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Diademed Sifaka - Propithecus diadema
Diademed Sifaka - Propithecus diadema

[Image: 320px-Diademed_sifaka_%28Propithecus_diadema%29.jpg]

Scientific classification
Kingdom:  Animalia
Phylum:  Chordata
Class:  Mammalia
Order:  Primates
Suborder:  Strepsirrhini
Family:  Indriidae
Genus:  Propithecus
Species:  Propithecus diadema  Bennett, 1832

The diademed sifaka (Propithecus diadema), or diademed simpona, is an endangered species of sifaka, one of the lemurs endemic to certain rainforests in eastern Madagascar. Along with the indri, this species is one of the two largest living lemurs, with an average weight of 6.5 kg and a total adult length of approximately 105 centimetres (41 inches), half of which is its tail. Russell Mittermeier, one of the contemporary authorities on lemurs, describes the diademed sifaka as "one of the most colorful and attractive of all the lemurs", having a long and silky coat. P. diademais also known by the Malagasy names simpona, simpony and ankomba joby. The term "diademed sifaka" is also used as a group species designation formerly encompassing four distinct subspecies.

P. diadema is readily distinguished from all the other lemur species by its characteristic markings and large physical size. Its entire coat is moderately long, silky and luxuriant. The long white fur encircling his muzzle and covering its cheeks, forehead and chin, engenders the "diadem" or crown appearance. Its eyes are a reddish brown, the muzzle is short, and the face is bare with colourisation of darkish gray to jet black. The crown fur is also quite black and often extends to the nape of the neck. The upper back and shoulder fur are slate grayish, although the lower back is lighter in colour attaining a silvery quality. Flanks and tail are a paler gray, sometimes even white, as is the case for ventral fur. Hands and feet are entirely black, while arms, legs and base of tail are a yellowish-golden hue. Only the male is endowed with a large cutaneous gland at the exterior center of the throat, which feature is typically reddish brown.

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Range and habitat
The diademed sifaka is one of the mostly widely distributed member of the genus Propithecus, although definitive mapping of its range has not been conducted. Occurrence is at altitudes of 200 to 800 metres (656 to 2,624 feet) throughout much of the eastern Madagascar lowland forests and altitudes 800 to 1,550 metres (2,624 to 5,084 feet); in portions of the Madagascar subhumid forests. These two biomes have been designated as a Global 200 ecoregion, one of the world's most significant regions for conservation. Geographically the range extends to at least the Mananara River in the north to the Onive and Mongoro Rivers in the south. One set of researchers has recorded a clinal variation between Propithecus diadema and Propithecus edwardsi in the extreme southern portion of the range. As with all Indriidae, this species and its entire genus have evolved on the island of Madagascar independent of other mainland African species.
An anomalous outlier population of P. diadema has been discovered in south central Madagascar; the members of this population exhibit an array of different colour markings, including at least one observation of an all black lemur. DNA analyses have not resulted in consistent results as to whether this group of individuals should constitute a new species. Scientists have decided to classify this outlier group as P. diadema until further research warrants designation of a separate species.

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Distribution of P. diadema

Specific locations for sighting the diademed sifaka are Mantadia National Park (approximately three hours in driving time from the capital city of Antananarivo) and in the forests of Tsinjoarivo.

The diademed sifaka forms groups typically of two to ten individuals, which may include multiple male and female adults. Each troop defends an exclusive home territory of 25 to 50 hectares (62 to 125 acres) using perimeter scent territorial marking by both the males and females. Although the diademed sifaka defends the group's territory strongly against other members of their same species, it will share territory with other species such as the Red-bellied Lemur and the common brown lemur. P. diadema is thought to traverse the greatest daily path distance relative to other members of its family in its patrolling and foraging, attaining a typical travel distance in excess of 1.6 kilometres (one mile) per day. To accomplish this it consumes a diet high in energy content and diverse in plant content, each day consuming over 25 different vegetative species. This diurnal lemur further diversifies its diet by consuming not only fruits, but certain flowers, seeds and verdant leaves, in proportions that vary by season.
For a large lemur, the diademed sifaka is rather athletic, being capable of lateral aerial propulsion of up to 30 kilometers per hour, a result of muscular leg thrusting action pushing off from a vertical tree trunk. It is possible, although not proven, that its vigorous health characteristics are enhanced from high consumption of two plants which contain high concentrations of alkaloids. This species is arboreal, and only rarely are seen on the ground; moreover, it is a vertical clinger and lateral leaper.
The diademed sifaka makes a warning call resembling the sound "kiss-sneeze" when a terrestrial predator is perceived; the sole terrestrial predators of P. diadema are the Fossa and Nile Crocodile.
Sexual maturity occurs after age two or three, with the male maturing somewhat more slowly than the female. Little is known of mating behaviour; however, it is believed that the female is receptive to mating only a few days per year. Being dominant, the female has the greatest input to mate selection. Copulation occurs in the summer (around December), and the expected number of births is one offspring per female per annum.

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Conservation issues

The diademed sifaka is classified as critically endangered on the IUCN Red List, and is listed in CITES Appendix I. As of the year 2002, population estimates for the species range between 6,000 and 10,000 individuals. The primary threat is habitat reduction due to shifting cultivation by native peoples. This threat is also present even within designated national parks, which are sufficiently distant from the center of government, that enforcement of existing national laws protecting P. diadema habitat is problematic. Pressures of overpopulation in central and eastern Madagascar are causing many of the rural poor to seek subsistence by seizing whatever forest lands are available and undertaking slash-and-burn tactics as their initial step in a shifting cultivation system. Returns from such land use are usually meager, yielding small amounts of charcoal, firewood or grass crop for grazing of zebu.


The diademed sifaka and three other sifaka species form a tight species group within the genus Propithecus. The other three species are Milne-Edwards' sifaka (Propithecus edwardsi), Perrier's sifaka (P. perrieri), and the silky sifaka (P. candidus). All of these species have luxuriant silky coats and are powerful leapers. They share similar characteristics of gestation length (four months), age of sexual maturity, female dominance, life expectancy (18 years) and propensity for sunbathing while stretched out on a branch. They differ distinctly in colouration and markings, except for having universally totally black faces.

Study finds severely disturbed habitats have impacted health of Madagascar's critically endangered lemurs

by Tom Parisi, Northern Illinois University

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A diademed sifaka lemur in Madagascar’s Tsinjoarivo forest. Credit: Mitch Irwin, Northern Illinois University

A new study led by Mitch Irwin and Karen Samonds of Northern Illinois University finds that degraded rainforest habitats are having an unhealthy impact on at least one species of Madagascar's treasured lemurs, the most endangered mammal group in the world.
Irwin, Samonds and other research team members captured, measured and released 113 critically endangered diademed sifakas over the course of 19 years. They then compared the health of the animals living in intact continuous rainforest versus those in habitats disturbed and fragmented by human encroachment.
Working with a veterinarian to ensure animal safety, the scientists recorded the body mass, length and body condition of the stunning silken-furred primates, which grow to be roughly a meter in length and weigh in at about 6.5 kilograms. The results actually revealed that sifakas in some fragmented rainforest environments were doing fine—their bodies were identical to those animals in the richest environments.
But significant differences were found in the two most disturbed habitats.
"Below a critical threshold in the most degraded of all fragments, there were key differences—adults were skinnier, and the growth of immatures was delayed both in their height and weight," said Irwin, an NIU professor of anthropology and lead author of the study. The study was published June 19 in Scientific Reports, an open access journal of the Nature Research family.
Notably, the 11 lemurs living in the three lowest-quality habitats, representing three separate groups of the animals, died or disappeared during the study duration. The authors said it is unclear whether the habitats will be recolonized.
"Although anecdotal, the loss of these three groups would seem to corroborate the interpretation that their health was impacted by their low-quality habitat," Irwin said. "It's sad to actually witness a species' range shrink—it's a small step toward extinction."
For groups of sifakas in the remaining fragmented areas, both nutritional inputs and body measurements showed little distinction from groups living in optimal continuous forest, despite a noticeable degree of habitat fragmentation and disturbance.
"This suggests substantial resilience to moderate levels of habitat change," Irwin said. "If no further degradation occurs, the remaining long-term viability of groups in these fragmented areas may depend more on whether juveniles can disperse to find new groups than on nutritional inputs. If they are stuck in small isolated fragments they may die out due to inbreeding."
The study also presents the first detailed data on body proportions and dimensions of wild diademed sifakas. The animals are among the largest living lemur varieties, live in groups of two to 10 individuals and have life spans that typically exceed 20 years. Foliage is usually the major component of sifaka diets, although fruits and seeds can play a major role.
"Sifakas are long-lived animals, so they may not rapidly go extinct in these degraded habitats, but over time these threats can add up and cause these populations to be lost," Irwin said. "This research not only helps identify which groups are at risk, but identifies ways to monitor their health directly through these measurements of size and growth."
The study was conducted on sifakas living in Madagascar's Tsinjoarivo forest, part of the newly-created Tsinjoarivo-Ambalaomby protected area. Located 80 kilometers south and southeast of the capital city of Antananarivo, the rainforest is home to many spectacular varieties of lemurs, a group of primates only found in the island country.
Its preservation is being spearheaded by the NGO SADABE, a Malagasy organization created by Irwin and Samonds with Malagasy colleagues. Each year, Irwin and Samonds, a husband-and-wife team of scientists, spend a large portion of their summer conducting research in the region.
Though the Malagasy care deeply for the forest, limited economic options in poor rural areas often lead to uncontrolled and unsustainable natural resource exploitation. Over roughly the past 35 years, much of Tsinjoarivo's forests were turned to agricultural plots and trees chopped down for lumber, disturbing habitats. The rainforest's western half has been fragmented and degraded by settlers, while the eastern half is minimally disturbed.
Many studies have examined how human-caused habitat change can affect wildlife populations. But wild animals, especially highly intelligent primates, are very flexible. "They can change their diet and movement patterns to respond to changing conditions," Irwin said. "You really need direct indicators of health to know if those changes reflect an underlying threat to the population."
Samonds and Irwin continue to collect data this summer.
"For this kind of research, you need a long-term database," said Samonds, an NIU professor of biological sciences. "Basic health parameters such as body size and condition are perhaps the best tools for judging population viability, but getting the measurements typically requires captures, which are often challenging."
Other authors on the new study are Jean-Luc Raharison and Karine Lalaina Mahefarisoa of the nonprofit SADABE Madagascar organization; Randall Junge of the Columbus Zoo and Aquarium in Ohio; Fidisoa Rasambainarivo of Mahallana Labs in Madagascar; Laurie Godfrey of the University of Massachusetts, Amherst; and Kenneth Glander of Duke University.

Journal Reference:
Mitchell T. Irwin et al. Morphometric signals of population decline in diademed sifakas occupying degraded rainforest habitat in Madagascar, Scientific Reports (2019). DOI: 10.1038/s41598-019-45426-2

Anthropogenic habitat change can have varied impacts on primates, including both negative and positive outcomes. Even when behavioural shifts are seen, they may reflect decreased health, or simply behavioural flexibility; understanding this distinction is important for conservation efforts. This study examines habitat-related variation in adult and immature morphometrics among diademed sifakas (Propithecus diadema). We collected morphometric data from sifakas at Tsinjoarivo, Madagascar (19 years, 188 captures, 113 individuals). Captures spanned 12 groups, five within continuous forest (“CONT”), and seven in degraded fragments (“FRAG”) where sifakas have lower nutritional intakes. Few consistent differences were found between CONT and FRAG groups. However, using home range quality as a covariate rather than a CONT/FRAG dichotomy revealed a threshold: the two FRAG groups in the lowest-quality habitat showed low adult mass and condition (wasting), and low immature mass and length (stunting). Though less-disturbed fragments apparently provide viable habitat, we suggest the sifakas in the most challenging habitats cannot evolve fast enough to keep up with such rapid habitat change. We suggest other long-lived organisms will show similar morphometric “warning signs” (wasting in adults, stunting in immatures); selected morphometric variables can thus be useful at gauging vulnerability of populations in the face of anthropogenic change.
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