammals, actively choosing to leave groups with troublesome males or when they spot better feeding areas and breeding opportunities elsewhere. Males who stick around without gaining dominance often get shut out of mating by the alpha female, making dispersal the smarter reproductive strategy.

In Ranomafana National Park, sympatric neighbors include several other lemur species, such as red-bellied lemurs (Eulemur rubriventer), southern bamboo lemurs (Hapalemur meridionalis), and greater dwarf lemurs (Cheirogaleus major). These species occupy different layers of the forest canopy, feed at different times, or are in entirely different dietary niches. The spatial, temporal, and dietary separation helps everyone cohabitate. They aren’t social with one another, but they coexist like passing neighbors as opposed to active collaborators or competition.

Madagascar doesn’t have many predators capable of pursuing lemurs through the trees, but the agile fossa (Cryptoprocta ferox) is a notable exception. When a fossa is spotted, or even suspected, the group emits loud alarm calls and clusters tightly on the same tree or nearby branches. Infants cling to their mothers as evasive maneuvers are taken, each member leaping away in staggered bursts to avoid drawing attention to the entire group.

Raptors like the Madagascar harrier-hawk (Polyboroides radiatus) can prey on small juveniles, and Milne-Edwards’s sifakas can recognize these predators by silhouette alone. They may even react to the alarm calls of birds or other lemurs, demonstrating a kind of interspecies situational awareness, where they use cues from other animals to interpret a situation.

Communication

Lemurs communicate differently than most other primates, in part due to their natural history and the sensory challenges posed by Madagascar’s forest habitat. Strepsirrhines split from the primate lineage before the evolution of highly visual, social primates like monkeys and apes, whose primary senses are sight and sound. The Milne-Edwards’s sifaka and other lemurs, therefore, aren’t as reliant on visual cues and don’t use as many facial expressions to express themselves. They lean more on scent communication, as well as posture, social grooming, and to communicate with each other. 

Both sexes secrete a substance from their anal glands that they then rub onto a substrate, usually a branch, to mark it with their scent. Males also have a gland in the middle of their chests. People often simplify scent-marking to animal delineating to the world what belongs to them, however, chemical messaging is far more complex in Milne-Edwards’s sifaka. Of course, they do mark things to claim them. Females scent-mark to advertise their presence and mark their resources, clean-chested males use scent-marks as between-group communication to advertise their presence, and stained-chested males use scent-marks as a form of olfactory mate-guarding. 

The real drama unfolds in what’s called “overmarking”—when one sifaka starts deliberately graffitiing over another’s scent. Males respond to female scent-marking by overmarking with their own scent glands, usually by combining chest and genital marking. They also overmark other males, although less quickly and less often. All of this competitive marking culminates in “totem-trees,” which are trees that have so much scent on them that they become information hubs where all surrounding Milne’s-Edward’s sifaka learn who’s been where, when, and what their social status might be. Scent marks may even signal who’s related to whom.

Humid air muffles distant sounds, but Milnes-Edward’s sifakas still have a range of calls they use. Some calls are short-range, used to keep tabs on nearby individuals and coordinate movement. Others, like alarm barks or “tchi-faks,” are louder and more piercing, designed to cut through forest noise and warn the group of predators. They use submissive calls to defuse tension and resolve conflicts. Sometimes they make these peace-making sounds even before a fight breaks out, and other times they use them after an argument to smooth things over. 

Reproduction and Family

Unlike animals such as lizards that enter the world with fully instinctive behaviors, infant primates must develop survival skills through observation and experience from their families. This higher parental investment increases each offspring’s chances of reaching maturity in species with slow reproductive rates and long lifespans, such as the Milne-Edwards’s sifaka.

Females ovulate for just a few days during Madagascar’s January wet season, carefully timing births for when food is abundant for lactating mothers. If successful, a single infant is born after a 180-day gestation period in June or July, just as the forest enters its dry season. This precise timing ensures that mothers have access to adequate nutrition during the critical early months of infant development.

Baby Milne-Edwards’s sifakas are entirely dependent on their mothers for survival, clinging to her belly for the first few months of life. As they grow, they transition to her back and begin sampling leaves and fruits by six months, though they continue to nurse during rest and at night. Full weaning is completed by 18 months, but infants stay dependent on their mothers well into adolescence.

Fathers are tolerant of infants, but in no way assist with their care, even when they are part of the social group. There is no alloparenting in this species; biological mothers are their infants’ sole caregivers. 

The female reaches sexual maturity at around three to four years of age, while males become sexually mature slightly later, at around five to six years. This extended adolescence, along with high infant mortality rates (nearly 50% of infants die before reaching one year) and long intervals between births, puts immense pressure on each reproductive event.

Often referred to as the “ecological sex,” female Milne-Edwards’s sifakas are more sensitive to environmental stressors than males. If there’s social chaos or habitat disturbance, for example, she may skip a breeding season. Considering they have one offspring roughly every 22 months, a missed mating season has consequences that last for generations.

Despite their contracted mating window and being a polygynous species where one male can mate with multiple females, male competition for mates is surprisingly non-violent. Instead, it is chiefly a calculated social game. In their society, females largely control the terms of mating. Therefore, males don’t so much choose females as they position themselves to be chosen by her. During the breeding season, males will try to increase their chances by shadowing a dominant female, currying favor by grooming her. Others may decide they’ll fare better pursuing familiar, long-term resident females in stable groups or dispersing to find available mates in other troops.

If competition does erupt between two males, it is customarily mediated by vocalization, posturing, and countermarking to display dominance.

Civilized courtship breaks down when desperate bachelor males attempt hostile takeovers of established groups. An immigrant male, typically young or formally lower ranking, enters the territory of an occupant social group, systematically destroys resident males’ scent marks and vocalizes his arrival. If there are already adult males when he encounters the group, he may chase them or confront them. Sometimes the new male successfully evicts older or weaker members from the group. Other times, he may coexist with them temporarily, especially if the group is large or the females resist change.

If he successfully takes over the group, it “reshuffles,” resetting the social bonds, ranks, and lineages. Takeover males kill unweaned infants to bring females into estrus quicker, allowing them to produce offspring with resident females. Female infanticide appears to result in the emigration of the infant’s mother, enabling the immigrant female to become the new breeding female. Rather than risk this threat, pregnant females often abandon their groups entirely. This infanticide risk contributes to their dynamic group composition and high rates of group turnover.

Ecological Role

Madagascar was isolated from other landmasses for over 80 million years, and in that time, primates have come to fill niches that are typically held by different species on other continents. Compared to similar tropical ecosystems, the island has few fruit-eating birds and bats to disperse vital seeds that regenerate the lush plant life. Several lemur species have come to serve as ecological surrogates, excreting viable seeds from the fruit they eat.

While often labeled as a seed predator due to their tendency to masticate the majority of the seeds they consume, older Milne-Edwards’s sifakas, whose teeth have worn with age, are known to pass viable seeds intact. Because seeds and fruit constitute a large part of their diet, sifakas contribute to forest regeneration through seed dispersal in their excrement.

Because they rely on intact, undisturbed forest, the health of sifaka populations is a sensitive indicator of habitat quality. Their presence (or absence) can reveal how severely a forest has been degraded or how well it is recovering. By protecting Milne-Edwards’s sifakas and other forest primates, we also protect the rainforests that help store carbon and fight climate change. 

Conservation Status and Threats

The Milne-Edwards’s sifaka (Propithecus edwardsi) is classified as Endangered by the International Union for Conservation of Nature (IUCN, 2020), appearing on the IUCN Red List of Threatened Species. 

In the last 30 years, their populations have plummeted by more than 50%, driven predominantly by habitat degradation due to exploitative human activities, particularly slash-and-burn agriculture, illegal logging, gold mining, and climate change. Locally, lemurs are hunted by poachers and sometimes villagers for bush-meat, which not only reduces already vulnerable populations but disrupts group structure and social stability. For slow-reproducing species like Milne-Edwards’s sifaka, even small losses have long-term consequences.  

As strictly arboreal primates, Milne-Edwards’s sifakas cannot safely cross the roads, farms, and cleared land that now fragment their habitat. This pushes groups into isolated forest patches, preventing gene flow between populations and weakening their genetic diversity. Some long-term studies speculate that if deforestation keeps happening at its current rate, there’s a real chance these primates will go extinct by 2050.

Conservation Efforts

The Milne-Edwards’ sifaka is listed on 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.

The capture or sale of Milne-Edwards’ sifakas is internationally banned, and Madagascar’s laws ban hunting all lemur species. Yet protection on paper means little when enforcement crumbles under the weight of poverty and corruption. Mixed patrol brigades attempt to enforce these laws; however, bribery and scarce resources mean vast forest areas go unmonitored. 

Of roughly 28,600 Milne-Edwards’ sifakas remaining in the wild, fewer than 3,500 live within the supposed safety of protected areas. Ranomafana National Park, their primary sanctuary covering 41,500 hectares of montane rainforest, shelters approximately half the species’ total population, while Andringitra National Park provides additional but limited refuge.

The true threat to these primates emerges not from malice but from desperation: extreme poverty, malnutrition, and lack of alternatives. Impoverished communities practice slash-and-burn agriculture, clearing forest patches to grow rice and other crops in the nutrient-poor soil. They harvest trees for charcoal production, the primary cooking fuel across Madagascar, and collect precious hardwoods like rosewood for income. When these activities destroy sifaka habitat, and families still face hunger, hunting the displaced lemurs for protein becomes inevitable.

The most effective conservation programs address the root causes of why people choose survival over conservation. Dr. Patricia Wright, who helped establish Ranomafana National Park in 1991, leads the main conservation efforts through Centre ValBio, a world-class research facility that has monitored sifaka populations for over three decades. Her organization employs more than eighty local Malagasy and operates conservation programs across twenty-two villages, providing jobs as guides and researchers, mobile health clinics for remote areas, and reforestation projects that combine native tree planting with valuable crops like vanilla. 

Other organizations that provide additional support: the Duke Lemur Center offers research collaboration; USAID trains community rangers in monitoring techniques; and TRAFFIC tracks illegal wildlife seizures. These programs transform potential poachers into protectors by making conservation economically beneficial for local communities.

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Written by Alyssa Hanes, Jun 2025