Critically Endangered (IUCN Red List, 2019)
What they look like
The pelage is long, silky and white, which gives this species its common name. In some individuals, silver-gray or black tints may appear on the crown, back and limbs, and the pygal region (at the base of the tail) is sometimes yellow. The muzzle and face are bare, and tips of the naked black ears protrude just beyond the white fur of the head and cheeks.
Although all infants are born with black skin, all individuals lose pigmentation to varying degrees as they get older, resulting in skin color which is a mix of pink and black, with some individuals having all pink or all black faces. Adult males and females can be readily distinguished from one another by the pelage coloration of the upper chest. Adult males have a large brown “chest patch” that results from chest scent-marking with the sternal gular gland.
Where they live
The silky sifaka has a restricted range in the mountainous rainforests of northeastern Madagascar with most of the remaining population found inside Marojejy National Park and Anjanaharibe-Sud Special Reserve. The Makira Natural Park and COMATSA-Sud Protected Area also contain some groups as well as the unprotected Maherivaratra forest. They prefer higher elevations and are seldom found below 650 meters of altitude.
What they eat
They are folivorous seed-predators that eat primarily leaves and seeds but also considerable amounts of fruits and flowers and occasionally soil. More than 100 types of trees, vines, and epiphytes are eaten.
How they behave
They are arboreal spending almost all their time in the trees and only active during the day (diurnal). They travel by vertical clinging and leaping which allows them to leap more than 20 feet between tree trunks.
Group sizes range from two to nine individuals. Social structure is variable. Small groups are pair bonded family groups while some larger groups are polygynous containing more than one breeding female though never more than one adult male.
Approximately 25% of the day is spent feeding, 44% resting, and the remainder is devoted to social behavior (16.8%), travelling, and sleeping. Long bouts of terrestrial play involving adults are not uncommon. Rates of aggression are low, and occur mainly during feeding. Females have feeding priority over males.
How they reproduce
Mating occurs on a single day each year in December or January. Infants are born in June or July. Females generally give birth to a single offspring every two years, although births in consecutive years have been observed. Infants initially grasp the fur on their mother’s belly, and only about four weeks later begin to ride “jockey style” on their mothers back. All group members interact affiliatively with infants. Grooming is the most frequent form of non-maternal infant care, followed by playing, occasional carrying, as well as nursing in a few remarkable instances.
What threats they face
Silky sifakas are hunted throughout their range as there is no local taboo against eating them. Habitat disturbance is occurring in and around their habitat primarily from slash-and-burn or swidden agriculture for rice as well as selective logging for precious wood (rosewood, ebony) and other hardwoods for home construction. Artisanal mining for quartz and amethyst as well as vanilla plantations are also a concern. The fossa is their primary natural predator.
Silky Sifakas in Marojejy National Park and Anjanaharibe-Sud Special Reserve
This species is easiest to observe at Camp Marojejia (Camp 2) in Marojejy National Park and at Camp Indri in Anjanaharibe-Sud Special Reserve.