Simpona, Silky simpona
The silky sifaka (Propithecus candidus ) is a large lemur characterized by long, silky, white fur. It has a very restricted range in northeastern Madagascar, where it is known locally as the simpona. It is one of the rarest mammals on Earth. The silky sifaka is one of nine sifaka species (genus Propithecus ), and one of four former subspecies of diademed sifaka (P. diadema ). Studies in 2004 and 2007 compared external proportions, genetics, and craniodental anatomy supporting full species status, which has generally been accepted.
The silky sifaka has a variable social structure, and lives in groups of two to nine individuals. It spends most of its day feeding and resting, though it also devotes a considerable amount of time to social behaviors, such as playing and grooming, as well as travelling. Females occasionally take priority over males during feeding. Like other eastern sifakas, it consumes mainly leaves and seeds, but also fruit, flowers, and even soil on occasion. It is a seasonal breeder and only mates one day a year during the start of the rainy season. As with other sifaka species, nonmaternal infant care is common. Group members of all ages and both sexes often groom, play with, occasionally carry, and even nurse infants that are not their own. The silky sifaka vocalizes frequently despite its moderately sized vocal repertoire consisting of seven adult calls. Like all other lemurs, it relies strongly on scent for communication. Males frequently scent-mark on top of scent marks made by other group members, particularly females. Males also gouge trees with their toothcomb (a special arrangement of the bottom, front teeth) prior to chest scent-marking. This chest marking results in males having brown-stained chests, the only visible trait that can be used to distinguish between adult males and adult females.
The species is only found within a few protected areas in the rainforests of northeastern Madagascar, with the majority of the remaining population in Marojejy National Park and Anjanaharibe-Sud Special Reserve. A few groups have also been found in the Makira Forest Protected Area, the Betaolana Corridor, and some unprotected forest fragments. The silky sifaka is hunted throughout its range as no local fady (taboo) exists against eating this species. Habitat disturbance, such as slash-and-burn agriculture (tavy ), illegal logging of precious woods (particularly rosewood) and fuel-wood, also occurs within the protected areas where it is found.
The Silky sifakas are unique, easily recognizable lemurs with a creamy white coat, due to which these animals are otherwise called 'angels of the forest’. Their coat is long, soft and silky, colored in white and tinged with silver on their back, legs and the head top. These lemurs exhibit furless, black faces as well as deep orange eyes. The lower back and the base of their tail are often darker and discolored. Mature males of this species are distinguished by the characteristic large, brown colored area on their chests. This is a result of their scent-marking habit, during which they use the special gland on the chest. Some individuals display pink areas on different parts of their body because of lacking skin pigment. The life expectancy of the population in the wild is currently unknown. Additionally, these animals cannot live in captivity, which doesn't allow to determine their lifespan. However, the closely related Verreaux's sifakas are known to live more than 23 years.
The Silky sifakas are endemic to Madagascar. The natural range of these animals covers a tiny area of the island, extending from Marojejy southwards to Makira and the Antainambalana River. However, the limits of their range are unknown. These lemurs are generally found in montane and mid-altitude rainforest habitat. Overall, they occur at high elevations, preferring a wide variety of habitats such as sclerophyllous forest or low ericoid bush, found at the highest elevations of their range.
The Silky sifakas live in a female-dominated society, forming groups of 2 - 9 individuals, consisting of one or more breeding pair, as well as smaller family units of an adult male and female with their young. Each group has its own territory, which can be up to 44 hectares in size. These groups are known to take daily trips of about 700 meters within their territory. The Silky sifakas are diurnal animals. The most of their active time is generally spent resting and looking for food. More precisely, 45% of the day is spent resting and up to 22% - foraging. Other important activities include grooming and playing as well as very short periods of moving. Usually, females tend to spend their time resting as much as possible, while males display more sociable behavior, moving around to participate in various activities. The Silky sifakas rest by bending their knees to hold them close to the abdomen and clinging to a vertical tree trunk.
As folivorous animals, the Silky sifakas generally consume mature and young leaves, seeds and fruits, supplementing this diet with occasional flowers, bark, and soil.
The reproductive system of this species is insufficiently explored. However, it is believed to largely depend on the social structure of a given community, since the Silky sifakas live in various units such as multi-male and/or multi-female groups, mixed groups or all-male groups. Hence, different groups of these lemurs may have either polygynous (each male has numerous mates) or monogamous (each individual has only one mate) reproductive systems. They are likely to have a very short mating period of a few days, occurring between November and January. Most births take place in June-July. Females usually give birth at intervals of 1 - 2 years. Gestation period lasts for 6 months, yielding a single infant, which will cling to the belly of its mother. Then, by 4 weeks old, the baby begins riding on the back of its mother. It will stay close to its mother, sleeping with her until becoming mature. Meanwhile, community members typically help the female to rear its offspring by carrying, nursing, grooming and playing with the infant.
One of the biggest threats to the population of these animals is habitat disturbance and destruction. Another serious concern is hunting, compounded by the absence of any local taboo (or fady) against hunting and consuming Silky sifakas. Moreover, these lemurs are commonly hunted even within the protected areas of Marojejy National Park and the Anjanaharibe-Sud Special Reserve.
According to the IUCN Red List, the total population of Silky sifakas is less than 250 mature individuals. Currently, this species is classified as Critically Endangered (CR) and its numbers continue to decrease.
The ecological niche of this species is unclear. However, the silky sifakas probably act as important seed dispersers of their range due to their folivorous diet. Additionally, they are hunted and consumed by humans and fossas.