Ang Hui Fang’s Banded Leaf Monkey work in The Straits Times

Monkey species in better shape than thought,” by Victoria Vaughan. The Straits Times, 10 Apr 2010. Study finds number of banded leaf monkeys 3 times greater than previously believed.

NUS’ Andie Ang spent 11/2 years tracking the monkeys. She found, among other things, that their offspring’s definitive colour is white, not orange as reported. — ST PHOTO: NEO XIAOBIN

ONCE feared to be on the brink of extinction, data has surfaced to suggest that Singapore’s banded leaf monkey population is healthy and is, in fact, growing.

A student from the National University of Singapore (NUS) who spent 11/2 years tracking the black monkeys in the Central Catchment Area has concluded that the number is roughly treble of what was previously thought to exist.

The last reliable data, recorded in the 1990s, reported that there were 10 to 15 of these shy tree-dwelling monkeys left in Singapore.

But Miss Andie Ang, 25, has documented evidence to prove that there are at least 40 roaming the MacRitchie and Lower Peirce Reservoir areas. From September 2008, she spent five days a week in the forest to gather data for her master’s biology programme. It took 13 dawn-till-dusk sorties before Miss Ang found the first monkey and she has since seen at least 40 individuals.

By carrying out simultaneous surveys with help from a National Parks Board (NParks) ranger, she could determine that she was seeing different monkeys and, therefore, had a good population count. ‘I was pretty surprised to find 40. I don’t want to stop this work, I hope to see what can be done to stabilise the population,’ she said.

But it is unclear whether the increase in number is because the population is recovering or because previous surveys were not as comprehensive. The data collected, which covers social, breeding and eating habits, will go into Miss Ang’s master’s thesis, to be completed in July and submitted to journals for potential publication.

Associate Professor Rudolf Meier, who is supervising the project, said this was a significant study but it was hard to predict if the number was big enough for the population to recover. ‘There is a genetic bottleneck – the genetic diversity is low,’ he said. This lack of diversity could lead to vulnerability to disease or reproductive problems. ‘Also, the infant mortality rate is extremely high for these monkeys – probably more than 50 per cent.’

Deputy director of the NParks’ National Biodiversity Centre, Dr Lena Chan, said more had to be done to boost future conservation measures. ‘This species has special significance for Singapore as it was first described here in 1838. When we know what it likes to eat, we could look at planting more of those plants,’ she said. She added that the soon-to-be built Eco-Link – set to cross the Bukit Timah Expressway and link Bukit Timah Nature Reserve to the Central Catchment Nature Reserve – could help extend their habitat.

There is also a possibility of using the leaf monkey, believed to be related, from Johor to help increase the genetic pool.

The banded leaf monkey is one of three primate populations here, along with long-tailed macaques, which number about 1,500, and the nocturnal slow loris, the population of which is unknown.

The study was the first to be supported by the Wildlife Reserves Singapore Conservation Fund, which committed $500,000 over five years to NUS’ Ah Meng Memorial Conservation Fund, set up about a year ago to support this kind of work.

One thought on “Ang Hui Fang’s Banded Leaf Monkey work in The Straits Times

  1. Great work! Banded Surilis (?) have been spotted in Bintan Island too. Rare sightings suggest small population there although no known study has been done on this population. If anyone is interested to share info on this primate or would like to study the animals in Bintan Resorts areas, pls write to

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