Silky Sifaka - Geographic Range and Habitat

Geographic Range and Habitat

The silky sifaka is confined to a small region of northeastern Madagascar within a strip of humid forest stretching from Maroantsetra 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 (2,300 ft) of elevation and not above 1,875 m (6,152 ft). However, at its southernmost location in Makira (Andaparaty), several groups inhabit forest fragments at an unusually low elevation of 300 m (980 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 unforested 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.