Indonesian Primates at Risk

Analysis of the relative endangered statuses of a group of Indonesian primates


Our tutor group eliminated Tarsius dentatus and Eulemur coronatus as being at lower risk, so I have considered the three remaining species below, in terms of the vulnerability of the species (including IUCN status, population, geographical range and reasons for decline) and the phylogenetic value of the species (length of evolutionary isolation of genus, number of other species in genus, and vulnerability of these other species):

Golden lion tamarin

Leontopithecus rosalia: the golden lion tamarin’s IUCN Red List status is Endangered (IUCN Red List, 2012). Wild population stands at a mere 1000+, and human deforestation has cut its range to a fragmented 5000km2, but long-term conservation efforts have led the IUCN to downgrade its status from Critically Endangered. Its IUCN Population Trend is Stable.

The genus Leontopithecus has been isolated from others in the Parvorder Platyrrhini for an intermediate period of evolutionary time (Tree of Life Web Project, 2012). Of the other three species in Leontopithecus, two are classed as Endangered and one as Critically Endangered.

Celebes crested macaque

Macaca nigra: the Celebes crested macaque is listed as Critically Endangered on the IUCN Red List, with a Decreasing Population Trend. Discounting an introduced population elsewhere, in recent generations its indigenous numbers have been reduced by 80% due to human habitat encroachment and hunting (as a pest and for bushmeat), and are now estimated at 4000-6000 (Primate Info Net, 2012).

The genus Macaca is of high overall phylogenetic value, for it has evolved in isolation longer than any other genus within the family Cercopithecidae – but Macaca is the most widespread primate genus other than humans, and contains 22 species, of which 7 are considered of Least Concern or Near Threatened.

Sumatran orangutan

Pongo abelii: Our tutor group has identified the Sumatran orangutan as being of the highest priority for conservation. To compare it to the other two species:

Pongo abelii can be considered of greater conservation need than Leontopithecus rosalia because the IUCN give it a worse Red List Status (Critically Endangered) and a worse Population Trend (Decreasing). Its numbers have fallen by over 80% in the last 75 years, to around 7,300, and most individuals live in areas of high risk of logging and forest encroachment. Moreover, being highly arboreal, Sumatran orangutans seem even more vulnerable to habitat fragmentation than their more ground-venturing Bornean relatives.

The genus Pongo is of greater phylogenetic value than Leontopithecus because it has been isolated for longer, there are only two species within it (rather than four), and both are considered Critically Endangered (as opposed to three Endangered and one Critically Endangered).

Although it scores the same IUCN Red List Status and Population Trend as Macaca nigra, Pongo abelii can as a species be considered of higher risk because although the population figures quoted above are comparable, Pongo abelii’s native range is more fragmented than that of Macaca nigra. (Macaca nigra also has an introduced population elsewhere of 100,000 which could be called on as a breeding resource.)

Pongo abelii can also be considered of greater conservation need because of its higher phylogenetic value and risk. The genera Pongo and Macaca have both evolved in long isolation, but Pongo numbers but two species, both Critically Endangered and of severely depleted and decreasing habitat ranges (as opposed to Macaca with 22 species, several of low concern, and with a very large overall habitat range).


IUCN Red List 2012, Leontopithecus rosalia, available from (Accessed 18 February 2012)

IUCN Red List 2012, Macaca nigra, available from (Accessed 18 February 2012)

IUCN Red List 2012, Pongo abelii, available from (Accessed 18 February 2012)

Tree of Life Web Project 2012, Platyrrhini, available from (Accessed 18 February 2012)

Tree of Life Web Project 2012, Cercopithecidae, available from (Accessed 18 February 2012)

Tree of Life Web Project 2012, Hominidae, available from (Accessed 18 February 2012)

Primate Info Net 2012, Macaca nigra, available from (Accessed 18 February 2012)

Article for OU Module S104 Exploring Science © Andrew Murray 2012


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s