Silky Sifaka
Encyclopedia
The silky sifaka or silky simpona, 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, and is listed by the International Union for Conservation of Nature (IUCN) as one of the world's 25 most critically endangered primates
. 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 cranio-dental 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 traveling. 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, non-maternal infant care is common. Group members of all ages and both sexes will often groom, play, 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 lemurs, it relies strongly on scent
for communication. Males will 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 there is no local taboo (fady) 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.
given by western dry forest sifakas in which they emit an explosive, hiss-like "shee-faak" call several times in succession. On the east coast, local residents refer to the larger bodied diademed sifaka
as simpona, a name which refers to the species' sneeze-like "zzuss" alarm vocalizations. The calls are emitted in a variety of stressful circumstances such as presence of humans, falling trees, terrestrial predators, and after aggression between group members. The species name, candidus, is Latin for "white", while the species name of the taxonomic synonym
sericeus is derived from the Greek word for "silk".
in a formally published letter to French zoologist Alphonse Milne-Edwards
. Grandidier's description was based on his own observations north of the Bay of Antongil in the last few months of 1870. He then named the species Propithecus candidus due to its white color, which he likened to that of the Verreaux's sifaka
(Propithecus verreauxi), but without the dark fur on its head or the ash-colored spot on the back. The first specimen was obtained in 1872 and provided by "Monsieur Guinet", a planter from Sambava
. The specimen allowed both Grandidier and Milne-Edwards to more thoroughly describe the species based on its skin, coat
, and skull. Upon those findings, they changed the name to P. sericeus. Upon further review in 1875, Grandidier demoted the silky sifaka to a variety or "race" of the diademed sifaka. By the time German zoologist Ernst Schwarz
standardized lemur taxonomy
in 1931, P. sericeus had become a taxonomic synonym for the species, with the original name, Propithecus candidus, taking priority
.
Schwarz placed all sifakas into two species, the larger diademed sifaka from the eastern rainforests
and the smaller Verreaux's sifaka from the dry forests
and spiny forests
of the west and south. At the time, both species comprised four subspecies
, and the silky sifaka was listed as P. diadema candidus, a subspecies of the diademed sifaka. In his 1982 book Primates of Madagascar, anthropologist Ian Tattersall
upheld this classification. When anthropologist Colin Groves
reviewed the taxonomy in his book Primate Taxonomy in 2001, he also upheld the subspecies status of the silky sifaka because variations in fur coloration between the available specimens suggested converging similarities with the diademed sifaka's coloration. Groves later noted that the coloration of the two species did not overlap, suggesting that the populations were distinct.
In 2004, Mayor
et al. showed that despite having a similar karyotype
(the number and appearance of chromosome
s) of 42 chromosomes (2n=42), the silky sifaka was distinct from the diademed sifaka. This was shown through genetic tests (D-loop
sequencing) and by comparing external proportions. For example, the silky sifaka has a shorter tail. Their analysis indicated a closer relationship with Perrier's sifaka
(Propithecus perrieri). Russell Mittermeier
and colleagues followed by adopting the full species status of the silky sifaka for the 2nd edition of Lemurs of Madagascar
in 2006. Although Groves maintained the silky sifaka as a subspecies in the 3rd edition of Mammal Species of the World
in 2005, he recognized it as a distinct species in 2007 by acknowledging the work of Mayor et al. and also noting the additional distinction that the silky sifaka has relatively long molar teeth
compared to the length of its toothrow. Despite the promotion to full species status, the silky sifaka is still considered to be a member of the P. diadema group, a group of four closely related, large-bodied, eastern rainforest sifakas. The other three members of this group are the diademed sifaka, Perrier's sifaka, and Milne-Edwards' sifaka
(Propithecus edwardsi). The species status of the silky sifaka, as well as other sifakas, does not have universal support: in 2007, Tattersall argued against species distinctions within Propithecus, claiming the decisions were made prematurely.
In 1974, Tattersall spotted what he thought was a color variant of the silky sifaka north of Vohemar
in northeast Madagascar. Describing it as such eight years later in The Primates of Madagascar, he not only cited its mostly white fur, but also uncharacteristic traits such as a patch of orange on its crown and tufted ears. It was not observed again until 1986, when a team led by paleoanthropologist Elwyn Simons captured specimens for captive breeding
and identified it as a new species, named as the golden-crowned sifaka
(Propithecus tattersalli) in 1988.
in the south to the Andapa Basin and the Marojejy Massif in the north. Marojejy National Park
represents the northern limit of its current distribution, although historical sifaka range maps created by Grandidier and Milne-Edwards in the late 19th century show the silky sifaka as far north as the Bemarivo River
, north of Sambava
. The Androranga River may represent the northwestern range limit within the Tsaratanana Corridor. The southern limit of its range appears to be the Antainambalana River, within the Makira Conservation Site. It is not known if the silky sifaka has ever ranged as far south as the Masoala Peninsula. As of 2009, new observations of a few groups of the silky sifaka in unprotected forest fragments adjacent to northeastern Makira (Antohaka Lava and Maherivaratra
) may slightly enlarge the known geographic range of this species. The presence of the silky sifaka has been documented within Marojejy National Park, Anjanaharibe-Sud Special Reserve
, the Makira Forest Protected Area
, the Betaolana Corridor, and the Tsaratanana Corridor. In 2008, 16 groups were discovered in western Marojejy near Antsahaberoaka.
The silky sifaka tends to be found at higher elevations than any of the other sifaka species and also occupies the greatest range of elevations for the group. In Marojejy National Park and Anjanaharibe-Sud Special Reserve, where most of the remaining groups exist, it is not found below 700 m (2,296.6 ft) of elevation and not above 1875 m (6,151.6 ft). However, at its southernmost location in Makira (Andaparaty), several groups inhabit forest fragments at an unusually low elevation of 300 m (984.3 ft). The silky sifaka inhabits three types of elevation-specific habitats: primary montane rainforest
, sclerophyllous forest
, and the most elevated portions of low ericoid bush
. It is unknown how sensitive the silky sifaka is to disturbance or whether it avoids habitat edges ("edge-intolerant") or is more edge-tolerant like the diademed sifaka. Like other rainforest sifaka species, it seldom crosses non-forested regions between forest fragments.
In the Anjanaharibe-Sud Special Reserve, the silky sifaka is sympatric (shares the same geographic range) with the white-fronted brown lemur (Eulemur albifrons) and an all-black population of indri
(Indri indri). In Marojejy National Park, it is sympatric with the white-fronted brown lemur. In 2008, it was suggested that the silky sifaka may be sympatric with the red ruffed lemur
(Varecia rubra) near Maherivaratra and Andaparaty.
has a silky texture. Not all individuals are completely white: some have silver-gray or black tints on the crown, back, and limbs. The base of the tail ("pygal region") can be yellow. The ears and face are hairless, and the skin may be a mix of pink and black, completely black, or completely pink. The tips of the ears protrude slightly above the fur on the rest of the head. Its eyes have a deep orange-red coloration. Its appearance is distinctive, and since no other sifakas share its range, it is not easily confused with other lemur species.
While it is difficult to distinguish adult males and females in other eastern rainforest sifakas, such as the Perrier's sifaka and Milne-Edwards' sifaka, gender in the silky sifaka is easily discerned due to differences in fur coloration of the upper chest. Females have white fur, while males have a large brown patch of fur that results from scent marking
with a gland on the chest and throat (the sternal gular gland). During mating season, the size of the "chest patch" increases to cover both the chest and abdomen as a result of increased scent marking.
, one-male group
s, and multi-male/multi-female groups
. Group sizes range from two to nine individuals, while the home range
s are estimated to range from 34 to 47 ha (0.131274733921462 to 0.181468014538491 sqmi), varying in size by location.
According to some studies, the silky sifaka spends most of its day resting and feeding (approximately 44.4% and 25% respectively). It also devotes approximately 16.8% of the day to social behavior, such as personal grooming
, social grooming
(allogrooming), and play. The rest of the day is spent traveling and sleeping. Other sources report that the species divides half of the day between traveling and foraging, while the rest is spent resting. Daily foraging usually starts at dawn unless delayed by rain. Group movement is usually led by females, and groups usually travel 700 m (2,296.6 ft) per day, and may climb 500 m (1,640.4 ft) along vertical slopes. Although the species spends its time in the trees, terrestrial play is not uncommon, even among adults, with play sessions lasting 30 minutes or more. Like other sifakas, it uses a type of arboreal locomotion
known as vertical clinging and leaping
. Dominance hierarchies
have not been documented among female sifakas, including the silky sifaka, although seasonal hierarchies are known to occur. Aggression
, which is generally infrequent, occurs primarily during feeding, where females take priority over males, although submissive signals are not always obvious.
The silky sifaka's diet is similar to that of other eastern rainforest sifakas, consisting primarily of leaves (folivory
) and seeds (seed predation
). It is highly varied and includes many plant species. A two-month study from the mid-2000s showed that the silky sifaka can feed on as many as 76 species of plant from 42 families
. Its favorites included primarily tree species, but also some liana
s. The most prominent plant families in the diet were Moraceae
(20.30%), Fabaceae
(12.87%), Myrtaceae
(12.65%), Clusiaceae
(10.13%) and Apocynaceae
(9.49%). In the study, feeding upon these four plant families took up as much as 37.06% of the total feeding time for the silky sifaka: 16.09% on the fruit of Pachytrophe dimepate, 8.43% on the seeds of Senna
sp., 6.52% on the young leaves of Plectaneia thouarsii, and 6.02% on the fruit of Eugenia
sp. In sum, folivory accounted for 52% of the feeding time, while frugivory
(fruit-eating) accounted for 34%, and seed predation made up 11%. The consumption of flowers, as well as soil (geophagy
), was rarely observed in this study. Prior to this, preliminary studies had reported that folivory account for 75% of the diet, while fruits and 15% was seed predation, 7% was flower consumption, and bark and soil made up the remainder.
Like all other lemurs, the silky sifaka is a seasonal breeder
, and it is thought that it mates
only one day a year during the start of the rainy season sometime in December or January. Infants are born six months later in June or July. Females typically give birth to a single infant once every two years, although births in consecutive years have been observed. Infants initially cling to the fur of their mother's chest for nearly four weeks and then switch to riding on her back. As with other eastern rainforest sifakas, the infants of this species develop rapidly. This may be due to assistance in the care of infants by all group members (known as alloparental care)—a trait typical among all sifakas. Non-maternal care usually takes the form of allogrooming, but also playing, occasional carrying, and in rare cases, nursing. The dispersal of offspring is thought to be similar to that of other eastern rainforest sifakas, with both males and females transferring out of the group at sexual maturity
. However, dispersal has only been observed once with a young adult male, who left its natal group and proceeded to oust an older male from a group in which he had been a member for seven years. Female dispersal and group transfer has not yet been observed.
The only documented predator of the silky sifaka, other than humans, is the fossa
, a cat-like carnivore
found only on Madagascar. Although no aerial predators are known, the silky sifaka often watch the sky and emit loud "aerial disturbance" roars at the sight of the large Madagascar buzzard
(Buteo brachypterus) and other small birds. Another more general alarm call is the loud, sneeze-like "zzuss" vocalization
, which are emitted in response to terrestrial disturbances, calls from lost group members, and aggression by other group members. Acoustic analyses of the "zzuss" vocalization have shown that the call's acoustic
structure differs between individuals and by gender.
Adult eastern sifakas have a moderately sized vocal repertoire of about seven call types. It is uncertain if their vocalizations have specific or varied contexts, and as with other primates, arousal level may play a role in the acoustic structure of its calls. Despite the limited size of the silky sifaka's vocal repertoire, it does exhibit high call rates of seven calls per hour, on average. Even infants are known to have several specialized vocalizations. The most frequently emitted silky sifaka vocalizations are low-amplitude, low-frequency, tonal "hum" and "mum" vocalizations. These contact calls are used in a variety of circumstances including group movement, affiliation, foraging, and while resting.
The silky sifaka uses well-developed olfactory
(smell-based) communication, as with all other prosimian
("pre-monkey") primates. Like other eastern rainforest sifakas, it has several specialized glands for scent-marking
, including a sebaceous gland
on the chest, found only in males, and mixed apocrine-sebaceous glands on the genitals
in both sexes. Unlike the true lemurs of the genus Eulemur, the silky sifaka does not directly scent-mark its conspecifics (allomarking), although it does scent-mark its territory. Both sexes will often urinate while scent-marking. Males and females scent-mark in different ways: females rub their genital glands in an up-and-down motion against trees, while males may use their chest gland, genital glands, or a combination of both. Males will also use their specialized prosimian toothcomb
to gouge trees before scent-marking with their chest—a behavior that leaves long-lasting visible marks. The gouging is thought to serve a role in communication and has no dietary component, since males do not eat the bark or tree gum.
Males scent-mark more frequently than females, as much as two or three times as often. Males also respond to female scent-marking by overmarking with their own scent glands, usually by combining chest and genital marking. They will also overmark other males, although less quickly and less often. In a one-year study, males responded to 71% of the marks made by females within an average of 61 seconds while only 17% of male marks received a response from other group members. Because males overmark frequently, this results in "totem-tree marking", where certain trees become covered by male scent and gouge marks. However, no observations of widespread home range border scent-marking have been reported. Scent-marks are usually left on trees in the core area of the home range, as opposed to the territorial boundaries.
According to the most recent IUCN Red List assessment, the silky sifaka is Critically Endangered
. It is one of the rarest and most critically endangered lemurs. The silky sifaka is one of five lemurs listed as one of "The World's 25 Most Endangered Primates
" and has been on the list all five times since its inception in 2000. Its population size is estimated to range between 100 and 1,000 individuals, while the number of mature individuals is thought to be less than 250. There are no silky sifakas in captivity, such as in zoos.
The silky sifaka is the flag-ship species
for the protected areas in which it is found, particularly for Marojejy, which has recently been inaugurated as part of a World Heritage Site
cluster known as the Rainforests of the Atsinanana
. Habitat disturbance, such as slash-and-burn agriculture
(known locally as tavy), logging of precious woods (e.g., rosewood
) and fuel-wood, also occurs within the protected areas where it is found. Unlike the golden-crowned sifaka
(Propithecus tattersalli), there is no local taboo (fady) against eating this species, and the hunting of bushmeat
is a known issue within its range. It is most heavily hunted in the northern and western parts of Marojejy, as well as other areas around the Andapa Basin. The species is restricted to 90000 ha (347.5 sq mi) of protected areas, although this may be an overestimation because in much of its range the silky sifaka is not found below 700 m (2,296.6 ft) in altitude, possibly due to either hunting pressure or habitat preference.
Illegal logging
of precious hardwoods, such as rosewood and ebony
, has become one of the greatest threats to the silky sifaka's habitat, especially since the 2009 Malagasy political crisis. Its two largest protected areas, Masoala National Park and Marojejy National Park, have been the hardest hit. The disturbance caused by selective logging increases the likelihood of forest fires, helps invasive species
take root, impairs habitat, and causes the loss of genetic diversity
.
Local villages adjacent to its remaining protected areas adopted a two-pronged strategy towards silky sifaka conservation education. First, a "cognitive component" was implemented to increase knowledge and awareness through radio interviews, slide presentations, and the disbursement of literature in twelve primary and secondary schools. Additionally, an "emotional component" was begun to link silky sifaka conservation with positive emotional experiences, with the goal of establishing a psychological connection between the children and the lemur. To do this, groups of children were taken on three-day educational eco-tours
in Marojejy National Park. Both the teachers and the students showed interest and genuine concern about the plight of the silky sifaka.
Plans are being made to both expand Anjanaharibe-Sud Special Reserve and link existing parks and reserves in the region with wildlife corridors
. These corridors include the Betaolana Corridor between Marojejy and Anjananharibe-Sud and Makira, which will connect Anjananharibe-Sud with Masoala National Park
to the south. In addition to providing additional habitat for the silky sifaka, the corridors would promote genetic exchange between currently isolated populations.
Lemur
Lemurs are a clade of strepsirrhine primates endemic to the island of Madagascar. They are named after the lemures of Roman mythology due to the ghostly vocalizations, reflective eyes, and the nocturnal habits of some species...
characterized by long, silky white fur. It has a very restricted range in northeastern Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
, where it is known locally as the simpona. It is one of the rarest mammals on earth, and is listed by the International Union for Conservation of Nature (IUCN) as one of the world's 25 most critically endangered primates
The World's 25 Most Endangered Primates
The World's 25 Most Endangered Primates is a list of highly endangered primate species selected and published by the International Union for Conservation of Nature Species Survival Commission Primate Specialist Group , the International Primatological Society , and Conservation International...
. The silky sifaka is one of nine sifaka
Sifaka
Sifakas are a genus of lemur from the family Indriidae within the order Primates. Their name of the family is an onomatopoeia of their characteristic "shi-fak" alarm call. Like all lemurs, they are found only on the island of Madagascar...
species (genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Propithecus), and one of four former subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of diademed sifaka
Diademed Sifaka
The diademed sifaka , or diademed simpona, is an endangered species of sifaka, one of the lemurs endemic to certain rainforests in eastern Madagascar. This species is one of the world's largest living lemurs, with a total adult length of approximately 105 centimetres , half of which is tail...
(P. diadema). Studies in 2004 and 2007 compared external proportions, genetics, and cranio-dental 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 traveling. 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
Seasonal breeder
Seasonal breeders are animal species that successfully mate only during certain times of the year. These times of year allow for the births at a time optimal for the survival of the young in terms of factors such as temperature, food and water. Related sexual interest and behaviors are expressed...
and only mates one day a year during the start of the rainy season. As with other sifaka species, non-maternal infant care is common. Group members of all ages and both sexes will often groom, play, 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 lemurs, it relies strongly on scent
Olfaction
Olfaction is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates...
for communication. Males will frequently scent-mark
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
on top of scent-marks made by other group members, particularly females. Males also gouge trees with their toothcomb
Toothcomb
A toothcomb is an anatomical structure found in strepsirrhine primates, which includes lemurs, lorises and galagos. A toothcomb consists of long, flat forward-angled teeth, and includes the lower incisors and the canine teeth...
(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
Marojejy National Park
Marojejy National Park is a national park in the Sava Region of northeastern Madagascar. It covers and is centered around the Marojejy Massif, a mountain chain that rises to an elevation of . Access to the area around the massif was restricted to research scientists when the site was set aside as...
and Anjanaharibe-Sud Special Reserve
Anjanaharibe-Sud Reserve
Anjanaharibe-Sud Reserve is a wildlife reserve of Madagascar. It was nominated to the UNESCO Tentative List of World Heritage Sites in Madagascar in 2008 as an extension to the Rainforests of the Atsinanana....
. A few groups have also been found in the Makira Forest Protected Area
Makira Natural Park
The Makira Natural Park will be one of Madagascar's largest protected areas, and one of the first to be created under the president's "Durban Vision", which aims to triple the area under protection during the period 2003-2008...
, the Betaolana Corridor, and some unprotected forest fragments. The silky sifaka is hunted throughout its range as there is no local taboo (fady) against eating this species. Habitat disturbance, such as slash-and-burn agriculture
Slash and burn
Slash-and-burn is an agricultural technique which involves cutting and burning of forests or woodlands to create fields. It is subsistence agriculture that typically uses little technology or other tools. It is typically part of shifting cultivation agriculture, and of transhumance livestock...
(tavy), illegal logging of precious woods
Illegal logging in Madagascar
Illegal logging has been a problem in Madagascar for decades and is perpetuated by extreme poverty and government corruption. Often taking the form of selective logging, the trade has been driven by high international demand for expensive, fine-grained lumber such as rosewood and ebony...
(particularly, rosewood
Rosewood
Rosewood refers to any of a number of richly hued timbers, often brownish with darker veining, but found in many different hues. All rosewoods are strong and heavy, taking an excellent polish, being suitable for guitars, marimbas, turnery , handles, furniture, luxury flooring, etc.In general,...
) and fuel-wood, also occurs within the protected areas where it is found.
Etymology
The name "sifaka" is a reference to a common general alarm vocalizationAnimal communication
Animal communication is any behavior on the part of one animal that has an effect on the current or future behaviour of another animal. The study of animal communication, is sometimes called Zoosemiotics has played an important part in the...
given by western dry forest sifakas in which they emit an explosive, hiss-like "shee-faak" call several times in succession. On the east coast, local residents refer to the larger bodied diademed sifaka
Diademed Sifaka
The diademed sifaka , or diademed simpona, is an endangered species of sifaka, one of the lemurs endemic to certain rainforests in eastern Madagascar. This species is one of the world's largest living lemurs, with a total adult length of approximately 105 centimetres , half of which is tail...
as simpona, a name which refers to the species' sneeze-like "zzuss" alarm vocalizations. The calls are emitted in a variety of stressful circumstances such as presence of humans, falling trees, terrestrial predators, and after aggression between group members. The species name, candidus, is Latin for "white", while the species name of the taxonomic synonym
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
sericeus is derived from the Greek word for "silk".
Taxonomy
The silky sifaka was initially described in 1871 by French naturalist Alfred GrandidierAlfred Grandidier
Alfred Grandidier was a French naturalist and explorer.From a very wealthy family, he and his brother, Ernest Grandidier , undertook a voyage around the world...
in a formally published letter to French zoologist Alphonse Milne-Edwards
Alphonse Milne-Edwards
Alphonse Milne-Edwards was a French mammalologist, ornithologist and carcinologist. He was English in origin, the son of Henri Milne-Edwards and grandson of Bryan Edwards, a Jamaican planter who settled at Bruges .Milne-Edwards obtained a medical degree in 1859 and became assistant to his father...
. Grandidier's description was based on his own observations north of the Bay of Antongil in the last few months of 1870. He then named the species Propithecus candidus due to its white color, which he likened to that of the Verreaux's sifaka
Verreaux's Sifaka
Verreaux's sifaka , or white sifaka, is a medium sized primate in one of the lemur families, Indriidae. It lives in Madagascar and can be found in a variety of habitats from rainforest to western Madagascar dry deciduous forests and dry and spiny forests...
(Propithecus verreauxi), but without the dark fur on its head or the ash-colored spot on the back. The first specimen was obtained in 1872 and provided by "Monsieur Guinet", a planter from Sambava
Sambava
Sambava is a city and commune at the east coast of northern Madagascar. It is the capital of Sambava District and Sava Region. The population of the commune was estimated to be approximately 40,000 in 2001 commune census....
. The specimen allowed both Grandidier and Milne-Edwards to more thoroughly describe the species based on its skin, coat
Fur
Fur is a synonym for hair, used more in reference to non-human animals, usually mammals; particularly those with extensives body hair coverage. The term is sometimes used to refer to the body hair of an animal as a complete coat, also known as the "pelage". Fur is also used to refer to animal...
, and skull. Upon those findings, they changed the name to P. sericeus. Upon further review in 1875, Grandidier demoted the silky sifaka to a variety or "race" of the diademed sifaka. By the time German zoologist Ernst Schwarz
Ernst Schwarz
Ernst Schwarz was a German zoologist.Schwarz was born in Frankfurt and studied zoology in Munich. He worked at the Museum of Natural History in Frankfurt and the Zoological Museum in Berlin. In 1929 he became professor of Zoology at the University of Greifswald. He worked at the Natural History...
standardized lemur taxonomy
Taxonomy of lemurs
The taxonomic history of lemurs dates back to 1758 when Carl Linnaeus first classified them, and the taxonomy remains controversial today, with approximately 70 to 100 species and subspecies recognized, depending on how the term "species" is defined...
in 1931, P. sericeus had become a taxonomic synonym for the species, with the original name, Propithecus candidus, taking priority
Principle of Priority
thumb|270px|Boa manditraIn zoology, the scientific study of animals, the Principle of Priority is one of the guiding principles of the International Code of Zoological Nomenclature, defined by Article 23....
.
Madagascar lowland forests
The Madagascar lowland forests are a tropical moist broadleaf forest ecoregion, found on the eastern coast of the island of Madagascar.-Setting:...
and the smaller Verreaux's sifaka from the dry forests
Madagascar dry deciduous forests
The Madagascar dry deciduous forests represent a tropical dry forest ecoregion generally situated in the western part of Madagascar. The area has high numbers of endemic plant and animal species but has suffered large-scale clearance for agriculture...
and spiny forests
Madagascar spiny thickets
The Madagascar spiny thickets is an ecoregion in Madagascar. The vegetation type is found on poor substrates with low, erratic winter rainfall. An estimated 14,000 to is covered with this habitat, all in the southwest of the country...
of the west and south. At the time, both species comprised four subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
, and the silky sifaka was listed as P. diadema candidus, a subspecies of the diademed sifaka. In his 1982 book Primates of Madagascar, anthropologist Ian Tattersall
Ian Tattersall
Ian Tattersall is a paleoanthropologist and a curator at the American Museum of Natural History. Tattersall received his PhD from Yale University in 1971. In addition to human evolution, he has worked extensively with lemurs. He is working with The Templeton Foundation.-Selected publications:* The...
upheld this classification. When anthropologist Colin Groves
Colin Groves
Colin Peter Groves is Professor of Biological Anthropology at the Australian National University in Canberra, Australia.Born in England on 24 June 1942, Colin Groves completed a Bachelor of Science at University College London in 1963, and a Doctor of Philosophy at the Royal Free Hospital School of...
reviewed the taxonomy in his book Primate Taxonomy in 2001, he also upheld the subspecies status of the silky sifaka because variations in fur coloration between the available specimens suggested converging similarities with the diademed sifaka's coloration. Groves later noted that the coloration of the two species did not overlap, suggesting that the populations were distinct.
In 2004, Mayor
Mireya Mayor
Mireya Mayor is a wildlife correspondent for the National Geographic. She is also a former cheerleader for the NFL's Miami Dolphins. She was a Fulbright Scholar before earning a PhD in anthropology from Stony Brook University in New York....
et al. showed that despite having a similar karyotype
Karyotype
A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism.p28...
(the number and appearance of chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
s) of 42 chromosomes (2n=42), the silky sifaka was distinct from the diademed sifaka. This was shown through genetic tests (D-loop
D-loop
In molecular biology, a displacement loop or D-loop is a DNA structure where the two strands of a double-stranded DNA molecule are separated for a stretch and held apart by a third strand of DNA. The third strand has a base sequence which is complementary to one of the main strands and pairs with...
sequencing) and by comparing external proportions. For example, the silky sifaka has a shorter tail. Their analysis indicated a closer relationship with Perrier's sifaka
Perrier's Sifaka
Perrier's sifaka is a sifaka endemic to Madagascar. It has a length of 85 to 92 centimeters, of which 42-46 centimeters are tail. Perrier's sifaka has a very limited range in northeastern Madagascar between the Irodo River to the north and the Lokia River to the south. It lives in dry deciduous...
(Propithecus perrieri). Russell Mittermeier
Russell Mittermeier
Russell Alan Mittermeier is a primatologist, herpetologist and biological anthropologist. He has written several books for both popular and scientist audiences, and has authored some 300 scientific papers.-Biography:...
and colleagues followed by adopting the full species status of the silky sifaka for the 2nd edition of Lemurs of Madagascar
Lemurs of Madagascar (book)
Lemurs of Madagascar, currently in its third edition, is a reference work and field guide for the lemurs of Madagascar, giving descriptions and biogeographic data for the known species. The primary contributor is Russell Mittermeier, president of Conservation International, and the cover art and...
in 2006. Although Groves maintained the silky sifaka as a subspecies in the 3rd edition of Mammal Species of the World
Mammal Species of the World
Mammal Species of the World, now in its 3rd edition, is a standard reference work in zoology giving descriptions and bibliographic data for the known species of mammals.An updated Third Edition of Mammal Species of the World was published late in 2005:...
in 2005, he recognized it as a distinct species in 2007 by acknowledging the work of Mayor et al. and also noting the additional distinction that the silky sifaka has relatively long molar teeth
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
compared to the length of its toothrow. Despite the promotion to full species status, the silky sifaka is still considered to be a member of the P. diadema group, a group of four closely related, large-bodied, eastern rainforest sifakas. The other three members of this group are the diademed sifaka, Perrier's sifaka, and Milne-Edwards' sifaka
Milne-Edwards' sifaka
Milne-Edwards' sifaka , or Milne-Edwards' simpona, is a large arboreal, diurnal lemur endemic to the eastern coastal rainforest of Madagascar. Milne-Edwards' sifaka is characterized by a black body with a light-colored "saddle" on the lower part of its back. It is closely related to the diademed...
(Propithecus edwardsi). The species status of the silky sifaka, as well as other sifakas, does not have universal support: in 2007, Tattersall argued against species distinctions within Propithecus, claiming the decisions were made prematurely.
In 1974, Tattersall spotted what he thought was a color variant of the silky sifaka north of Vohemar
Vohemar
Vohemar is a coastal city and commune in northern Madagascar. It belongs to the district of Vohemar, which is a part of Sava Region. The population of the commune was estimated to be approximately 15,000 in 2001 commune census....
in northeast Madagascar. Describing it as such eight years later in The Primates of Madagascar, he not only cited its mostly white fur, but also uncharacteristic traits such as a patch of orange on its crown and tufted ears. It was not observed again until 1986, when a team led by paleoanthropologist Elwyn Simons captured specimens for captive breeding
Captive breeding
Captive breedingis the process of breeding animals in human controlled environments with restricted settings, such as wildlife reserves, zoos and other conservation facilities; sometimes the process is construed to include release of individual organisms to the wild, when there is sufficient...
and identified it as a new species, named as the golden-crowned sifaka
Golden-crowned Sifaka
The golden-crowned sifaka or Tattersall's sifaka is a medium-sized lemur characterized by mostly white fur, prominent furry ears and a golden-orange crown. It is one of the smallest sifakas , weighing around and measuring approximately from head to tail...
(Propithecus tattersalli) in 1988.
Geographic range and habitat
The silky sifaka is confined to a small region of northeastern Madagascar within a strip of humid forest stretching from MaroantsetraMaroantsetra
Maroantsetra is a market town and domestic seaport in Analanjirofo Region, Madagascar. It is located on the Bay of Antongil near .Maroantsetra is the main point of access to Masoala National Park and the Nosy Mangabe special reserve, and the headquarters of the park authority.Access to the town is...
in the south to the Andapa Basin and the Marojejy Massif in the north. Marojejy National Park
Marojejy National Park
Marojejy National Park is a national park in the Sava Region of northeastern Madagascar. It covers and is centered around the Marojejy Massif, a mountain chain that rises to an elevation of . Access to the area around the massif was restricted to research scientists when the site was set aside as...
represents the northern limit of its current distribution, although historical sifaka range maps created by Grandidier and Milne-Edwards in the late 19th century show the silky sifaka as far north as the Bemarivo River
Bemarivo River
The Bemarivo River is located in northern Madagascar. It drains to the north-eastern coast, into the Indian Ocean. It serves as the northern edge of the territory known as Betsimisaraka. Confusingly, a tributary of the Sofia River is also called the Bemarivo River.- References :...
, north of Sambava
Sambava
Sambava is a city and commune at the east coast of northern Madagascar. It is the capital of Sambava District and Sava Region. The population of the commune was estimated to be approximately 40,000 in 2001 commune census....
. The Androranga River may represent the northwestern range limit within the Tsaratanana Corridor. The southern limit of its range appears to be the Antainambalana River, within the Makira Conservation Site. It is not known if the silky sifaka has ever ranged as far south as the Masoala Peninsula. As of 2009, new observations of a few groups of the silky sifaka in unprotected forest fragments adjacent to northeastern Makira (Antohaka Lava and Maherivaratra
Maherivaratra
Maherivaratra is a municipality in Madagascar. It belongs to the district of Ambanja, which is a part of Diana Region. According to 2001 census the population of Maherivaratra was 4,151....
) may slightly enlarge the known geographic range of this species. The presence of the silky sifaka has been documented within Marojejy National Park, Anjanaharibe-Sud Special Reserve
Anjanaharibe-Sud Reserve
Anjanaharibe-Sud Reserve is a wildlife reserve of Madagascar. It was nominated to the UNESCO Tentative List of World Heritage Sites in Madagascar in 2008 as an extension to the Rainforests of the Atsinanana....
, the Makira Forest Protected Area
Makira Natural Park
The Makira Natural Park will be one of Madagascar's largest protected areas, and one of the first to be created under the president's "Durban Vision", which aims to triple the area under protection during the period 2003-2008...
, the Betaolana Corridor, and the Tsaratanana Corridor. In 2008, 16 groups were discovered in western Marojejy near Antsahaberoaka.
The silky sifaka tends to be found at higher elevations than any of the other sifaka species and also occupies the greatest range of elevations for the group. In Marojejy National Park and Anjanaharibe-Sud Special Reserve, where most of the remaining groups exist, it is not found below 700 m (2,296.6 ft) of elevation and not above 1875 m (6,151.6 ft). However, at its southernmost location in Makira (Andaparaty), several groups inhabit forest fragments at an unusually low elevation of 300 m (984.3 ft). The silky sifaka inhabits three types of elevation-specific habitats: primary montane rainforest
Cloud forest
A cloud forest, also called a fog forest, is a generally tropical or subtropical evergreen montane moist forest characterized by a persistent, frequent or seasonal low-level cloud cover, usually at the canopy level. Cloud forests often exhibit an abundance of mosses covering the ground and...
, sclerophyllous forest
Sclerophyll
Sclerophyll is the term for a type of vegetation that has hard leaves and short internodes . The word comes from the Greek sclero and phyllon ....
, and the most elevated portions of low ericoid bush
Madagascar ericoid thickets
The Madagascar ericoid thickets is a montane shrubland ecoregion, found in the high mountains of Madagascar.The ecoregion covers the area above 1800 meters elevation in separate mountain areas of Madagascar, Tsaratanana , Marojejy , Ankaratra , and Andringitra...
. It is unknown how sensitive the silky sifaka is to disturbance or whether it avoids habitat edges ("edge-intolerant") or is more edge-tolerant like the diademed sifaka. Like other rainforest sifaka species, it seldom crosses non-forested regions between forest fragments.
In the Anjanaharibe-Sud Special Reserve, the silky sifaka is sympatric (shares the same geographic range) with the white-fronted brown lemur (Eulemur albifrons) and an all-black population of indri
Indri
The indri , also called the babakoto, is one of the largest living lemurs. It is a diurnal tree-dweller related to the sifakas and, like all lemuroids, it is native to Madagascar.- Etymology :...
(Indri indri). In Marojejy National Park, it is sympatric with the white-fronted brown lemur. In 2008, it was suggested that the silky sifaka may be sympatric with the red ruffed lemur
Red Ruffed Lemur
The red ruffed lemur is one of two species in the genus Varecia, the ruffed lemurs; the other is the black-and-white ruffed lemur . Like all lemurs, it is native to Madagascar and occurs only in the rainforests of Masoala, in the northeast of the island...
(Varecia rubra) near Maherivaratra and Andaparaty.
Physical description
The silky sifaka is one of the larger sifaka species, with a head-body length of 48 –, a tail length of 45 –, a total length of 93 –, and a weight of 5 –. As its common English name suggests, its long, white furFur
Fur is a synonym for hair, used more in reference to non-human animals, usually mammals; particularly those with extensives body hair coverage. The term is sometimes used to refer to the body hair of an animal as a complete coat, also known as the "pelage". Fur is also used to refer to animal...
has a silky texture. Not all individuals are completely white: some have silver-gray or black tints on the crown, back, and limbs. The base of the tail ("pygal region") can be yellow. The ears and face are hairless, and the skin may be a mix of pink and black, completely black, or completely pink. The tips of the ears protrude slightly above the fur on the rest of the head. Its eyes have a deep orange-red coloration. Its appearance is distinctive, and since no other sifakas share its range, it is not easily confused with other lemur species.
While it is difficult to distinguish adult males and females in other eastern rainforest sifakas, such as the Perrier's sifaka and Milne-Edwards' sifaka, gender in the silky sifaka is easily discerned due to differences in fur coloration of the upper chest. Females have white fur, while males have a large brown patch of fur that results from scent marking
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
with a gland on the chest and throat (the sternal gular gland). During mating season, the size of the "chest patch" increases to cover both the chest and abdomen as a result of increased scent marking.
Behavior
Until the 21st century, brief observations and lemur surveys had merely documented the presence of the silky sifaka in special reserves and national parks. More recently, a 14-month study and two short-term studies in Marojejy National Park have revealed previously unknown details about its behavioral biology, communication, and feeding ecology. The silky sifaka has a variable social structure and is known to live in male-female pairsPair bond
In biology, a pair bond is the strong affinity that develops in some species between the males and females in a pair, potentially leading to breeding. Pair-bonding is a term coined in the 1940s that is frequently used in sociobiology and evolutionary psychology circles...
, one-male group
One-male group
One-male groups are a type of social organization where one male interacts with a group of females and their immature offspring. Offspring of both sexes are evicted from the group upon reaching puberty. It can been seen in many species of primates, including the Gelada baboon, the Patas Monkey,...
s, and multi-male/multi-female groups
Multi-male group
Multi-male groups, also known as multi-male/multi-female, are a type of social organization where the group contains more than one adult male, more than one adult female, and offspring of all ages. Within Order Primates, it is the most common social group type, with group sizes ranging from 10 to...
. Group sizes range from two to nine individuals, while the home range
Home range
Home range is the area where an animal lives and travels in. It is closely related to, but not identical with, the concept of "territory".The concept that can be traced back to a publication in 1943 by W. H. Burt, who constructed maps delineating the spatial extent or outside boundary of an...
s are estimated to range from 34 to 47 ha (0.131274733921462 to 0.181468014538491 sqmi), varying in size by location.
Personal grooming
Personal grooming is the art of cleaning, grooming, and maintaining parts of the body. It is a species-typical behavior that is controlled by neural circuits in the brain.- In humans :...
, social grooming
Social grooming
In social animals, including humans, social grooming or allogrooming is an activity in which individuals in a group clean or maintain one another's body or appearance. It is a major social activity, and a means by which animals who live in proximity can bond and reinforce social structures, family...
(allogrooming), and play. The rest of the day is spent traveling and sleeping. Other sources report that the species divides half of the day between traveling and foraging, while the rest is spent resting. Daily foraging usually starts at dawn unless delayed by rain. Group movement is usually led by females, and groups usually travel 700 m (2,296.6 ft) per day, and may climb 500 m (1,640.4 ft) along vertical slopes. Although the species spends its time in the trees, terrestrial play is not uncommon, even among adults, with play sessions lasting 30 minutes or more. Like other sifakas, it uses a type of arboreal locomotion
Arboreal locomotion
Arboreal locomotion is the locomotion of animals in trees. In every habitat in which trees are present, animals have evolved to move in them. Some animals may only scale trees occasionally, while others are exclusively arboreal. These habitats pose numerous mechanical challenges to animals...
known as vertical clinging and leaping
Vertical clinging and leaping
"Vertical clinging and leaping" is a type of arboreal locomotion seen most commonly among the strepsirrhine primates, and particularly the members of the family Indriidae. At rest, the animal clings to a vertical support, such as the side of a tree or bamboo stalk...
. Dominance hierarchies
Dominance hierarchy
A dominance hierarchy is the organization of individuals in a group that occurs when competition for resources leads to aggression...
have not been documented among female sifakas, including the silky sifaka, although seasonal hierarchies are known to occur. Aggression
Aggression
In psychology, as well as other social and behavioral sciences, aggression refers to behavior between members of the same species that is intended to cause humiliation, pain, or harm. Ferguson and Beaver defined aggressive behavior as "Behavior which is intended to increase the social dominance of...
, which is generally infrequent, occurs primarily during feeding, where females take priority over males, although submissive signals are not always obvious.
The silky sifaka's diet is similar to that of other eastern rainforest sifakas, consisting primarily of leaves (folivory
Folivore
In zoology, a folivore is a herbivore that specializes in eating leaves. Mature leaves contain a high proportion of hard-to-digest cellulose, less energy than other types of foods, and often toxic compounds. For this reason folivorous animals tend to have long digestive tracts and slow metabolisms....
) and seeds (seed predation
Seed predation
Seed predation, often referred to as granivory, is a type of plant-animal interaction in which granivores feed on the seeds of plants as a main or exclusive food source, in many cases leaving the seeds damaged and not viable...
). It is highly varied and includes many plant species. A two-month study from the mid-2000s showed that the silky sifaka can feed on as many as 76 species of plant from 42 families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
. Its favorites included primarily tree species, but also some liana
Liana
A liana is any of various long-stemmed, woody vines that are rooted in the soil at ground level and use trees, as well as other means of vertical support, to climb up to the canopy to get access to well-lit areas of the forest. Lianas are especially characteristic of tropical moist deciduous...
s. The most prominent plant families in the diet were Moraceae
Moraceae
Moraceae — often called the mulberry family or fig family — are a family of flowering plants comprising about 40 genera and over 1000 species. Most are widespread in tropical and subtropical regions, less so in temperate climates...
(20.30%), Fabaceae
Fabaceae
The Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, is a large and economically important family of flowering plants. The group is the third largest land plant family, behind only the Orchidaceae and Asteraceae, with 730 genera and over 19,400 species...
(12.87%), Myrtaceae
Myrtaceae
The Myrtaceae or Myrtle family are a family of dicotyledon plants, placed within the order Myrtales. Myrtle, clove, guava, feijoa, allspice, and eucalyptus belong here. All species are woody, with essential oils, and flower parts in multiples of four or five...
(12.65%), Clusiaceae
Clusiaceae
The Clusiaceae or Guttiferae Juss. is a family of plants formerly including about 37 genera and 1610 species of trees and shrubs, often with milky sap and fruits or capsules for seeds. It is primarily tropical...
(10.13%) and Apocynaceae
Apocynaceae
The Apocynaceae or dogbane family is a family of flowering plants that includes trees, shrubs, herbs, and lianas.Many species are tall trees found in tropical rainforests, and most are from the tropics and subtropics, but some grow in tropical dry, xeric environments. There are also perennial herbs...
(9.49%). In the study, feeding upon these four plant families took up as much as 37.06% of the total feeding time for the silky sifaka: 16.09% on the fruit of Pachytrophe dimepate, 8.43% on the seeds of Senna
Senna (genus)
Senna , the sennas, is a large genus of flowering plants in the family Fabaceae, subfamily Caesalpinioideae. This diverse genus is native throughout the tropics, with a small number of species reaching into temperate regions. The number of species is usually estimated to be about 260, but some...
sp., 6.52% on the young leaves of Plectaneia thouarsii, and 6.02% on the fruit of Eugenia
Eugenia
Eugenia is a genus of flowering plants in the myrtle family Myrtaceae. It has a worldwide, although highly uneven, distribution in tropical and subtropical regions. The bulk of the approximately 1,000 species occur in the New World tropics, especially in the northern Andes, the Caribbean, and the...
sp. In sum, folivory accounted for 52% of the feeding time, while frugivory
Frugivore
A frugivore is a fruit eater. It can be any type of herbivore or omnivore where fruit is a preferred food type. Because approximately 20% of all mammalian herbivores also eat fruit, frugivory is considered to be common among mammals. Since frugivores eat a lot of fruit they are highly dependent...
(fruit-eating) accounted for 34%, and seed predation made up 11%. The consumption of flowers, as well as soil (geophagy
Geophagy
Geophagy is the practice of eating earthy or soil-like substances such as clay, and chalk. It exists in animals in the wild and also in humans, most often in rural or preindustrial societies among children and pregnant women...
), was rarely observed in this study. Prior to this, preliminary studies had reported that folivory account for 75% of the diet, while fruits and 15% was seed predation, 7% was flower consumption, and bark and soil made up the remainder.
Like all other lemurs, the silky sifaka is a seasonal breeder
Seasonal breeder
Seasonal breeders are animal species that successfully mate only during certain times of the year. These times of year allow for the births at a time optimal for the survival of the young in terms of factors such as temperature, food and water. Related sexual interest and behaviors are expressed...
, and it is thought that it mates
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...
only one day a year during the start of the rainy season sometime in December or January. Infants are born six months later in June or July. Females typically give birth to a single infant once every two years, although births in consecutive years have been observed. Infants initially cling to the fur of their mother's chest for nearly four weeks and then switch to riding on her back. As with other eastern rainforest sifakas, the infants of this species develop rapidly. This may be due to assistance in the care of infants by all group members (known as alloparental care)—a trait typical among all sifakas. Non-maternal care usually takes the form of allogrooming, but also playing, occasional carrying, and in rare cases, nursing. The dispersal of offspring is thought to be similar to that of other eastern rainforest sifakas, with both males and females transferring out of the group at sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
. However, dispersal has only been observed once with a young adult male, who left its natal group and proceeded to oust an older male from a group in which he had been a member for seven years. Female dispersal and group transfer has not yet been observed.
The only documented predator of the silky sifaka, other than humans, is the fossa
Fossa (animal)
The fossa is a cat-like, carnivorous mammal that is endemic to Madagascar. It is a member of the Eupleridae, a family of carnivorans closely related to the mongoose family . Its classification has been controversial because its physical traits resemble those of cats, yet other traits suggest a...
, a cat-like carnivore
Feliformia
The Feliformia are a suborder within the order Carnivora and includes cats , hyenas, mongooses, civets and related taxa. The other suborder of Carnivora is Caniformia...
found only on Madagascar. Although no aerial predators are known, the silky sifaka often watch the sky and emit loud "aerial disturbance" roars at the sight of the large Madagascar buzzard
Madagascar Buzzard
The Madagascar Buzzard is a species of bird of prey in the Accipitridae family.It is endemic to Madagascar.Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical moist montane forests....
(Buteo brachypterus) and other small birds. Another more general alarm call is the loud, sneeze-like "zzuss" vocalization
Animal communication
Animal communication is any behavior on the part of one animal that has an effect on the current or future behaviour of another animal. The study of animal communication, is sometimes called Zoosemiotics has played an important part in the...
, which are emitted in response to terrestrial disturbances, calls from lost group members, and aggression by other group members. Acoustic analyses of the "zzuss" vocalization have shown that the call's acoustic
Acoustics
Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics...
structure differs between individuals and by gender.
Adult eastern sifakas have a moderately sized vocal repertoire of about seven call types. It is uncertain if their vocalizations have specific or varied contexts, and as with other primates, arousal level may play a role in the acoustic structure of its calls. Despite the limited size of the silky sifaka's vocal repertoire, it does exhibit high call rates of seven calls per hour, on average. Even infants are known to have several specialized vocalizations. The most frequently emitted silky sifaka vocalizations are low-amplitude, low-frequency, tonal "hum" and "mum" vocalizations. These contact calls are used in a variety of circumstances including group movement, affiliation, foraging, and while resting.
The silky sifaka uses well-developed olfactory
Olfaction
Olfaction is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates...
(smell-based) communication, as with all other prosimian
Prosimian
Prosimians are a grouping of mammals defined as being primates, but not monkeys or apes. They include, among others, lemurs, bushbabies, and tarsiers. They are considered to have characteristics that are more primitive than those of monkeys and apes. Prosimians are the only primates native to...
("pre-monkey") primates. Like other eastern rainforest sifakas, it has several specialized glands for scent-marking
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
, including a sebaceous gland
Sebaceous gland
The sebaceous glands are microscopic glands in the skin that secrete an oily/waxy matter, called sebum, to lubricate and waterproof the skin and hair of mammals...
on the chest, found only in males, and mixed apocrine-sebaceous glands on the genitals
Sex organ
A sex organ, or primary sexual characteristic, as narrowly defined, is any of the anatomical parts of the body which are involved in sexual reproduction and constitute the reproductive system in a complex organism; flowers are the reproductive organs of flowering plants, cones are the reproductive...
in both sexes. Unlike the true lemurs of the genus Eulemur, the silky sifaka does not directly scent-mark its conspecifics (allomarking), although it does scent-mark its territory. Both sexes will often urinate while scent-marking. Males and females scent-mark in different ways: females rub their genital glands in an up-and-down motion against trees, while males may use their chest gland, genital glands, or a combination of both. Males will also use their specialized prosimian toothcomb
Toothcomb
A toothcomb is an anatomical structure found in strepsirrhine primates, which includes lemurs, lorises and galagos. A toothcomb consists of long, flat forward-angled teeth, and includes the lower incisors and the canine teeth...
to gouge trees before scent-marking with their chest—a behavior that leaves long-lasting visible marks. The gouging is thought to serve a role in communication and has no dietary component, since males do not eat the bark or tree gum.
Males scent-mark more frequently than females, as much as two or three times as often. Males also respond to female scent-marking by overmarking with their own scent glands, usually by combining chest and genital marking. They will also overmark other males, although less quickly and less often. In a one-year study, males responded to 71% of the marks made by females within an average of 61 seconds while only 17% of male marks received a response from other group members. Because males overmark frequently, this results in "totem-tree marking", where certain trees become covered by male scent and gouge marks. However, no observations of widespread home range border scent-marking have been reported. Scent-marks are usually left on trees in the core area of the home range, as opposed to the territorial boundaries.
Conservation
Critically Endangered
Critically Endangered is the highest risk category assigned by the IUCN Red List for wild species. Critically Endangered means that a species' numbers have decreased, or will decrease, by 80% within three generations....
. It is one of the rarest and most critically endangered lemurs. The silky sifaka is one of five lemurs listed as one of "The World's 25 Most Endangered Primates
The World's 25 Most Endangered Primates
The World's 25 Most Endangered Primates is a list of highly endangered primate species selected and published by the International Union for Conservation of Nature Species Survival Commission Primate Specialist Group , the International Primatological Society , and Conservation International...
" and has been on the list all five times since its inception in 2000. Its population size is estimated to range between 100 and 1,000 individuals, while the number of mature individuals is thought to be less than 250. There are no silky sifakas in captivity, such as in zoos.
The silky sifaka is the flag-ship species
Flagship species
The concept of flagship species is a surrogate species concept with its genesis in the field of conservation biology. The flagship species concept holds that by raising the profile of a particular species, it can successfully leverage more support for biodiversity conservation at large in a...
for the protected areas in which it is found, particularly for Marojejy, which has recently been inaugurated as part of a World Heritage Site
World Heritage Site
A UNESCO World Heritage Site is a place that is listed by the UNESCO as of special cultural or physical significance...
cluster known as the Rainforests of the Atsinanana
Rainforests of the Atsinanana
The Rainforests of the Atsinanana is a World Heritage Site that was inscribed in 2007 and consists 13 specific areas located within six national parks in the eastern part of Madagascar...
. Habitat disturbance, such as slash-and-burn agriculture
Slash and burn
Slash-and-burn is an agricultural technique which involves cutting and burning of forests or woodlands to create fields. It is subsistence agriculture that typically uses little technology or other tools. It is typically part of shifting cultivation agriculture, and of transhumance livestock...
(known locally as tavy), logging of precious woods (e.g., rosewood
Rosewood
Rosewood refers to any of a number of richly hued timbers, often brownish with darker veining, but found in many different hues. All rosewoods are strong and heavy, taking an excellent polish, being suitable for guitars, marimbas, turnery , handles, furniture, luxury flooring, etc.In general,...
) and fuel-wood, also occurs within the protected areas where it is found. Unlike the golden-crowned sifaka
Golden-crowned Sifaka
The golden-crowned sifaka or Tattersall's sifaka is a medium-sized lemur characterized by mostly white fur, prominent furry ears and a golden-orange crown. It is one of the smallest sifakas , weighing around and measuring approximately from head to tail...
(Propithecus tattersalli), there is no local taboo (fady) against eating this species, and the hunting of bushmeat
Bushmeat
Bushmeat initially referred to the hunting of wild animals in West and Central Africa and is a calque from the French viande de brousse. Today the term is commonly used for meat of terrestrial wild animals, killed for subsistence or commercial purposes throughout the humid tropics of the Americas,...
is a known issue within its range. It is most heavily hunted in the northern and western parts of Marojejy, as well as other areas around the Andapa Basin. The species is restricted to 90000 ha (347.5 sq mi) of protected areas, although this may be an overestimation because in much of its range the silky sifaka is not found below 700 m (2,296.6 ft) in altitude, possibly due to either hunting pressure or habitat preference.
Illegal logging
Illegal logging in Madagascar
Illegal logging has been a problem in Madagascar for decades and is perpetuated by extreme poverty and government corruption. Often taking the form of selective logging, the trade has been driven by high international demand for expensive, fine-grained lumber such as rosewood and ebony...
of precious hardwoods, such as rosewood and ebony
Ebony
Ebony is a dense black wood, most commonly yielded by several species in the genus Diospyros, but ebony may also refer to other heavy, black woods from unrelated species. Ebony is dense enough to sink in water. Its fine texture, and very smooth finish when polished, make it valuable as an...
, has become one of the greatest threats to the silky sifaka's habitat, especially since the 2009 Malagasy political crisis. Its two largest protected areas, Masoala National Park and Marojejy National Park, have been the hardest hit. The disturbance caused by selective logging increases the likelihood of forest fires, helps invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
take root, impairs habitat, and causes the loss of genetic diversity
Genetic diversity
Genetic diversity, the level of biodiversity, refers to the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary....
.
Local villages adjacent to its remaining protected areas adopted a two-pronged strategy towards silky sifaka conservation education. First, a "cognitive component" was implemented to increase knowledge and awareness through radio interviews, slide presentations, and the disbursement of literature in twelve primary and secondary schools. Additionally, an "emotional component" was begun to link silky sifaka conservation with positive emotional experiences, with the goal of establishing a psychological connection between the children and the lemur. To do this, groups of children were taken on three-day educational eco-tours
Ecotourism
Ecotourism is a form of tourism visiting fragile, pristine, and usually protected areas, intended as a low impact and often small scale alternative to standard commercial tourism...
in Marojejy National Park. Both the teachers and the students showed interest and genuine concern about the plight of the silky sifaka.
Plans are being made to both expand Anjanaharibe-Sud Special Reserve and link existing parks and reserves in the region with wildlife corridors
Habitat corridor
A habitat corridor is a strip of land that aids in the movement of species between disconnected areas of their natural habitat. An animal’s natural habitat would typically include a number of areas necessary to thrive, such as wetlands, burrowing sites, food, and breeding grounds...
. These corridors include the Betaolana Corridor between Marojejy and Anjananharibe-Sud and Makira, which will connect Anjananharibe-Sud with Masoala National Park
Masoala National Park
Masoala National Park, in northeast Madagascar, is the largest of the island's protected areas. Most of the park is situated in Sava Region and a part in Analanjirofo. Created in 1997, the park protects 2,300 square kilometres of rainforest and 100 square kilometres of marine parks. The Masoala...
to the south. In addition to providing additional habitat for the silky sifaka, the corridors would promote genetic exchange between currently isolated populations.
External links
- Trouble in Lemur Land – a professional 50 minute HD film about illegal rosewood logging in Madagascar and the impact on the silky sifaka lemur
- Silky sifaka research and conservation website
- Wildlife photographer Kevin Schafer's silky sifaka photos
- Silky sifaka documentary on Erik Patel's research in Marojejy N.P.
- Carte Blanche news program featuring the silky sifaka and illegal rosewood logging
- Dan Rather Reports news program featuring the silky sifaka and illegal rosewood logging
- Silky sifaka expert from Madagascar receives Seacology Prize