Highly endangered Raffles’ Banded Langur population in Singapore to double in 15 years
New research shows the population of Raffles’ Banded Langurs is projected to grow from 75 to over 150 in the next 15 years, and reach around 244 by 2071.
SINGAPORE - The critically endangered Raffles’ Banded Langur, once thought to be on the brink of extinction in Singapore, is now projected to have a population of around 244 by 2071.
This contradicts earlier research conducted in the 1990s, which had indicated a high likelihood of extinction for the species within 40 years due to habitat loss and fragmentation.
The new projections, based on model calculations by researchers from Singapore and the Oxford Brookes University in the United Kingdom, show the population of the endangered monkeys is projected to double, from 75 to over 150, in the next 15 years.
The findings emerged in a recent paper published in the Raffles Bulletin of Zoology in September, a joint media release on Tuesday (10 October) by Mandai Nature and Oxford Brookes University said.
Loss of unprotected habitat is greatest threat presently
Based on results from an ecological software, the research team found that the "greatest current threat" to the Raffles’ Banded Langur population in Singapore is the "loss of unprotected habitat".
To effectively manage its population size, forest fragments, in which the langurs live in, must be better connected, the team said.
Despite positive study results, the researchers also warned that a slight increase in deaths could lead to a reduction in population size within the next 50 years.
Langurs vulnerable to road accidents, diseases and extreme weather
While the research paper projects that the Raffles’ Banded Langur population is likely to continue growing in the next 50 years, the species remains vulnerable to deaths from roadkill and unpredictable events, such as diseases and extreme weather, said Amy Woolloff, the paper’s lead author.
Road accidents occur when the langurs attempt to cross busy roads between forested areas, Woolloff said.
From 2017 and 2023, four Raffles’ Banded Langurs — roughly five per cent of the total population in Singapore — died from road vehicle collisions.
For the species to survive in Singapore, Woolloff said, more suitable habitats for the langurs must be identified, with improved habitat connectivity to prevent road crossing deaths.
Increasing the genetic diversity within the population, via conservation translocation, also has to be conducted, Woolloff added.
According to the National Parks Board of Singapore's (NParks) conservation group director, Lim Liang Jim, the Raffles’ Banded Langur population hit a low of 10 individuals in the 1980s.
Lim said NParks implemented a range of enhancement measures to safeguard and improve key habitats of the Raffles’ Banded Langur in Singapore, such as reforestation and enrichment plantings.
For example, Nparks has planted certain food plant species in Thomson Nature Park, as well as trees with spreading canopies that enhance canopy linkages.
It has also installed rope bridges along Old Upper Thomson Road, which help separate the nature park from the Central Catchment Nature Reserve, and further help the langurs move safely.
According to Lim, NParks had worked closely with the Raffles’ Banded Langur Working Group to locate where the langurs habitually cross, and place the rope bridges appropriately.
The Raffles’ Banded Langur Working Group was formed in 2016 to help conserve the species. It involves NParks, academics from local universities, and nature groups from various organisations and agencies in Singapore and Malaysia.
"We will continue to work with the community to come up with strategies to strengthen the survival of our native langurs and other wildlife," said Lim.
One of the most threatened primate species globally
Named after Sir Stamford Raffles, who had first recorded the species in 1822, the Raffles' Banded Langur is characterised by its black fur and white bands on the chest and inner legs. It lives in trees, and feeds primarily on leaves and other plant parts.
Besides Singapore, it can also be found in the southern tip of Peninsular Malaysia, and is one of the rarest and most threatened primate species globally. However, the recovery in the Singapore population is a positive sign.
“With the right protection and management measures in place, we can bring a species back from the brink of extinction," said primatologist Dr Andie Ang, chairperson of the Raffles’ Banded Langur Working Group.
While the progress on protecting the species is "inspiring", Ang said that there is still "much to be accomplished" in preserving the Raffles' Banded Langur and Singapore’s natural heritage, such as the protection of remaining habitats.
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