All sifakas are amazing leapers, jumping distances of up to thirty feet. When on the ground, they move by leaping sideways on their hind limbs.
Neither P. diadema candidus and P. diadema perrieri have been formally studied, and therefore little is known of their ecology and behavior. They are both extremely rare, and so time is running out to find out about these creatures (Garbutt, 1999).
Strangely enough, leaping primates (including sifakas), do not take adavantage of the elasticity of the substrates on which they move. Therefore, unlike most things in nature, leaping locomotion is not an evolutionarily efficient locomotory strategy for large-bodied primates (Demes, 1995).
As in all primate species, communication is rich and varied. Vocalizations are used mainly in maintaining group cohesion. Two alarm vocalizations are given in response to predators. The ground predator call is a "tzisk-tzisk-tzisk", and the aerial predator call is a "honk-honk-honk" (Wright, 1988, 1995; Garbutt, 1999; Mittermeier, 1994).
Scent marking is common, and males scent mark twice as often as females. Scent marking frequency doubles when approaching the territorial boundaries (Wright, 1988, 1995; Garbutt, 1999; Mittermeier, 1994).
In addition to vocal and chemical communication, these animals use tactile communication, in the form of grooming, play, and aggression. Tactile communication is likely to be of high importance between mothers and their offspring, as well as between mates.
Although not specifically reported for these animals, we may assume that, like other diurnal primates, they use visual signals in their communication also. These include but are not limited to facial expressions and body postures (Nowak, 1999).
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Both P. diadema candidus and P. diadema perrieri are given IUCN critically endangered status. All subspecies are threatened by habitat destruction. This occurs mainly in the form of slash-and-burn agriculture, but also as timber extraction. Most are also hunted for food, even in protected areas. All subspecies occur in at least one protected area.
In response to these threats, several reserves have been established within the last few decades. Also, campaigns to educate locals and find better methods of agriculture have been persued (Wright, 1992; Mittermeier, 1994; Garbutt, 1999).
US Federal List: endangered
CITES: appendix i
IUCN Red List of Threatened Species: endangered
There is no known negative economic effect of this species on humans.
The existence of this rare and endemic species, as well as the rest of Madagascar's unique flora and fauna, has stimulated a large amount of ecotourism for the area. This, along with the establishment of several reserves in Madagascar's remaining forests, has helped to bolster the economy of a severely depressed nation (Wright, 1992).
Positive Impacts: ecotourism
As frugivores, these animals probably help to disperse seeds. As potential prey items, they may impact predator populations.
Ecosystem Impact: disperses seeds
Propithecus diadema is herbivorous, eating only leaves, flowers, fruits, and young shoots. Approximately 25 species of plants are consumed in each of the two subspecies that have been studied (P. diadema edwardsi and P. diadema diadema). Propithecus diadema edwardsi has also been seen eating soil, possibly to detoxify plant poisons or to supplement their diet with trace elements (Garbutt, 1999).
Plant Foods: leaves; fruit; flowers
Primary Diet: herbivore (Folivore , Frugivore )
Propithecus diadema, like all lemurs, occurs only in Madagascar. Although all sifakas occur on the eastern side of the island, each of the four described subspecies has a distinct range (Garbutt, 1999).
Biogeographic Regions: ethiopian (Native )
Other Geographic Terms: island endemic
Sifakas generally inhabit mid-altitude rainforests. These animals mainly occur at elevations above 800 meters. The range of P. diadema candidus extends into montane rainforest. Rainfall in sifaka habitat is variable, from 2000 to 4000 mm per year, with most rainfall occurring during the summer months (December through March) (Wright, 1995; Garbutt, 1999).
Range elevation: 800 (low) m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: rainforest ; mountains
The longevity of this species has not been reported. However, an individual of another species in the genus, Propithecus verreauxi, is reported to have lived beyon 23 years on captivity (Nowak, 1999). It is likely that P. diadema is capable of reaching similar ages.
Members of the genus Propithecus reach lengths between 450 and 550 mm, with the tail adding an additional 432 to 560 mm. Propithecus diadema weighs between 5 and 7 kg.
Each subspecies is phenotypically unique. Propithecus diadema diadema is often reported to be the largest extant lemur. These animals have a white head, grey shoulders, tail, and back, and golden limbs. Propithecus diadema edwardsi is almost completely grey/black, with a white back. Propithecus diadema candidus has almost completely white pelage with tints of grey. Propithecus diadema perrieri is completely black. All subspecies have dark naked faces and red-orange eyes.
The only other animals with which these animals might be confused are indris. However, sifakas have a very long tail, which distinguishes them from short-tailed indris.
Range mass: 5 to 7 kg.
Range length: 450 to 550 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Individuals of all ages and both sexes are subject to predation. No documented cases of predation by reptiles or raptors exist, but suspected avian predators include Madagascar harrier-hawks and Henst's goshawks. The main predators of P. diadema are probably fossas, an ambush predator that takes advantage of any opportunities available.
Two alarm vocalizations are given in response to predators. The ground predator call is a "tzisk-tzisk-tzisk", and the aerial predator call is a "honk-honk-honk" (Wright, 1988, 1995; Garbutt, 1999; Mittermeier, 1994).
Known Predators:
Our current understanding of the mating system of this species is limited. Mating occurs between resident males and resident females, with no recorded cases of invading males successfully copulating. There is a hierarchy system for mating, and it seems that only the dominant male copulates with the females. Submissive males may show aggression and attempt to keep the dominant male from mating.
Mating System: polygynous
The best data on reproduction exists for P. diadema edwardsi, but data for other subspecies suggest that they are similar. Copulations occur in summer, in the months of December and January. Gestation period is around 180 days (approximately six months). Females give birth to one or two offspring in the winter months (May, June, July).
Offspring are carried by their mother. The young may nurse up to the age of 2, although by this time, mother's milk does not provide them with a substantial amount of their nutrition. Sexual maturity is reached at four years for females and five years for males. Birth rates are approximately 0.5 offspring per female per year (Wright, 1995; Garbutt, 1999).
Breeding interval: Females are able to produce offspring every two years.
Breeding season: Copulations occur in summer, in the months of December and January
Range number of offspring: 1 to 2.
Average gestation period: 180 days.
Range weaning age: 24 (high) months.
Average age at sexual or reproductive maturity (female): 4 years.
Average age at sexual or reproductive maturity (male): 5 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous
Average birth mass: 145 g.
Average gestation period: 157 days.
Average number of offspring: 1.
Average age at sexual or reproductive maturity (male)
Sex: male: 913 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 1186 days.
Offspring initially cling to the mother's belly, switching to her back at around one month of age. Nursing begins to decrease from the age of two months, although the process of weaning is protracted. At six months of age, less than half of the offspring's diet consists of the mother's milk. At one year of age, suckling during the day ceases. Suckling during the night, however, may continue until the infant is two years old.
In addition to food, the mother provides her young with protection, grooming, and socialization.
The role of males in parental care has not been described.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Protecting: Female); extended period of juvenile learning
