Silky Sifaka

Taxobox
name = Silky Sifaka [cite journal | author = Mireya I. Mayor, Julie A. Sommer, Marlys L. Houck, John R. Zaonarivelo, Patricia C. Wright, Colleen Ingram, Stacia R. Engel and Edward E. Louis Jr. | title = Specific Status of "Propithecus" spp. | journal = International Journal of Primatology | volume = 25 | issue = 4 | month = August | year = 2004 | pages = 875-900 | id = doi|10.1023/B:IJOP.0000029127.31190.e9]


status = CR
trend = unknown
status_system = iucn3.1
status_ref = IUCN2007 | assessors = Ganzhorn, J. & Members of the Primate Specialist Group | year = 2000 | title = Propithecus diadema "ssp." candidus | id = 18360 | downloaded = 2008-05-02]
regnum = Animalia
phylum = Chordata
classis = Mammalia
ordo = Primates
familia = Indriidae
genus = "Propithecus"
species = "P. candidus"
binomial = "Propithecus candidus"
binomial_authority = A. Grandidier, 1871

The Silky Sifaka ("Propithecus candidus") is a white, diurnal rainforest sifaka found solely within a small area of northeastern Madagascar. This folivorous primate is highly social, patchily distributed, and found at low densities.cite journal | author = Mittermeier, R. A., Ratsimbazafy, J., Rylands, A. B., Williamson, L., Oates, J. F., & Mbora, D. | year = 2007 | title = Primates in Peril: The World's 25 Most Endangered Primates, 2006-2008 | journal = Primate Conservation | volume = 22 | pages = 1-40] It is threatened by habitat destruction and hunting, and is currently considered one of the 25 most endangered primates in the world.

Description

This primate has a head-body length of 48-54 cm, a tail length of 45-51 cm, and a weight of 5-6 kg.cite book | author = Mittermeier, R. A., Konstant, W. R., Hawkins, F., Louis Jr., E. E., Langrand, O., Ratsimbazafy, J., et al. | year = 2006 | title = Lemurs of Madagascar | edition = 2nd edition | series = Tropical Field Guide Series | publisher = Conservation International | location = Washington, D.C.] The Silky Sifaka is intermediate in size between the Diademed Sifaka ("P. diadema") and Perrier's Sifaka ("P. perrieri").cite journal | author = Lehman, S. M., Mayor, M., & Wright, P. C. | year = 2005 | title = Ecogeographic size variations in sifakas: A test of the resource seasonality and resource quality hypotheses | journal = American Journal of Primatology | volume = 126 | issue = 3 | pages = 318-28] Its muzzle and face are bare and the skin is a mix of pink and black, though some individuals have entirely pink or black faces. Adult males and females are easily determined by the upper chest fur color: adult males have a large brown "chest patch" due to chest scent-marking.

Range and habitat

The Silky Sifaka has a very restricted range. This lemur is found in only a few protected areas: Marojejy National Park, Anjanaharibe-Sud Special Reserve, and rarely in the Anjanaharibe and Manandriana areas of Makira Protected Area, north of the Antainambalana River. Marojejy is considered the northern limit of its distribution, with the Antainambalana River as the southern limit. The maximum vertical elevation of the primate (525 meters) was found to exceed other sifakas.cite journal | author = Santorelli, C. J., Parathian, H. E., & Patel, E. R. | year = 2006 | title = Silky Sifaka ("Propithecus candidus") Ranging, Activity Budget and Demography | journal = International Journal of Primatology | issue = Supplement | volume = 27 | pages = 322-3] Home range size can exceed 40 ha.cite journal | author = Patel, E. R. | year = 2006a | title = Activity budget, ranging, and group size in silky sifakas ("Propithecus candidus") | journal = Lemur News | volume = 11 | pages = 42-45]

Behaviour

Diet

The primate's diet is highly folivorous, eating both mature and young leaves, as well as fruit, flowers, seeds, bark, soil and roots. A study taken during the non-fruiting season reported that mature and young leaves consisted of 75% of the primate's food intake, fruit and seeds were 15%, flowers were 7%, and bark and soil accounted for the remainder of the diet.cite journal | author = Kelley, E., & Mayor, M.I. | year = 2002 | title = Preliminary study of the silky sifaka ("Propithecus diadema candidus") in northeast Madagascar | journal = Lemur News | volume = 7 | pages = 16-18] Males were found to eat mature leaves, fruit, seeds, soil and bark more than females, while females ate more young leaves and flowers than the males.

Range and activity budget

The first long-term study (14.5 months) of the silky sifaka examined ranging, activity budget, and demography in Marojejy National Park. The Silky Sifaka home range size and daily path length was found to resemble published values of other rainforest sifakas (though Milne-Edward's Sifaka ("P. edwardsi") may have a larger home range and "P. diadema" may have a longer day range). Activity budgets showed that the primates spend most of their time resting (45%), foraging (22%) and engaging in social behavior (16%). Differences between adult males and females were also apparent: females foraged and rested more than males, while males spent more time in movement and in social behavior. The average daily travel duration for the primate was 57.5 minutes.

ocial structure

The social structure of the primate is variable, both pair-living and polygynandrous. One study came across six groups in Marojejy and Anjanaharibe-Sud Special Reserve: three were multi-male multi-female groups, and the remaining three were single adult pairs, both with and without offspring. Group sizes vary from 2 to 9 individuals.

Documented social behavior includes examples of both "submissive behaviors" (such as pushing, biting, cuffing, and chasing) as well as "affiliative behaviors" (such as grooming bouts and huddling).

Mating

Silky Sifaka mating occurs for only a few days each year between November and January, and young are born in June or July.cite journal | author = Patel, E.R., Coke, C.S., Richie, A., & Santorelli, C. | year = 2003a | title = Alloparental care (including allonursing) in free ranging silky sifakas ("Propithecus diadema candidus") in primary noretheastern montane rain forest in Madagascar | journal = American Journal of Primatology | issue = Supplement | volume = 60 | pages = 71-72] The primate's litter size is always one, while the inter-birth interval for females is generally two years. For the first four weeks after birth, infants grasp the fur of their mother's belly before switching to ride on her back. Offspring typically sleep with their mothers until maturity.

cent-marking

The repeated scent-marking of a tree is referred to as "totem-tree marking".cite journal | author = Ritchie, A., & Patel, E. R. | year = 2006 | title = The Existence and Potential Function of “Totem-Tree” Scent-Marking in Silky Sifakas ("Propitheucs candidus") | journal = International Journal of Primatology | issue = Supplement | volume = 27 | pages = 373-4] The adult male scent-mark rate is more than double the rate of adult females. For males, the overall rate of chest scent-marking peaks during mating season. The influence of sexual selection on olfactory communication is consistent with more general findings in other rainforest sifakas.cite journal | author = Patel, E. R. | year = 2006c | title = Scent-Marking in Wild Silky Sifakas ("Propithecus candidus") in Madagascar: Sex Differences and Seasonal Effects in Usage and Response Across Multiple Scent-Mark Types | journal = International Journal of Primatology | issue = Supplement | volume = 27 | pages = 484-5] Research has determined that these totem-trees are not territory demarcations but instead are a sign of intra-sexual male competition for females.

Predators

Aside from human beings, the only natural predator of the silky sifaka is the fossa ("Cryptoprocta ferox"), an animal particularly adept at eating lemurs.cite journal | author = Patel, E.R. | year = 2005 | title = Silky sifaka ("Propithecus candidus") predation by a fossa ("Cryptoprocta ferox") | journal = Lemur News | volume = 10 | pages = 25-27] No attempts at aerial predation on the Silky Sifaka by raptors have ever been observed, yet the animal occasionally stares at the sky and emits "aerial disturbance" noises in the direction of the Madagascar Buzzard ("Buteo brachypterus"). In one 10-month study, over 1000 anti-predator vocalizations were recorded, but only 19% of these roars occurred while a raptor was in proximity.cite journal | author = Patel, E.R., Coke, C.S., Richie, A., & Santorelli, C. | year = 2003b | title = Assessing production specificity of free-ranging silky sifaka ("Propithecus candidus") “anti-predator” vocalizations: weak evidence for “aerial predator” but not “terrestrial predator” calls (Abstract) | journal = American Journal of Primatology | issue = Supplement | volume = 60 | pages = 71-72]

Conservation issues

The remaining population of the Silky Sifaka is estimated to be as low as a few hundred individuals. In 1994, the IUCN Red List assessment listed "P. diadema candidus" as Critically Endangered [CR A2cd, B1 + 2bc] . Since this assessment has not been updated for over a decade, the primate's category should now be considered [CR C1 + 2a(i)] .

The primary conservation threat appears to be hunting and habitat disturbance. It is hunted by locals for delicacy food,cite journal | author = Patel, E. R. | year = 2006b | title = Appealing to Hearts and Minds: Silky Sifaka ("Propithecus candidus") Conservation Education in North-Eastern Madagascar | journal = American Journal of Primatology | issue = Supplement | volume = 68 | pages = 87] as there is no local "fady" (or taboo) against eating the species. Habitat disturbance occurs within and adjacent to the primate's protected areas. This is due to slash-and-burn agriculture and logging, both for precious woods and for fuel-wood.

Local villages adjacent to its remaining protected areas adopted a two-pronged strategy towards Silky Sifaka conservation education. 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, and 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. The children's reactions to their up-close observations of the sifakas were "overwhelmingly positive and empathic".

Efforts are underway to expand Anjananharibe-Sud Special Reserve and to link existing parks and reserves through protection of continuous forest "corridors".cite book | title = The Lemurs of Marojejy and Anjananharibe-Sud | edition = Brochure | year = 2007 | publisher = Marojejy National Park | location = Madagascar] These include Betaolana between Marojejy and Anjananharibe-Sud, and Makira, linking Anjananharibe-Sud with Masoala National Park to the south. The corridors will provide much-needed habitat for forest-dependent species like the Silky Sifaka. In addition, the corridors would provide the possibility of increasing genetic exchange between populations.

In May 2006 the WWF launched a project to use community-based natural resource management (CBNRM) to save this sifaka and its habitat. The project seeks to increase the education and awareness of local populations and to make them an active part in the management and habitat conservation of the lemur. It focuses on the corridor of Marojejy to southern Anjananharibe in the northern section and the Marojejy-Tsaratanana corridor in the western section. Ideally, the project hopes to transfer management of the lemurs and their habitat to local populations.cite web | title = Conservation of Lemurs in the Marojejy-Tsaratanana Corridor | year = 2006 | work = World Wide Fund for Nature | accessdate = 2008-04-14 | url = http://www.panda.org/about_wwf/where_we_work/project/projects/index.cfm?uProjectID=MG0896]

References

External links

* [http://pin.primate.wisc.edu/factsheets/entry/diademed_sifaka Primate Info Net Eastern Sifakas Factsheet]
* [http://www.erikpatel.com/ Erik Patel's site on Silky Sifakas]
* [http://www.primate-sg.org/candidus07.htm Primate Specialist Group]