Managing Growing Wild Boar Population in Bukit Panjang

Mr Liang Eng Hwa asked the Minister for National Development (a) what are the causes for the recent wild boar attacks in Bukit Panjang; and (b) what further measures are needed to prevent wild boar attacks and ensure the safety of residents living near nature reserves.

Mr Liang Eng Hwa asked the Minister for National Development (a) what are the actions taken by NParks when the public reports wild boar sightings at the residential neighbourhoods; (b) whether the current number of wild boars at the nature reserves are at an ecologically sustainable level; and (c) what further measures and plans are there to manage the population of wild boars.

Members have asked about what the National Parks Board (NParks) is doing to manage Singapore's wild boar population and to ensure public safety. Public safety is our priority. We want residents to feel safe in and around our green spaces. That is why we take a proactive, holistic and science-based approach in managing the wild boar population.

Wild boars are naturally found in many parts of the world, including Singapore and our region. For the most part, wild boars travel in herds and stay within forested areas.

While Bukit Panjang and the adjacent Zhenghua Nature Park do not have a resident wild boar population, wild boars appear from time to time due to the estate's close proximity to nature reserves and other forested areas such as Chestnut Nature Park and Dairy Farm Nature Park.

We know that residents in Zhenghua and Bukit Panjang are concerned about the recent wild boar incidents in the area. NParks has taken steps to mitigate the risks and will be closely monitoring the situation.

For instance, NParks has trapped and removed 19 wild boars from the vicinity of Bukit Panjang since May this year. In addition, NParks has been installing exclusion fences to reduce the possibility of wild boars entering the estate. NParks is also working closely with the grassroots and the Holland-Bukit Panjang Town Council to engage the community on proper food waste management, to reduce human-generated food sources that may attract wild boars.

Wild boars have high reproductive rates, giving birth up to twice a year with a litter size of up to 12 piglets. Female wild boars can start reproducing from 18 months of age. Wild boars also do not have natural predators in Singapore. NParks, therefore, has to actively manage the wild boar population. This includes carrying out habitat modification, such as removing oil palms to reduce wild boars' food sources. In line with the practice in many other countries, NParks also removes boars where necessary to ensure public safety. Based on studies by NParks, these measures have helped to keep the wild boar population in our nature reserves stable, at a density that is lower than those recorded in similar forest reserves in the region.

NParks is also working closely with stakeholders on public education and outreach, to promote safe and responsible human-wildlife encounters. This includes discouraging the feeding of wildlife, which can alter their natural foraging behaviour and cause them to rely on humans for food. NParks does this through public education as well as enforcement action against illegal feeding of wildlife. NParks is also engaging the community on how to respond to wildlife sightings, such as remaining calm and keeping a safe distance if they encounter a wild boar.

When a member of the public reports a wild boar sighting, NParks will respond immediately. NParks will trap and remove any wild boar that is found in a residential area, to ensure public safety. NParks will continue to take a comprehensive science- and community-based approach to manage Singapore's wild boar population and to ensure public safety.

Thank you, Sir. First and foremost, I would like to thank the Senior Minister of State and also his NParks team for coming down to the Nature Park at Bukit Panjang, to assess the situation and to announce enhanced measures to deter the wild boars from coming to our area.

Two supplementary questions. Firstly, as what the Senior Minister of State has said in his reply that NParks will be putting up exclusion fences to deter the wild boars from coming in. So, can I ask the Senior Minister of State how effective has that been. And in the case of Bukit Panjang, we have a very lengthy border with the nature reserve and nature parks, so, whether that is actually possible to exclude wild boars from coming in.

The second question is, as he also mentioned about the high reproductive rate of the wild boars and that there being no natural predators, so how is NParks going to ensure that the population growth of the wild boars will not cause damage to the ecosystems within the nature parks and whether the nature parks indeed have the space to accommodate so many wild boars.

Sir, on the first question by Mr Liang Eng Hwa. On the effectiveness of the exclusion measures, let me set the context by saying that in certain hotspots, NParks has installed exclusion fences that adhere to specific guidelines, such as the depth of installation and the type of materials used.

These have been effective in restricting wild boars' access to the fenced areas. In some areas, NParks has also deployed cattle grids, which are metal grates designed with gaps that are wide enough for the feet of hooved animals, such as wild boars, to enter. This deters such animals from crossing the grid, whilst still allowing people to cross. In Pulau Ubin, it has been observed that wild boars tend to avoid stepping across such cattle grids.

And therefore, to restrict the wild boars access to Zhenghua Nature Park, NParks has been installing a combination of exclusion fencing and cattle grids, at three access points where we have deemed it more likely that wild boars could enter the residential areas.

The cattle grids at the Bangkit underpass were completed on 23 June 2023 and our monitoring shows that this grid, as well as the areas with exclusion fencing, have been effective so far. NParks is also installing a combination of exclusion fences and cattle grids along Chestnut Avenue and under the Gali Batu flyover. These works are expected to be completed by end-August 2023. NParks will continue to monitor the efficacy of these measures, moving forward.

On Mr Liang's second question, I would like to share with the Member that NParks carries out tracking studies to monitor changes in the wild boar population and to identify hotspots. Based on NParks' findings, the wild boar population in Singapore's nature reserves has remained relatively stable.

Between 2019 and 2020, NParks conducted a study using camera traps which found that the density of wild boars was about 6.57 per kilometre square in our nature reserves and about 5.22 per kilometre square in our nature parks. These densities are lower than those recorded in larger tracts of forest reserves in the region with similar vegetation types.

As I shared in my earlier reply, NParks will continue to take a comprehensive science- and community-based approach to manage Singapore's wild boar population. This includes conducting habitat modification to reduce their food sources, managing their movements through fencing and hoarding, and removing wild boars where necessary to ensure public safety. We will also continue to discourage the feeding of wildlife and take enforcement action against such acts.

Thank you, Deputy Speaker. I would like to ask the Senior Minister of State – was the presence of a dog in the latest incident at Zhenghua Nature Park, a contributing factor to the incident? And the second supplementary question is, if the wild boar population is left unmanaged, what is the impact to our biodiversity?

Sir, I thank Mr Edward Chia for his two questions. The first one is on walking dogs. For dog owners who walk their dogs in parks that are near forested areas, we encourage them to avoid walking their dogs at night due to the low visibility and the possibility of encountering nocturnal wildlife. If a dog owner sees a wild boar in the distance while walking his or her dog, the owner is advised to keep the dog close by tightening its leash and to move away from the wild boar as quietly and rapidly as possible.

And on his second question on the ecological role of wild boars, as I mentioned earlier, wild boars are indigenous to many parts of the world including in Europe, parts of Asia in Singapore and the region. They do serve  important ecological functions such as acting as seed dispersers and helping with soil nutrient recycling with their rooting behaviour. Wild boars are omnivorous; they eat not just vegetation but they also dig soil to eat the small worms and insects under the soil. Their feeding behaviour helps to have a positive impact on the ecosystem by dispersing seeds. So, in this way, they can help to regenerate native flora. Boars also compete aggressively with other species for food. So, they play an important ecological function.

But at the same time, I think we look at two extreme suggestions that have been raised by different people. One is firstly, as I explained in my earlier reply, that we proactively adopt a science-based, community-based approach to manage the wild boar population, importantly to ensure public safety. But on the other hand, it is also impossible to not have any wild boars in Singapore at all, not least because within our region, there are many wild boars outside Singapore and they can swim to Singapore as well.

So, our approach is a proactive one, using a science- and community-based approach to manage wild boars and to maintain the balance in our ecosystem.

Thank you, Sir, and I thank the Senior Minister of State for sharing about the population density. But could I also ask, what is the carrying capacity of our forests for wild boars in Singapore and also whether NParks has the projected carrying capacity as we develop more forested areas?

Secondly, I appreciate that the Senior Minister of State has stressed again that our approach is science-based and I hope we continue this science-based approach. But could you clarify how it would be science-based if we are really basing it on complaints? When there are complaints, we go in and remove a few wild boars. And again, considering the high reproduction rate of these wild boars, how effective is it to just remove a small number of wild boars and kill them?

Sir, I thank Mr Ng for his two questions. I explained earlier about our study which used camera traps in our nature parks and nature reserves. And we benchmarked them with some of the comparable densities that we found in the region of similar tracts of land and similar vegetation. But it is not a complete science. It is something for which we have to find balance. When I say "science-based", it is that we want to look at evidence and we work very closely with our Institutes of Higher Learning (IHLs), researchers, international partners and industry partners, to make sure that our approach is in line with best practices around the world.

On his second point about how effective it has been, I also mentioned earlier in my reply how we measure their density and look at comparisons around the world. But it is also not just about removing wild boars. I explained our approach earlier, in terms of how we have exclusion fences, cattle grids, and how we work together with the community to educate members of the public and our residents about feeding wildlife. And how we use a science-based approach to track the carrying capacity or density of wild boars.

So, it is a holistic approach. I am not saying that we are perfect or that we have found the answers. This is an issue that does not just confront Singapore. Many other jurisdictions, many other countries that we speak to beyond Asia, in Europe as well, face the same problems and challenges. We are constantly working with them, understanding what they do and updating our playbook here.