Silky Sifaka, Propithecus candidus - Top 25 Most Endangered Primates

Image © 2007 by Erik Patel. Silky Sifaka
Propithecus candidus Grandidier, 1871
Madagascar
(2000, 2002, 2004, 2006)
The flagship species of a newly proposed World Heritage Park, silky sifakas are popular with ecotourists, but they are heavily hunted and only a few hundred may remain.

Propithecus candidus is a large, white, rainforest sifaka found only within a small section of northeastern Madagascar. Surveys for these highly social diurnal indriids suggest that they are patchily distributed and occur at low densities within just a few protected areas: Marojejy National Park, Anjanaharibe-Sud Special Reserve, and (very rarely) the Anjanaharibe and Manandriana portions of Makira Protected Area north of the Antainambalana River.
They have been observed primarily in undisturbed forest (except for the Betaolana Corridor) between 700 m and 1,875 m above sea level (Tattersall 1982; Duckworth et al. 1995; Schmid and Smolker 1998; Sterling and McFadden 2000; Goodman et al. 2003; Rakotondratsimba et al. 2007). The behavior and ecology of this species is known mainly from a short study (Kelley and Mayor 2002) and a 14.5-month study at Marojejy National Park (Patel et al. 2005; Patel 2005, 2006, 2007, submitted).
The silky sifaka’s diet is highly folivorous, including mature and young leaves. They also eat fruit, flowers, seeds, bark, soil, and roots. Silky sifakas are the flagship species of a newly proposed World Heritage Site (Marojejy National Park) and are the species that most tourists come to view. Their social structure appears variable (pair-living and polygynandrous), with group sizes ranging from 2 to 9 individuals. Home ranges can exceed 40 ha (Patel 2006). They inhabit several types of elevation-specific habitats including primary montane rainforest, sclerophyllous forest, and even low ericoid bush at their highest elevations (Goodman 2000).
Their primary conservation threat appears to be hunting (Patel et al. 2005). Habitat disturbance, such as slash-and-burn agriculture (‘tavy’), logging of precious woods (for example, rosewood) and fuel-wood, also occurs within and adjacent to the protected areas where they are found (Patel submitted). The remaining population may be as low as a few hundred individuals and is unlikely to be larger than a few thousand (Mittermeier et al. 2006).

Erik R. Patel, David Meyers & Frank Hawkins

References
Duckworth, J. W., M. I. Evans, A. F. A. Hawkins, B. J. Stafford and R. J. Wilkinson. 1995. The lemurs of Marojejy Strict Reserve, Madagascar: a status overview with notes on ecology and threats. Int. J. Primatol. 16: 545–559.
Garbutt, N. 1999. Mammals of Madagascar. Yale University Press, New Haven.
Garbutt, N. 2007. Mammals of Madagascar: A Complete Guide. A&C Black Publishers Ltd., London.
Goodman, S.M. 2000.. Description of the Parc National de Marojejy, Madagascar, and the 1996 Biological Inventory of the Reserve. Fieldiana Zool., new series 97: 1–18.
Goodman, S. M., M. J. Raherilalao, D. Rakotomalala, D., A. Raselimanana, H. Schütz and V. Soarimalala. 2003. Les Lémuriens. In: Nouveaux Résultats d’Inventaires Biologiques Faisant Référence à l’Altitude dans la Région des Massifs Montagneux de Marojejy et d’Anjanaharibe-Sud, S. M. Goodman and L. Wilmé (eds.), pp.279–286. Recherches pour le Développement, série sciences biologiques no. 19, Centre d’Information et de Documentation Scientifique et Technique, Antananarivo.
Kelley, E. and Mayor, M. I. 2002. Preliminary study of the silky sifaka (Propithecus diadema candidus) in northeast Madagascar. Lemur News (7): 16–18.
Mittermeier, R. A., W. R. Konstant, F. Hawkins, E. E. Louis Jr., O. Langrand, J. Ratsimbazafy, R. Rasoloarison, J. U. Ganzhorn, S. Rajaobelina., I. Tattersall, I. and D. M. Meyers. 2006. Lemurs of Madagascar. 2nd edition. Tropical Field Guide Series, Conservation International, Washington DC.
Patel, E. R., J. J. Marshall and H. Parathian. 2005. Silky sifaka (Propithecus candidus) conservation education in northeastern Madagascar. Lab. Prim. Newsl. 44(3): 8–11.
Patel, E. R. 2005. Silky sifaka (Propithecus candidus) predation by a fossa (Cryptoprocta ferox). Lemur News (10): 25–27.
Patel, E. R. 2006. Activity budget, ranging, and group size in silky sifakas (Propithecus candidus). Lemur News (11): 42 – 45.
Patel, E. R. 2007. Non-maternal infant care in wild silky sifakas (Propithecus candidus). Lemur News (12). In press.
Patel, E. R. Submitted. Logging of rare rosewood and palisandre (Dalbergia spp.) within Marojejy National Park, Madagascar.
Rakotondratsimba, J. G., D. Rasolofoson, O. Rakotonirainy and J. Ratsimbazafy. 2007. Le bloc forestier de Makira charnière de lémuriens. Lemur News (12). In press.
Schmid, J. and R. Smolker. 1998. Lemurs of the Reserve Special d’Anjanaharibe-Sud, Madagascar. Fieldiana Zool., new series 90: 227–240.
Sterling, E. and K. McFadden. 2000. Rapid census of lemur populations in Parc National de Marojejy, Madagascar. Fieldiana Zool., new series 97: 265–274.
Tattersall, I. 1982. The Primates of Madagascar. Columbia University Press, New York.

Suggested citation:
Patel, E. R., Meyers, D. and Hawkins, F. 2007. Silky Sifaka, Propithecus candidus. In: Primates in Peril: The World’s 25 Most Endangered Primates 2006–2008, R. A. Mittermeier et al. (compilers), p.6. Unpublished report, IUCN/SSC Primate Specialist Group (PSG), International Primatological Society (IPS), and Conservation International (CI), Arlington, VA.