NParks sterilising long-tailed macaques at Maju Forest to manage population

Singapore, a densely populated island nation that champions its "City in Nature" vision, faces a unique set of challenges in managing its biodiversity. The rapid urban development, while creating a modern metropolis, inevitably encroaches upon natural habitats, leading to more frequent encounters between humans and wildlife. Long-tailed macaques (Macaca fascicularis), being highly adaptable and intelligent primates native to Singapore, are often at the forefront of these interactions. Historically, these macaques played a vital ecological role as seed dispersers and forest engineers, contributing to the health of the island’s ecosystems. However, their opportunistic feeding habits and comfort around humans, often exacerbated by illegal feeding, have led to their increasing presence in residential areas, creating friction and necessitating active management interventions.

The sterilisation programme at Maju Forest is not a standalone measure but an integral part of NParks’ broader, multi-pronged approach to wildlife management. How Choon Beng, NParks’ group director for wildlife management, elaborated on this holistic strategy, which includes several key pillars aimed at fostering a more harmonious coexistence. Firstly, significant emphasis is placed on minimising human-sourced food availability. This involves public education campaigns to discourage feeding wildlife, secure waste management practices, and regular monitoring of potential food attractants in residential zones. Secondly, NParks is committed to expanding its outreach and engagement efforts to educate residents on appropriate behaviours when encountering macaques. This includes advice on keeping windows and doors closed, securing food items, and understanding macaque behaviour to avoid provoking them. Thirdly, the deployment of "monkey guarding patrols" in hotspot areas provides an immediate, on-ground presence to deter macaques from entering homes and to guide them back to natural habitats. Lastly, stringent enforcement efforts are being undertaken to deter and penalise illegal wildlife feeding activities, a critical factor known to habituate macaques to human presence and human food, thereby escalating conflicts.

The urgency of these measures is underscored by concerning trends in human-wildlife interactions across the island. Publicly available figures reveal that between 2017 and 2022, the Singapore government received approximately 2,500 cases of monkey-related feedback annually. This represented a substantial 35 per cent increase compared to a decade earlier, indicating a growing challenge that demands proactive and sustainable solutions. This rise in feedback is likely a confluence of factors, including increasing macaque populations in certain areas, greater public awareness leading to more reporting, and the continued expansion of urban infrastructure into areas traditionally inhabited by wildlife.

One of the core tenets of NParks’ strategy is the preference for humane methods, with sterilisation emerging as a scientifically sound and ethically preferable alternative to more drastic measures like culling. Unlike culling, which can disrupt entire social structures and lead to unpredictable behavioural changes in remaining troops, sterilisation allows for the gradual and natural reduction of population growth without causing significant social upheaval. Most macaques undergoing the procedure are sterilised and then returned to their original habitat and social groups. This approach ensures that the existing troop dynamics remain intact, while the number of new births progressively declines over time. For the Maju Forest initiative, NParks has established a dedicated enclosure for trapping macaques for sterilisation. During a recent observation by CNA, the enclosure, located a short walk from the main road, featured at least two cages, though they were empty at the time, indicating the selective and careful nature of the trapping process. Once trapped, the macaques undergo a veterinary procedure, typically a vasectomy for males and a tubal ligation for females, followed by a recovery period before being released back into their environment.

Experts and wildlife advocates largely endorse the sterilisation approach, though they caution that its success hinges on a multitude of factors beyond mere population control. Primatologist Dr. Andie Ang, who chairs the Raffles’ Banded Langur Working Group, emphasised the critical importance of ensuring sufficient habitats for native species. She highlighted that without adequate natural spaces, even a controlled population might struggle to thrive, leading to continued encroachment into human-dominated areas. Dr. Ang also stressed the need for consistent "monkey guarding" efforts in known hotspot areas and robust community engagement. She advocated for organising town halls with residents to not only explain the sterilisation programme but also to thoroughly educate them on the "Do’s and Don’ts" when encountering macaques. Such platforms foster understanding, dispel myths, and empower residents with practical knowledge to minimise conflict, moving beyond reactive measures to proactive coexistence.

The Animal Concerns Research and Education Society (ACRES) also weighed in, with CEO Kalaivanan Balakrishnan expressing a nuanced concern. While supportive of sterilisation as a humane method, ACRES cautioned against potential troop fragmentation. This can occur not only due to sterilisation efforts but also, more significantly, when large-scale development works take place. Balakrishnan pointed out that in Singapore’s highly urbanised context, troop fragmentation is a particular concern because once these macaques are displaced from their familiar territories, they risk being "stranded in the middle of our city." This displacement can lead to increased stress for the animals, higher risks of road accidents, and further instances of conflict as they search for new food sources and shelter in unfamiliar human environments. This highlights the intricate link between wildlife management and urban planning, underscoring the need for integrated strategies that consider the ecological impact of development projects.

Residents living near Maju Forest frequently encounter macaques, often in groups, as often as three times a week. While not all residents have personally experienced direct disturbances, many have adopted precautionary measures. Susan Kwan, a resident, shared her experience: "They go into the patio. If there’s food there, they will take it… so now we just don’t leave any food and things on the patio." Another resident recounted a surprising encounter: "It hasn’t affected me directly… but they were actually at the Cold Storage (supermarket) one time, rambling through the storage area." Mr. Alastair Hunt frequently observes them in the car park or communal garden. Beyond immediate concerns, a prevailing anxiety among residents revolves around the future of these macaques, particularly with impending redevelopment works in the area, including sites like Sunset Way and the former Gillman Barracks. Residents worry about where the displaced macaques will go, fearing that this could exacerbate human-wildlife conflict rather than alleviate it, especially if new developments do not incorporate wildlife-friendly planning or sufficient buffer zones.

Singapore can draw lessons from its own experience in Punggol, another region that has historically been a hotspot for encounters with long-tailed macaques. Residents and businesses in Punggol have reported various issues, including animals rummaging through bins, causing property damage, and entering shops in search of food. NParks initiated macaque sterilisation efforts in Punggol in late 2023, following extensive population surveys and scientific modelling to understand the local dynamics. In 2024 alone, approximately 50 macaques were trapped, with the majority sterilised and returned to their habitat. Kalaivanan Balakrishnan of ACRES lauded this Punggol approach, stating, "It’s one of the best ways to manage this humanely, which is something that ACRES has been advocating for a long time." He emphasised that proactive management of the macaque population in areas like Clementi is crucial to prevent them from facing similar challenges to Punggol in the future, particularly as new residents move in and further development potentially displaces wildlife.

The long-tailed macaque, a species native to Singapore, was estimated to have a population of about 1,900 individuals in the last island-wide census conducted in 2012. These resilient primates can live between 15 and 30 years in the wild, with a female capable of producing between eight and 12 offspring over her lifetime. This relatively high reproductive rate, coupled with their long lifespan, underscores the need for effective population management strategies to prevent unchecked growth that could lead to increased conflict in an urbanising landscape. While NParks has not yet released specific data detailing the impact of sterilisation on Singapore’s macaque population, international precedents offer valuable insights into the potential effectiveness of this approach.

Hong Kong, which has implemented macaque sterilisation programmes for several years, provides a compelling case study. A study conducted there revealed that within three years of implementing sterilisation, the proportion of female macaques giving birth significantly declined from 59 per cent to 31 per cent. Following this initial reduction, both the birth rate and the overall macaque population in the study area remained relatively stable. Researchers in Hong Kong estimated that to prevent further population growth, a sustained effort would be required, involving the sterilisation of approximately 80 to 100 macaques annually. This long-term commitment highlights that sterilisation is not a one-off solution but a continuous management strategy requiring consistent resources and scientific monitoring.

In conclusion, the sterilisation programme at Maju Forest represents a pivotal step in Singapore’s ongoing efforts to manage human-wildlife interactions in an increasingly urbanised environment. By adopting a humane, multi-pronged strategy that combines population control through sterilisation with habitat preservation, community engagement, and responsible human behaviour, NParks aims to foster a sustainable coexistence. The challenges are complex, involving ecological considerations, urban planning, and socio-cultural aspects. However, by learning from past experiences like Punggol and international examples like Hong Kong, Singapore is strategically positioning itself to address these challenges proactively, ensuring the welfare of both its citizens and its precious native wildlife. Continued scientific monitoring, adaptive management strategies, and sustained public education will be essential to the long-term success of this delicate balancing act.