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{{Taxobox
{{Taxobox
| name = Silky Sifaka<ref>{{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}}}}</ref>
| name = Silky Sifaka
| status = CR
| status = CR
| trend = unknown
| trend = unknown
| status_system = iucn2.3
| status_system = iucn2.3
| status_ref = <ref name=iucn>{{IUCN2007 | assessors = Ganzhorn, J. & Members of the Primate Specialist Group | year = 2000 | title = Propithecus diadema ''ssp.'' candidus | id = 18360 | downloaded = [[2008-05-02]]}}</ref>
| status_ref =
| image =
| image_width = 210px
| regnum = [[Animal]]ia
| regnum = [[Animal]]ia
| phylum = [[Chordata]]
| phylum = [[Chordata]]
Line 18: Line 16:
}}
}}


''P. candidus'' is a white, diurnal rainforest [[sifaka]] found solely within a small area of northeastern [[Madagascar]]. They are highly social, patchily distributed, and found at low densities<ref>Mittermeier, 2007</ref>. The [[primate]] has a head-body length of 48-54 cm, a tail length of 45-51 cm, and a weight of 5-6 kg<ref>Mittermeier, 2006</ref>. ''P. candidus'' is intermediate in size between ''[[P. diadema]]'' and ''P. perrieri''<ref>Lehman, 2005</ref>. 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<ref>Mittermeier, 2006</ref>. 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.
The '''Silky Sifaka''' (''P. candidus'') is a white, [[diurnal]] [[rainforest]] [[sifaka]] found solely within a small area of northeastern [[Madagascar]]. It is highly social, patchily distributed, and found at low densities.<ref name=Mittermeier2007>{{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}}</ref>. 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.<ref name=Mittermeier2006>{{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 DC}}</ref> The Silky Sifaka is intermediate in size between the [[Diademed Sifaka]] ''P. diadema'' and [[Perrier's Sifaka]] ''P. perrieri''.<ref name=Lehman2005>{{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}}</ref> 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.<ref name=Mittermeier2006/> 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==
==Range and habitat==
The silky sifaka has a very restricted range. They are 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<ref>Mittermeier, 2007</ref>. Marojejy is considered the northern limit of its distribution, with the Antainambalana River as the southern limit<ref>Mittermeier, 2006</ref>. The maximum vertical elevation of the primate (525 meters) was found to exceed other sifakas<ref>Santorelli, 2006</ref>. Home range size can exceed 40 ha<ref>Patel, 2006a</ref>.
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.<ref name=Mittermeier2007/> Marojejy is considered the northern limit of its distribution, with the Antainambalana River as the southern limit.<ref name=Mittermeier2006/> The maximum vertical elevation of the primate (525 meters) was found to exceed other sifakas.<ref name=Santorelli2006>{{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}}</ref> Home range size can exceed 40 ha.<ref name=Patel2006a>{{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}}</ref>
==Behaviour==
==Behaviour==
The primate’s [[diet]] is highly [[folivorous]], eating both mature and young [[leaves]], as well as [[fruit]], [[flowers]], [[seeds]], [[bark]], [[soil]], and roots<ref>Mittermeier, 2007</ref>. 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<ref>Kelley & Mayor, 2002</ref>. 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.
The primate's [[diet]] is highly [[folivorous]], eating both mature and young [[leaves]], as well as [[fruit]], [[flower]]s, [[seed]]s, [[bark]], [[soil]], and roots.<ref name=Mittermeier2007/> 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.<ref name=KelleyMayor2002>{{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}}</ref> 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.


The first long-term study (14.5 months) of the silky sifaka examined ranging, activity budget, and demography in Marojejy National Park<ref>Santorelli, 2006</ref>. 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.
The first long-term study (14.5 months) of the silky sifaka examined ranging, activity budget, and demography in Marojejy National Park.<ref name=Santorelli2006/> 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.


The social structure of the primate is variable, both pair-living and [[polygynandrous]]<ref>Patel, 2006a</ref>. 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<ref>Santorelli, 2006</ref>. Group sizes vary from 2 to 9 individuals<ref>Patel, 2006a</ref>.
The social structure of the primate is variable, both pair-living and [[polygynandrous]].<ref name=Patel2006a/> 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.<ref name=Santorelli2006/> Group sizes vary from 2 to 9 individuals.<ref name=Patel2006a/>


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<ref>Kelley & Mayor, 2002</ref>.
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).<ref name=KelleyMayor2002/>


Silky sifaka [[mating]] occurs for only a few days each year between [[November]] and [[January]], and young are born in [[June]] or [[July]]<ref>Patel, Coke, Ritchie & Santorelli, 2003a</ref>. The primate’s [[litter (animal)|litter]] size is always one, while the inter-birth interval for females is generally two years<ref>Santorelli, 2006</ref>. 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]]<ref>Patel et al, 2003a</ref>.
Silky Sifaka [[mating]] occurs for only a few days each year between [[November]] and [[January]], and young are born in [[June]] or [[July]].<ref name=Patel2003a>{{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}}</ref> The primate's [[litter (animal)|litter]] size is always one, while the inter-birth interval for females is generally two years.<ref name=Santorelli2006/> 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]].<ref name=Patel2003a/>


The repeated [[scent marking|scent-marking]] of a tree is referred to as “totem-tree marking”<ref>Ritchie, 2006</ref>. 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<ref>Patel, 2006c</ref>. Research has determined that these totem-trees are not territory demarcations but instead are a sign of intra-sexual male competition for females<ref>Ritchie, 2006</ref>.
The repeated [[scent marking|scent-marking]] of a tree is referred to as "totem-tree marking".<ref name=Ritchie2006>{{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}}</ref> 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.<ref name=Patel2006c>{{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}}</ref> Research has determined that these totem-trees are not territory demarcations but instead are a sign of intra-sexual male competition for females.<ref name=Ritchie2006/>


Aside from human beings, the only natural predator of the silky sifaka is the [[fossa (animal)|fossa]] (‘’Cryptoprocta ferox’’), an animal particularly adept at eating lemurs<ref>Patel, 2005</ref>. No attempts at aerial predation on the silky sifaka by ]]Bird of Prey|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<ref>Patel, Coke, Ritchie & Santorelli, 2003b</ref>.
Aside from human beings, the only natural predator of the silky sifaka is the [[fossa (animal)|fossa]] (‘’Cryptoprocta ferox’’), an animal particularly adept at eating lemurs.<ref name=Patel2005>{{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}}</ref> No attempts at aerial predation on the Silky Sifaka by [[Bird of prey|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.<ref name=Patel2003b>{{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}}</ref>


==Conservation Issues==
==Conservation issues==
The remaining population of silky sifakas is estimated to be as low as a few hundred individuals<ref>Mittermeier, 2006</ref>. In 1994, the [[IUCN Red List]] assessment listed ‘’P. candidus’’ as Critically Endangered [CR A2cd, B1 + 2bc]. Since this assessment has not been updated for over a decade, Mittermeier (2006) denotes the primate’s category as currently [CR C1 + 2a(i)].
The remaining population of the Silky Sifaka is estimated to be as low as a few hundred individuals.<ref name=Mittermeier2006/> In 1994, the [[IUCN Red List]] assessment listed ''P. diadema candidus'' as [[Critically Endangered]] [CR A2cd, B1 + 2bc].<ref name=iucn/> Since this assessment has not been updated for over a decade, the primate's category should now be considered [CR C1 + 2a(i)].<ref name=Mittermeier2006/>


Their primary conservation threat appears to be hunting and [[habitat destruction|habitat disturbance]]. They are hunted by locals for delicacy food<ref>Patel, 2006b</ref>, as there is no local ‘’fady’’ (or [[taboo]]) against eating the species<ref>Patel ''et al''., 2003b</ref>. 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<ref>Mittermeier, 2007</ref>.
The primary conservation threat appears to be hunting and [[habitat destruction|habitat disturbance]]. It is hunted by locals for delicacy food,<ref name=Patel2006b>{{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}}</ref> as there is no local ''fady'' (or [[taboo]]) against eating the species.<ref name=Patel2003b/> 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.<ref name=Mittermeier2007/>


Local villages adjacent to its remaining protected areas adopted a two-pronged strategy towards silky sifaka conservation education<ref>Patel, 2006b</ref>. A “cognitive component” was implemented to increase knowledge and awareness through [[radio]] interviews, slide presentations, and the disbursement of literature in twelve [[primary school|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 lemurs. To do this, groups of children were taken on 3-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”<ref>Patel, 2006b</ref>.
Local villages adjacent to its remaining protected areas adopted a two-pronged strategy towards Silky Sifaka conservation education.<ref name=Patel2006b/> A "cognitive component" was implemented to increase knowledge and awareness through [[radio]] interviews, slide presentations, and the disbursement of literature in twelve [[primary school|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 3-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".<ref name=Patel2006b/>


Efforts are underway to expand Anjananharibe-Sud Special Reserve and to link existing parks and reserves through protection of continuous forest “corridors”<ref>''Lemurs'', 2007</ref>. 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<ref>''Lemurs'', 2007</ref>.
Efforts are underway to expand Anjananharibe-Sud Special Reserve and to link existing parks and reserves through protection of continuous forest "corridors".<ref name=Lemurs2007>{{cite book | title = The Lemurs of Marojejy and Anjananharibe-Sud | edition = Brochure | year = 2007 | publisher = Marojejy National Park | location = Madagascar}}</ref> 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<ref name=Lemurs2007/>


In May 2006 the [[World Wide Fund for Nature|WWF]] launched a project to use community-based natural resource management (CBNRM) to save these sifakas and their 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 lemurs. 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<ref>''Conservation'', 2006</ref>.
In May 2006 the [[World Wide Fund for Nature|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.<ref name=Conservation2006>{{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}}</ref>


==Notes==
==References==
{{reflist}}
{{reflist}}
<!-- This ref is not used

==References==
*Conservation of Lemurs in the Marojejy-Tsaratanana Corridor. (2006). World Wide Fund for Nature. Retrieved April 14, 2008, from: http://www.panda.org/about_wwf/where_we_work/project/projects/index.cfm?uProjectID=MG0896
*Kelley, E., & Mayor, M.I. (2002). Preliminary study of the silky sifaka (''Propithecus diadema candidus'') in northeast Madagascar. ''Lemur News'', 7, 16-18.
*Lehman, S. M., Mayor, M., & Wright, P. C. (2005). Ecogeographic size variations in sifakas: A test of the resource seasonality and resource quality hypotheses. ''American Journal of Primatology'', 126 (3), 318-28.
*''The Lemurs of Marojejy and Anjananharibe-Sud'' [Brochure]. (2007). Marojejy National Park , Madagascar.
*Mittermeier, R. A., Konstant, W. R., Hawkins, F., Louis Jr., E. E., Langrand, O., Ratsimbazafy, J., et al. (2006). ''Lemurs of Madagascar''. 2nd edition. Tropical Field Guide Series, Conservation International, Washington DC.
*Mittermeier, R. A., Ratsimbazafy, J., Rylands, A. B., Williamson, L., Oates, J. F., & Mbora, D. (2007). Primates in Peril: The World’s 25 Most Endangered Primates, 2006-2008. ''Primate Conservation'', 22, 1-40.
*Patel, E.R. (2005). Silky sifaka (''Propithecus candidus'') predation by a fossa (''Cryptoprocta ferox''). ''Lemur News'', 10, 25-27.
*Patel, E. R. (2006a). Activity budget, ranging, and group size in silky sifakas (''Propithecus candidus''). ''Lemur News'', 11, 42-45.
*Patel, E. R. (2006b). Appealing to Hearts and Minds: Silky Sifaka (''Propithecus candidus'') Conservation Education in North-Eastern Madagascar. ''American Journal of Primatology'' (Supplement), 68, 87.
*Patel, E. R. (2006c). Scent-Marking in Wild Silky Sifakas (''Propithecus candidus'') in Madagascar: Sex Differences and Seasonal Effects in Usage and Response Across Multiple Scent-Mark Types. ''International Journal of Primatology'' (Supplement), 27, 484-5.
*Patel, E. R., Anderson, J. D., & Owren, M. J. (2006). Exploring the Function of “Zzuss” Alarm Vocalizations in Wild Silky Sifakas (''Propithecus candidus''): Moderate Evidence for Individual Distinctiveness. ''International Journal of Primatology'' (Supplement), 27, 491-2.
*Patel, E. R., Anderson, J. D., & Owren, M. J. (2006). Exploring the Function of “Zzuss” Alarm Vocalizations in Wild Silky Sifakas (''Propithecus candidus''): Moderate Evidence for Individual Distinctiveness. ''International Journal of Primatology'' (Supplement), 27, 491-2.
-->
*Patel, E.R., Coke, C.S., Richie, A., & Santorelli, C. (2003a). Alloparental care (including allonursing) in free ranging silky sifakas (''Propithecus diadema candidus'') in primary noretheastern montane rain forest in Madagascar. ''American Journal of Primatology'' (Supplement) 60, 71-72.
*Patel, E.R., Coke, C.S., Richie, A., & Santorelli, C. (2003b). Assessing production specificity of free-ranging silky sifaka (''Propithecus candidus'') “anti-predator” vocalizations: weak evidence for “aerial predator” but not “terrestrial predator” calls (Abstract). ''American Journal of Primatology'' (Supplement) 60, 71-72.
*Ritchie, A., & Patel, E. R. (2006). The Existence and Potential Function of “Totem-Tree” Scent-Marking in Silky Sifakas (''Propitheucs candidus''). ''International Journal of Primatology'' (Supplement), 27, 373-4.
*Santorelli, C. J., Parathian, H. E., & Patel, E. R. (2006). Silky Sifaka (''Propithecus candidus'') Ranging, Activity Budget and Demography. ''International Journal of Primatology'' (Supplement), 27, 322-3.

[[Category:Prosimians]]
[[Category:Prosimians]]

Revision as of 01:20, 3 May 2008

Silky Sifaka[1]
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Order:
Primates
Family:
Indriidae
Genus:
Propithecus
Species:
P. candidus
Binomial name
Propithecus candidus
A. Grandidier, 1871

The Silky Sifaka (P. candidus) is a white, diurnal rainforest sifaka found solely within a small area of northeastern Madagascar. It is highly social, patchily distributed, and found at low densities.[3]. 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.[4] The Silky Sifaka is intermediate in size between the Diademed Sifaka P. diadema and Perrier's Sifaka P. perrieri.[5] 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.[4] 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.[3] Marojejy is considered the northern limit of its distribution, with the Antainambalana River as the southern limit.[4] The maximum vertical elevation of the primate (525 meters) was found to exceed other sifakas.[6] Home range size can exceed 40 ha.[7]

Behaviour

The primate's diet is highly folivorous, eating both mature and young leaves, as well as fruit, flowers, seeds, bark, soil, and roots.[3] 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.[8] 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.

The first long-term study (14.5 months) of the silky sifaka examined ranging, activity budget, and demography in Marojejy National Park.[6] 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.

The social structure of the primate is variable, both pair-living and polygynandrous.[7] 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.[6] Group sizes vary from 2 to 9 individuals.[7]

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).[8]

Silky Sifaka mating occurs for only a few days each year between November and January, and young are born in June or July.[9] The primate's litter size is always one, while the inter-birth interval for females is generally two years.[6] 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.[9]

The repeated scent-marking of a tree is referred to as "totem-tree marking".[10] 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.[11] Research has determined that these totem-trees are not territory demarcations but instead are a sign of intra-sexual male competition for females.[10]

Aside from human beings, the only natural predator of the silky sifaka is the fossa (‘’Cryptoprocta ferox’’), an animal particularly adept at eating lemurs.[12] 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.[13]

Conservation issues

The remaining population of the Silky Sifaka is estimated to be as low as a few hundred individuals.[4] In 1994, the IUCN Red List assessment listed P. diadema candidus as Critically Endangered [CR A2cd, B1 + 2bc].[2] Since this assessment has not been updated for over a decade, the primate's category should now be considered [CR C1 + 2a(i)].[4]

The primary conservation threat appears to be hunting and habitat disturbance. It is hunted by locals for delicacy food,[14] as there is no local fady (or taboo) against eating the species.[13] 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.[3]

Local villages adjacent to its remaining protected areas adopted a two-pronged strategy towards Silky Sifaka conservation education.[14] 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 3-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".[14]

Efforts are underway to expand Anjananharibe-Sud Special Reserve and to link existing parks and reserves through protection of continuous forest "corridors".[15] 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[15]

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.[16]

References

  1. ^ 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. (2004). "Specific Status of Propithecus spp". International Journal of Primatology. 25 (4): 875–900. doi:10.1023/B:IJOP.0000029127.31190.e9. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  2. ^ a b Template:IUCN2007
  3. ^ a b c d Mittermeier, R. A., Ratsimbazafy, J., Rylands, A. B., Williamson, L., Oates, J. F., & Mbora, D. (2007). "Primates in Peril: The World's 25 Most Endangered Primates, 2006-2008". Primate Conservation. 22: 1–40.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ^ a b c d e Mittermeier, R. A., Konstant, W. R., Hawkins, F., Louis Jr., E. E., Langrand, O., Ratsimbazafy, J.; et al. (2006). Lemurs of Madagascar. Tropical Field Guide Series (2nd edition ed.). Washington DC: Conservation International. {{cite book}}: |edition= has extra text (help); Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  5. ^ Lehman, S. M., Mayor, M., & Wright, P. C. (2005). "Ecogeographic size variations in sifakas: A test of the resource seasonality and resource quality hypotheses". American Journal of Primatology. 126 (3): 318–28.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ^ a b c d Santorelli, C. J., Parathian, H. E., & Patel, E. R. (2006). "Silky Sifaka (Propithecus candidus) Ranging, Activity Budget and Demography". International Journal of Primatology. 27 (Supplement): 322–3.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ a b c Patel, E. R. (2006a). "Activity budget, ranging, and group size in silky sifakas (Propithecus candidus)". Lemur News. 11: 42–45.
  8. ^ a b Kelley, E., & Mayor, M.I. (2002). "Preliminary study of the silky sifaka (Propithecus diadema candidus) in northeast Madagascar". Lemur News. 7: 16–18.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. ^ a b Patel, E.R., Coke, C.S., Richie, A., & Santorelli, C. (2003a). "Alloparental care (including allonursing) in free ranging silky sifakas (Propithecus diadema candidus) in primary noretheastern montane rain forest in Madagascar". American Journal of Primatology. 60 (Supplement): 71–72.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. ^ a b Ritchie, A., & Patel, E. R. (2006). "The Existence and Potential Function of "Totem-Tree" Scent-Marking in Silky Sifakas (Propitheucs candidus)". International Journal of Primatology. 27 (Supplement): 373–4.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ Patel, E. R. (2006c). "Scent-Marking in Wild Silky Sifakas (Propithecus candidus) in Madagascar: Sex Differences and Seasonal Effects in Usage and Response Across Multiple Scent-Mark Types". International Journal of Primatology. 27 (Supplement): 484–5.
  12. ^ Patel, E.R. (2005). "Silky sifaka (Propithecus candidus) predation by a fossa (Cryptoprocta ferox)". Lemur News. 10: 25–27.
  13. ^ a b Patel, E.R., Coke, C.S., Richie, A., & Santorelli, C. (2003b). "Assessing production specificity of free-ranging silky sifaka (Propithecus candidus) "anti-predator" vocalizations: weak evidence for "aerial predator" but not "terrestrial predator" calls (Abstract)". American Journal of Primatology. 60 (Supplement): 71–72.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  14. ^ a b c Patel, E. R. (2006b). "Appealing to Hearts and Minds: Silky Sifaka (Propithecus candidus) Conservation Education in North-Eastern Madagascar". American Journal of Primatology. 68 (Supplement): 87.
  15. ^ a b The Lemurs of Marojejy and Anjananharibe-Sud (Brochure ed.). Madagascar: Marojejy National Park. 2007.
  16. ^ "Conservation of Lemurs in the Marojejy-Tsaratanana Corridor". World Wide Fund for Nature. 2006. Retrieved 2008-04-14.
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