Propithecus edwardsi, Grandidier, 1871

Russell A. Mittermeier, Anthony B. Rylands & Don E. Wilson, 2013, Indriidae, Handbook of the Mammals of the World – Volume 3 Primates, Barcelona: Lynx Edicions, pp. 142-175 : 172

16.

Milne-Edwards’s Sifaka

Propithecus edwardsi

French: Sifaka de Milne-Edwards / German: Milne-Edwards-Sifaka / Spanish: Sifaca de Milne-Edwards

Other common names: Milne-Edwards’s Simpona

Taxonomy. Propithecus edwardsi Grandidier, 1871 ,

Madagascar, west of Mananjary.

There appears to be a clinal gradient between this species and P. diadema . There are apparent intermediates between P. diadema and P. edwards: at Anosiben’Ifody on the left bank of the upper Mangoro River, whereas typical P. edwards: occurs further south along this river where it turns east toward the sea. The melanistic variant (holomelas), long recognized as a subspecies of P. diadema , is now generally considered synonymous with this species. Almost entirely black except for a dark brown patch at the base of the tail, and perhaps slightly smaller in size on average than typical P. edwards, it was formerly found in the forests of Nandihizana, apparently in groups of normally colored P. edwardsi . Unfortunately, sifakas are now gone from this region, and no similarly colored animals have been found elsewhere, making it difficult to determine whether or not it was indeed a distinct taxon. Monotypic.

Distribution. CE Madagascar, the Mangoro and Onive rivers are the N limits of the present range, and the Rienana River in Andringitra National Park is the S boundary. The former distribution probably extended somewhat N and further S to the Manampatrana River, but populations in those regions appear to have been extirpated.

Descriptive notes. Head-body 42-52 cm,tail 41-48 cm; weight 5-5 kg. Milne-Edwards’s Sifaka is a large, heavily built species of Propithecus . The dorsal coat is dense and dark, varying from chocolate-brown to almostjet-black on the head, upper body, limbs, and tail. Bilateral whitish patches of varying extent grade into the darker surrounding fur on the back and flanks, sometimes meeting along the spine. The ventral coat is equally dark, sometimes paler around the upper part of the chest, but itis less dense than the dorsal coat. The face and ears are bare, and the skin is dark gray to black, with the ears barely discernible above the dark fur of the head. Eyes are orange-red. Juveniles resemble adults.

Habitat. Primary and slightly degraded secondary rainforest at middle to high elevations of 600-1600 m.

Food and Feeding. Diets of Milne-Edwards’s Sifaka consist mainly of young leaves, ripe fruits, seeds, and flowers, but they also eat some mature leaves, bark, subterranean fungus, and soil. About a dozen different plant species are sampled each day. Dietary composition appears to vary significantly, however, not only from month to month but also from year to year.

Breeding. Copulations of Milne-Edwards’s Sifaka only occur over a single 24hour period when the female is in estrus and fertile, but females within a group are fertile on different days. Fertility is signaled by about a ten-hour long, externally visible pink genital swelling. Males’ testicles enlarge as the breeding season nears. Copulation is brief (often only 30-90 seconds) and consists of a single mount. A single young is born in June-July, after about a six-month gestation (average 179 days). Births in a group tend to be synchronous, with six of eight births in one study occurring during just one week. Average birth weight is 156 g. Infants transfer from their mother’s belly to her back after about 3-4 weeks, riding comfortably there at about two months of age. At night, mothers continue to sleep with their offspring until they are about two years old. Allogrooming and self-grooming commence in the fourth week of life. Play starts by week six and most often occurs between the infant and a juvenile. The infant spends more time on its mother than on any other group member, and the mother is the main care provider. By one year, juveniles weigh 2-5 kg. Predation, especially by the Fosa (Cryptoprocta ferox), is a significant cause of death in infants. Infant mortality is high, with over one-half of female infants dying in their first year of life and only one-quarter surviving to reproductive age. Infanticide has been well documented in Milne-Edwards’s Sifaka, particularly by unrelated adult male sifakas, which may serve as a male strategy to induce heat in females and shorten the interbirth interval from c.1-5 years (typical of mothers with infants surviving one year). Mothers wean their offspring six months after birth, which corresponds to just slightly before the subsequent breeding season. Age at first birth for females is about four years old, with an increase in fertility at six years. Males reach reproductive maturity at five years. About one-half of male and female Milne-Edwards’s Sifakas emigrate from their natal group, with females leaving before maturity and males both before and after maturity. One individual reached an age of 27 years.

Activity patterns. There is no specific information available for this species, but Milne-Edwards's Sifaka is diurnal and arboreal.

Movements, Home range and Social organization. Field studies of Milne-Edwards’s Sifakas have been carried out at Ranomafana National Park. It lives in multimale— multifemale groups of 3-9 individuals, typically containing 1-3 adult females and 1-2 adult males, and only one breeding pair. Females are dominant to males. Home range size is 40-250 ha. Exclusive territories are maintained, although there is little aggression over boundaries. Mean daily path of movement averages 670 m. Males emigrate at age five to a neighboring group; females may either emigrate or remain in their natal group. Milne-Edwards’s Sifaka populations can have polygynous, polygynandrous, polyandrous, and monogamous mating systems. Density at Ranomafana is relatively low at 7-6 ind/km?, with densities in healthy populations south of the park reportedly even lower at ¢.3 ind/km?.

Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List. However, at the IUCN/SSC Lemur Red-Listing Workshop in July 2012, P. edwards: was assessed as critically endangered. Habitat destruction for slash-and-burn agriculture, logging, and gold mining are the main threats to Milne-Edwards’s Sifakas. These activities sometimes take place even in protected areas. Hunting is also a problem, with shotguns, blowguns, and slingshots used as the primary weapons. Milne-Edwards’s Sifaka occurs in two national parks (Andringitra and Ranomafana), and it also may be found in Andohahela National Park and Pic d’Ivohibe Special Reserve. There are populations in the unprotected forests north of Ranomafana and a number of unsurveyed forest reserves in eastern Fianarantsoa Province. The total world population is estimated at 9000 individuals, with ¢.4500 in Ranomafana.

Bibliography. Andriaholinirina et al. (2004), Dunham et al. (2008), Erhart & Overdorff (1998), Feistner & Schmid (1999), Glanderet al. (1992), Grieser (1992), Groves (2001), Groves & Helgen (2007), Hemingway (1995, 1996, 1998, 1999), Irwin, Johnson & Wright (2005), Irwin, Smith & Wright (2000), Lehman & Wright (2000), Lehman, Mayor & Wright (2005), Lehman, Ratsimbazafy et al. (2006), Meyers (1993), Meyers & Wright (1993), Mittermeier, Konstant et al. (2006), Mittermeier, Langrand et al. (2010), Mittermeier, Tattersall et al. (1994), Nicoll & Langrand (1989), O'Connor et al. (1986, 1987), Pochron & Wright (2002, 2003, 2005), Pochron, Fitzgerald et al. (2003), Pochron, Morelli, Scirbona & Wright (2005), Pochron, Morelli, Terranova et al. (2005), Pochron, Tucker & Wright (2004), Pochron, Wright et al. (2002), Sterling & Ramaroson (1996), Tan & Wright (1995), Tattersall (1982, 1986a, 1986b), Wright (1995, 1998), Wright, Daniels et al. (1987), Wright, Heckscher & Dunham (1997).

Figures

On following pages: 12. Crowned Sifaka (Propithecus coronatus); 13. Coquerel’s Sifaka (Propithecus coquerell); 14. Tattersall’s Sifaka (Propithecus tattersall); 15. Diademed Sifaka (Propithecus diadema); 16. Milne-Edwards's Sifaka (Propithecus edwardsi); 17. Silky Sifaka (Propithecus candidus); 18. Perrier’s Sifaka (Propithecus perrieri).

Distribution. CE Madagascar, the Mangoro and Onive rivers are the N limits of the present range, and the Rienana River in Andringitra National Park is the S boundary. The former distribution probably extended somewhat N and further S to the Manampatrana River, but populations in those regions appear to have been extirpated.