Verreaux’s Sifaka, Propithecus verreauxi
VERREAUX'S SIFAKA
Propithecus verreauxi
Geographic Distribution and Habitat
Verreaux’s sifakas, like all lemurs, make their home in Madagascar and nowhere else in the world. They live in a wide range of diverse habitats over the southwestern and southern regions of the island. The habitats of these areas vary dramatically from dry spiny transitional forest patches to more humid rainforests. Verreaux’s sifakas have adapted to these diverse climates, varying from tropical to desert, and the types of vegetation these ecosystems produce.
Verreaux’s sifakas are members of the Indriidae family, also known as the “leaping lemur” family.
Size, Weight, and Lifespan
On average, from the crown of their head to their toes, Verreaux’s sifakas measure about 18 in (45 cm) long. Their tail is about the same length as the whole of their body. The length of their tail facilitates their incredible precision and balance as they leap from tree to tree.
They weigh between 7.5–7.9 lb (3.4–3.6 kg), with males on the higher end of the scale.
The accepted range for their lifespan is 18–23 years in captivity, and it is generally assumed that they do not live as long in the wild. However, one study found that they could live up to 31 years in the wild!
Appearance
With a hairless, dark face that’s offset with gold eyes, these lemurs have an alert and expressive gaze. They have white, soft fur that is thin around underarms, belly, and chest, showing their gray skin beneath. They have dark brown or reddish fur on the top and back of their head.
While the males and females look the same (they are not sexually dimorphic), there are differences in appearance between males. Some are “clean-chested” while others have a brown chest “stain” from a gland in their throat. (See more on this under Reproduction.) But to really appreciate the appearance of these lemurs, one must watch them travel.
Like other members of the Indriiae family, their arboreal (tree-dwelling) movements involve incredible quick and long vertical leaps from tree to tree. When they travel on the ground, they hold their arms up while their legs leap in a bipedal, two-legged, bound. They look like a child skipping with joy on their way to a play-date!
However delightful it is to see, this bipedal leaping action is how their locomotion adapted for the vast differences in their habitat—from leaping between tall treetops in tropical forests to traversing terrestrially (on the ground) across spiny transitional forest patches with no tree cover. Scientists who study their locomotion and its evolution disagree about whether it is an energy-efficient way to travel. Meanwhile, the appearance is as beautiful and transfixing as the best Broadway dance.
These leaping lemurs are herbivores (plant-eaters). Their diet corresponds to the season and climate. In the rainy season, when fruit and flowers are most plentiful, they consume the most food. Where it is dry, they eat mostly bark and leaves. Because of their need for a high caloric intake to preserve energy for their long vertical jumps from tree to tree and their bipedal skips across the ground (when they are not in motion) they prefer a sedentary lifestyle.
Sifakas are diurnal and in their waking hours, they mostly forage for food, groom, or sunbathe high up in the trees (where they also prefer to sleep). They love to warm their bellies, where they have less fur, in the sun.
They travel under half a mile to three-quarters of a mile a day (.8–1.2 km) depending on how enervating the travel is; they travel less when it is hot and dry. They travel in a group, called a troop, and they make sure to never leave anyone in their troop behind.
They leap from tree to tree with astounding speed, accuracy, and acrobatics. As they jump, their bodies rotate mid-air, so they can catch hold of a spiny, prickly tree—females do this with a baby holding onto them!
Sifakas have a toothcomb—a set of thin teeth in the front of their lower jaw that they use for grooming and peeling fruit. It can be useful for extracting nutrients from bark as well.
These lovely lemurs are very civilized: not only do they form social groups and cohesive societies, but they also value emotional intelligence. Females are often philopatric, staying within their birth group for life or returning to the place of their birth later in life. They use play tactics within their own troop and when meeting new sifakas. When there is aggression between them, they may later show acts of reconciliation—they are peace-makers.
Fun Facts
While the more common collective noun for sifakas is a troop, a group is also called a “conspiracy.” As in, “that conspiracy of sifakas inspires me to dance!”
Verreaux’s sifakas have partially webbed feet (the only lemur to have this!).
They don’t often use their hands to eat; instead they scoop food directly into their mouth with a “swoop” of their entire body.
Matriarchy, a social organization in which the power structure is based around the mother, is the social order for almost all of Madagascar’s lemurs, including Verreaux’s sifakas. The number in a troop can be anywhere between 2 and 13 individuals. A typical troop may have 5–7 females, 2 or 3 adult males, and babies.
Within their female-dominated social structure, each troop usually includes one dominant male and one or two subordinate males. The males can be aggressive during breeding season, especially against non-group males, but during the other seasons everyone works to get along. Regardless of the dominant-subordinate relationship between males, females are the apex of the hierarchy. Studies have found that where there is intersexual conflict, females are almost always the victor. While females have as much body mass as the males, physical dominance does not determine the outcome of conflict. The reproductive ability of a female is the basis of power within the troop.
Grooming is a very important activity for these sifakas. It is the way in which an established troop demonstrates their alliance with each other, and in fact they groom each other the most when there is another troop about.
Indeed, there is a friendly type of competition from troop to troop. At the same time that the in-group grooming is highest, they also engage in an effective tactic to lower aggression and xenophobia with outside troops: play. Like a “getting to know you” or “ice-breaker,” adults in the troops will use play/game tactics to become familiar with each other. Even during breeding season, in-group males engage in play with males outside their troop, and become, if not friends, more friendly. And where there has been conflict with males, both inside and outside the troop, they may make subsequent attempts at reconciliation.
There are clear benefits to cooperation: when everyone gets along they can all help in providing more coverage to alert the others to potential threats—safety in numbers!
The sifaka is named by the local Malagasy for a sound they make:“suh-fahk.” This bark is made to alert the troop to a threat, and is initiated by the troop leader. They may also growl, cluck, or make any number of variant calls to talk to each other.
As they have predators both from the ground and air, they must be highly alert. Even with their incredible leaping skills, they are still prey for harrier hawks and fossas. From the ground, they must beware of stray dogs and the most dangerous ape—the homo sapien. As they have different alarm calls to distinguish predators, “suf-fahk” may be their name for humans!
In addition to vocal communication, they also use scent marking. They have glands on their throat and genitals, and leave their personal perfume to linger behind as they move through the forest. Marking territory, asserting dominance, and advertising availability to breed—this type of scent-marking seems to be as varied as the expression of the individual sifaka. It’s a smelly type of social media.
Appearance, scent, and sexual activity meet in the color on the chest of some of the male sifakas. The brownish color on these males has to do with high testosterone levels in the gland on the throat that they use to scent-mark, and it “stains” their chests.
According to some studies, males with dark chests have higher testosterone levels than clean-chested males and they are typically the more dominant males. The males without the color on their chests release less scent and do less scent-marking. However, studies have shown that clean-chested males may offer more grooming to females, which is called a “grooming for sex” tactic, and may from time to time lead to breeding. One study found that the biggest scent releasers and most frequent groomers were the top breeders.
Breeding season is January through March and sifakas practice polygyny—males mate with multiple females. After breeding, the gestation period is 4 to 5 months and mothers have one baby. Babies are born between June and September, weighing less than 0.1 lb (40 gm). Mothers most often give birth during the dry season, meaning that they are not just feeding themselves but also their baby at a time when finding food is most challenging, so during this time they devote most of their time to foraging and eating.
Mothers carry their baby for about 6 months. A mother sifaka carries her infant on her chest or abdomen for the first 3 months of the baby’s life, and then carries her baby on her back for the next 2 or 3 months. She weans her baby at 6 months and then the baby can move more independently, but still will stick close by as he or she works toward independence. A sifaka does not reach their full adult size until 21 months. As a young sifaka grows in size and independence, they also build relationships within the troop. At 2.5 years of age, the sifaka becomes sexually mature. As the changes in the season begin, subordinate males may contest the dominant males in their or other troops. The individuals in a troop may change. New familial bonds may be formed between males and females as the cycle of birth begins again.
Verreaux’s sifakas, like all the lemurs of Madagascar, are integral and essential to the overall health of the island. As strict herbivores, they are vital seed dispersers to the varied forests and habitats in which they live and roam.
Verreaux’s sifaka is classified as Critically Endangered by the International Union for Conservation of Nature (IUCN, 2018), appearing on the IUCN Red List of Threatened Species.
Scientific studies on Verreaux’s sifaka are in no short supply, with calls for more. Their social dynamics, their bipedal locomotion, their scent markings, and many other behaviors make them the most studied of the Malagasy prosimians. Yet, in evaluating the research over the past 20 years, one reads a troubling tale between the lines. Twenty years ago, this species was listed as Vulnerable, and now it is one step away from extinction in the wild.
The greatest cause of the decline of the sifaka population continues to be rampant habitat loss. Slash-and-burn agricultural, over-logging, charcoal production, and commercial livestock has decimated the forests that many animals call home, including these charismatic lemurs. But there are other threats as well. Local tribes once considered the sifaka as sacred. While hunting sifakas is illegal, and for some tribes it is taboo, they are still killed for bushmeat. Feral dogs are also predators for these lemurs, as well as other endangered animals of the forest. The disease that killed the members of the Berenty Reserve is still not known or has not been publicly released. They are also victims of capture for the illegal pet trade.
Verreaux’s sifaka is listed on Appendix I of the Convention on International Trade in Endangered Species (CITES), which is a multilateral trade to protect endangered plants and animals.
There are a number of conservation groups whose mission is to educate people and help the endangered species of Madagascar, including a lemur action network. There are identified conservation sites, and at least one area where Verreaux’s sifaka are protected. Addressing the issue of feral dogs that prey on this species and others, there is a group working to spay/neuter and find homes for dogs where they can.
Another important consideration is the extreme poverty of many of the Malagasy people that drives the commercial loss of habitat. There are groups working within Madagascar to help build infrastructure for sustainable agriculture and fair wages. Global education and outreach is a priority. An equitable future for the local people will allow the Malagasy people to continue their heritage, which was to honor and protect these sacred sifakas of the forests.
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Written by Laura Lee Bahr, May 2020