Propithecus deckenii Peters, 1870

Scientific name:

Propithecus deckenii

Scientist name:

Peters, 1870

Malagasy:

Sifaka, Tsibahaka

English:

Decken’s Sifaka

German:

Von der Decken’s Sifaka

French:

Propithèque de von der Decken

Family:

INDRIIDAE Burnett, 1828

Taxa:

Propithecus

Species

Identification

Propithecus deckenii is a medium-sized, white sifaka from western Madagascar. It has a head-body length of 42–48 cm, a tail length of 50–60 cm, a total length of 92–110 cm, and a weight of 3.0–4.5 kg (Tattersall, 1982). The dorsal coat is creamy-white with tints varying from gold to pale brown on the neck, shoulders, back and limbs. The face is black, but usually with a patch of white fur running across it. Bony pockets on either side of the muzzle give this animal a rather blunt-nosed appearance, but not as extreme as in the crowned sifaka (Propithecus coronatus).

Decken’s sifaka is easy to distinguish from other lemurs within its range except for P. coronatus, with which it may partially overlap in limited areas. Propithecus coronatus is also predominantly white, but has a distinctive dark brown to black hood, extending onto the shoulders. It has a very distinct and unusual bulbous nose.

Natural history

This species has not yet been studied in the wild. We know only that it is diurnal, inhabits dry deciduous forests, lives in groups of 6–10 individuals, and can survive in degraded habitat, sometimes even appearing in Eucalyptus trees in the middle of the town of Soalala (F. Hawkins, pers. obs.).

Geographic range

This sifaka is found in patches of highly fragmented
deciduous forest in western Madagascar between the
Mahavavy and Manambolo rivers (Petter et al., 1977;
Tattersall, 1982, 1986; Thalmann and Rakotoarison,
1994). The southern limit of its range does not extend to
the Tsiribihina River, which marks the northern limit for
Propithecus verreauxi. To the north, in the coastal forests
that occur between the Mahavavy and Betsiboka rivers, the
geographic separation between P. deckenii and P. coronatus
appears clear. However, in the lower reaches of the Mahavavy
River, populations of the two species apparently hybridize,
and there are individuals with intermediate coloration on
islands in the middle of the Mahavavy (Thalmann et al.,
2002). More confusing is the situation in forests of the
Bongolava Massif, far inland and to the southeast, where
animals with color patterns characteristic of both species have
been observed (Petter and Peyriéras, 1972). Furthermore,
according to recent surveys, populations representing both
species can be found at a number of sites (Randrianarisoa et al., 2001; Thalmann et al., 2002).

Needless to say, the taxonomic status of these two forms and their relationship to one another require further investigation, especially in the field. However, for now, we continue to recognize them as distinct species.

Conservation status

The 2008 IUCN Red List assessment classified P. deckenii as Vulnerable (VU). Forests in its range are already highly fragmented, and continued habitat loss is the greatest threat to its survival. Forests are burned to provide pasture for livestock and cut for charcoal production. The animal itself is protected by a very strong taboo in much of its range, becoming very tame as a result, but if the taboo were to break down for whatever reason the species could disappear very rapidly.

Decken’s sifaka occurs in three national parks (Baie de Baly, Tsingy de Bemaraha, and Tsingy de Namoroka), the Tsingy de Bemaraha Strict Nature Reserve, four special reserves (Ambohijanahary, Bemarivo, Kasijy, and Maningoza), and in at least one classified forest (Tsiombikibo) (Nicoll and Langrand, 1989; Hawkins et al., 1998; Garbutt, 2007; Thalmann et al., 1999, 2002; Randrianasoa et al., 2000; J. Durbin, pers. comm.; E. E. Louis Jr., pers. obs.).

As of 2010, this species was not being kept in captivity (I. J. Porton, pers. comm.).

Where to see it

The best place to see this species in the wild is the Tsingy de Bemaraha National Park, where it can be observed easily along the main tourist routes. It can also be observed in the Tsiombikibo Classified Forest northwest of Mitsinjo, about four hour’s drive from Katsepy (Garbutt, 2007), and in forests in and near Soalala and on both sides of the Baie de Baly.

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