The Dusky langurs of Penang: Navigating urban life with finesse

In the bustling cityscape of Penang, Malaysia, amidst the cacophony of human activity, exists a quieter, more elusive population – the Dusky langurs. These captivating primates, also known as leaf monkeys, gracefully navigate the urban landscape, carving out their existence amidst the urban jungle. With their distinctive charcoal fur and soulful eyes, they are an integral part of Penang’s ecosystem. 

The Dusky langur is classified as endangered on the IUCN Red list.

But, their future is not at all secure. Although they are quite able to adapt to urbanisation, Dusky langurs face significant conservation challenges. Habitat loss and fragmentation due to urban development threaten their long-term survival. Encounters with humans also pose risks, as langurs may be subjected to harassment, capture, or even injury from traffic accidents. To find out more about this issue, we are eager to learn from the very experts: the Langur Project Penang. “Let’s meet at dawn at the church,” says the message we receive from Hui Yi, environmental communicator of the project. 

The early Dusky langur catches the mango

As the first light of dawn breaks over Penang, we meet Hui Yi next to a football field, in the middle of a residential area. We are on a mission to observe the elusive Dusky langurs in their urban habitat, but that it will be in the middle of a residential area…that we didn’t expect at all. Armed with binoculars, cameras, and a notebook, we start walking around the neighbourhood, hoping to catch a glimpse of these adorable looking primates. 

With practised eyes, Hui Yi scans the treetops, searching for signs of movement amidst the foliage. “The Dusky langurs are usually active from dawn until around noon, depending on the heat, and then from late afternoon to dusk,” she tells us. The team of Langur Project Penang (LPP) – working with local citizen scientists – follows a specific group in the city twice a week, and conducts behavioural observations, collecting data on their movements and food sources. 

With the first rays of sunlight, the Dusky langurs become active in the city. With Hui Yi from the Langur Project Penang, we follow the fallen mangoes and locate them in a nearby mango tree.

We are walking between rows of houses and busy roads, and I still can’t believe that this endangered primate can live in such urban environments. But to my surprise, as the sun climbs a tiny bit higher, the langurs begin to stir. We spot some movement from a nearby mango tree. Suddenly, a flash of dark fur catches our eyes – a Dusky langur perched on a branch is staring back at us. Silently, we observe, careful not to disturb her in her natural morning routine. Soon enough, more langurs emerge from the shadows, moving effortlessly among the branches. Some nibble on leaves while others pluck unripe mangoes, which land half-eaten in front of our feet. They are so playful and acrobatic, leaping from branch to branch, that it’s impossible for our eyes to keep up with their movement. But how can they survive on these single trees, surrounded by roofs and roads?

Soon enough, we find the answer. They move from tree to tree on electricity lines, they use the tops of cars parked on the street, and move around on the roofs. “Dusky langur families in Penang often move between forest and city. Ultimately, habitat destruction forced them here, and fruit trees attract them,” Hui Yi tells us. 

The Dusky langurs of Penang use electricity wires, roofs and fences to get around in residential areas.

The Dusky langur – community relationship

Dusky langurs are leaf-eaters (folivores), they generally feed on young leaves, shoots and seedlings, but can also digest unripe fruit. This is why the trees in people’s gardens are particularly attractive to them, as we learn from Mr. Tan, a local resident, who joins us on our morning observation. He explains that Dusky langurs are a nuisance for residents, especially the elderly. 

Some people who try to sell their fruits are frustrated about their presence. In the past, especially after the langurs appeared in the urban areas, there were many conflict situations. When moving between locations, they may cause damage to roofs and electricity wires. It even happened that a few of them got into houses through an open window, and made a big mess. There was apprehension and concern among residents, who also contacted the wildlife department, and demanded their translocation. This is when LPP became active. 

Mr. Tan, local resident and citizen scientist with the Langur Project Penang shows us the platfrom he built in his own garden, which can serve as a safe space for the resident Dusky langurs.

Through their work with the community and getting used to their new neighbours, residents started accepting the langurs. Mr. Tan remembers when he was still one of the people who chased away the newcomers as soon as he saw them in his garden. But over time, as he spent more time observing them, he started appreciating them. Apart from participating in monitoring the langurs, Mr. Tan made his garden langur-friendly, by installing a wooden platform, where they can stay and rest above ground. “If I chase them away from my trees, where should they go? These monkeys have so little space left, I am happy to provide a safe refuge for them in my garden when they need it, where nobody bothers them.”

At a crossroads when crossing roads

Aside from their relationship to residents, Hui Yi tells us that road accidents can have profound effects on Dusky langur populations, both directly and indirectly. The loss of individuals due to collisions can disrupt social structures and reproductive dynamics within langur troops, leading to decreased breeding success and population decline over time. Langurs know that being on the ground is not safe for them, which is why they prefer a canopy cover, however, electricity lines are not secure either. 

Langur acrobatics on electricity wires. Using wires to cross requires a good balance and is not without risk for the Dusky langurs.

With their agile movements and natural curiosity, langurs may naturally look at the electricity wire network in the city as a corridor to move around. However, contact with cable wires can result in fatal electrocution for not just the langurs, but also macaques, giant squirrels and all other wildlife that uses them, especially in areas where power lines intersect with trees or other structures. At the same time, langurs can lose their grip on the wires, and fall to the ground below, leading to severe injuries or even death. 

Preserving Penang’s prized primates

In response to the declining population of dusky langurs and the increasing conflict in urban areas, Dr. Jo Leen Yap, a wildlife researcher and environmental educator, initiated the Langur Project Penang in 2016, with the support of the Malaysian Primatological Society. Her aim is to study, protect, and raise awareness about the challenging case of these endangered primates, ultimately fostering coexistence between humans and urban wildlife.

Within the project named ‘Bridge To Coexist’ started in 2023, one of the primary objectives of LPP is to better understand the behaviour, ecology, and habitat requirements of dusky langurs in an urban environment. Through field surveys and camera trapping, researchers gather data to inform conservation strategies and management plans.

Furthermore, LPP actively engages local communities, government agencies, and stakeholders to foster conservation awareness and promote coexistence with dusky langurs. They hold educational programs, community workshops, and various outreach initiatives to instil a sense of stewardship and appreciation for Penang’s unique biodiversity, while also offering sustainable methods to mitigate problematic human-primate interactions. These include not feeding wildlife, closing windows and doors, securing waste disposals not to attract scavengers such as macaques, driving cautiously and supporting conservation efforts.

Hui Yi shows us some of the education material by the Langur Project Penang, that aims to show people how can there be better coexistence between humans and primates.

In 2019, LPP made history by installing Malaysia’s first artificial urban canopy bridge – an elevated pathway spanning across roads or fragmented landscapes – in Penang. This trial proved successful, unlocking a realm of opportunities for the preservation of arboreal wildlife in Malaysia. “We identified potential accident hotspots, and by erecting canopy bridges that are built so that they are much safer for primates to use, our aim is to diminish incidents of roadkill,” explains Hui Yi. After the success of the first bridge ‘Ah Lai’s Crossing’ in 2019, in February 2024 a second canopy bridge, ‘Numi’s Crossing’, was installed with the help of APE Malaysia

The location of Numi’s crossing, over a busy highway. This canopy bridge provides a safe crossing not only to Dusky langurs, but many other wild residents of the city as well.

The first camera trap photos of Numi’s crossing show its success among Dusky langurs, and the launching event attracted a big crowd as well. Photos by: Langur Project Penang

“The bridge, Numi’s Crossing, symbolising hope and peace, aims to assist dusky langurs and treetop animals in the area to cross roads safely and to act as an identity of empathy, compassion, and, most importantly, coexistence among humans and urban wildlife in Penang.”

The announcement of Numi’s crossing by the Langur Project Penang

“Some residents demanded the translocation of dusky langurs, but there would be many obstacles, and with the decreasing natural habitats that humans have taken away from them, it’s impossible to guarantee that they wouldn’t move back to the urban jungle,” adds Hui Yi. After the massive loss and fragmentation of habitats, primarily driven by urbanisation, these dusky langurs have adapted to their new reality. They found a way – a very challenging one, full of unknown threats – to survive. Their adaptability in a way showcases the resilience of nature to environmental changes. 

The Dusky langurs have done their part, and now humans must do theirs. Caring for our urban wildlife means safeguarding the delicate balance between nature and city life. Beyond their clear conservation value as endangered primates, their presence in Penang can be a reminder that humans are fundamentally interconnected with the natural world, and that everything we do to our environment will trigger a response. The health of ecosystems and the survival of species like the Dusky langur are intertwined with human well-being, therefore protecting them and their habitats ultimately preserves the beauty and wonder of nature for future generations.