SINGAPORE - Nearly 70 wildlife species, including mammals and birds, have been spotted using a bridge meant to provide wild animals safe passage across Mandai Lake Road since the structure was opened in December 2019.

The developer of the site, Mandai Wildlife Group, gave this update on Thursday (Feb 3), saying camera traps installed along the 140m-long bridge have yielded insights into movements by common palm civets, wild boars, and sambar deer across the structure.

But The Straits Times (ST) has learnt that animals were still being struck by vehicles on  Mandai Lake Road.

In one accident a year ago, a critically endangered Sunda pangolin was killed, its carcass found on Mandai Lake Road.

According to an incident report by Mandai Wildlife Group seen by ST, the pangolin's death was likely caused by a vehicle strike, "based on the carcass condition and location".

"Possible points of access are being investigated and contractors are reminded to conduct daily checks on the hoarding and fencing," the incident report said.

In response to queries, a spokesman for the Mandai Wildlife Group said there were seven roadkill incidents between January 2020 and December 2021 that occurred along Mandai Lake Road and within 500m of the project boundary on Mandai Road. Casualties besides the pangolin include a Malayan colugo, a long-tailed macaque, a wild boar and a red-tailed pipe snake. 

The issue of native animals turning up dead on that stretch of road has been a sore spot for the nature community here since development plans to convert the secondary forests in the area into an eco-tourism hub were announced years ago.

Mandai Wildlife Group is developing the leafy Mandai area, which is located next to the biodiversity-rich Central Catchment Nature Reserve, into a hub of five wildlife parks.

Works for the Rainforest Wild park and the relocated Bird Park - renamed Bird Paradise - have been ongoing since January 2017. The group said last October that Bird Paradise is expected to open this year and the Rainforest Wild park by 2024.

When completed, they will complement the existing three parks there - the Singapore Zoo, Night Safari and River Wonders.

In March 2018, ST reported that native animals that once called the Mandai forests home appear to have been pushed out onto the roads by the development, which involved the clearing of secondary forests.

Several native animals were found as roadkill either inside or within 500m of the project boundary within the first year or so of development.

At that time, Mandai Wildlife Group said that an average of one to two animals are run over on Mandai Lake Road each week - the same as before works started. But their records extend to November 2016, two months before work commenced.

No official data on roadkill incidents on Mandai Lake Road exists, but records from wildlife rescue group Animal Concerns Research and Education Society (Acres) show it was alerted to just one incident involving a monkey on Mandai Lake Road in 2016.

On Thursday (Feb 3), the Mandai Wildlife Group spokesman said that the number of road-related wildlife mortalities between 2018 and 2019 dropped by more than 50 per cent. 

“The practice of closing Mandai Lake Road between 1.30am and 6am daily continues to be in place until the end of the project as a measure to reduce noise disturbance to the nocturnal fauna in the area,” she added. 

For example, permanent fencing along Mandai Lake Road has been implemented to guide and funnel animals onto the wildlife bridge. 

These fencing structures are embedded into the soil and fitted with an anti-climb panel to deter small mammals and reptiles from moving towards the road, said the spokesman for the group. 

“One-way hatch doors are also installed along the length of Mandai Lake Road to give stranded animals access to alternative pathways,” she added. 

Other crossing aids such as rope bridges have also been installed along the road, alongside speed humps and signs urging motorists to slow down.

Asked if these measures would be enough to reduce roadkill incidents when traffic on Mandai Lake Road increases as Covid-19 measures are relaxed, the Mandai Wildlife Group spokesman said the adequacy of road calming measures is reviewed regularly.

Monitoring is in place for potential breaches and gaps along the current fencing infrastructure along Mandai Lake Road, she said. 

“Our focus is to be responsive and adaptive,” the spokesman added. “An example is an increase in road humps from five to eight along the 1.4km Mandai Lake Road, which we put in place to deliberately slow down drivers.” 

Ms Chua Yen Kheng, assistant vice-president of sustainable solutions at Mandai Wildlife Group, said the Mandai Wildlife Bridge creates "vital habitat connectivity and safe passage for wildlife movement".

She added: "The commonly encountered animals in the surrounding forested areas have adapted well to the bridge. These include the sambar deer, wild pigs, long-tailed macaques, as well as different bird species which have been observed nesting on planted trees."

Fast-growing native trees and a combination of species that grow to various heights at maturity have been planted on the wildlife bridge, to achieve a multi-layered forest structure suitable for different animal species, Mandai Wildlife Group said.

"To enrich the ground layer on the bridge, logs, branches and leaf litter from the existing wildlife parks were collected and transported to the bridge," said the developer in a statement.

Log piles act as "stepping stones" or refuge for small mammals, reptiles and amphibians, while saplings salvaged from other sites within the precinct have been transplanted onto the bridge.

Saplings of recently discovered and locally threatened tree species Glochidion obscurum have also been found growing on the bridge. They are the result of animal dispersal, a positive indicator of natural regeneration of flora on the bridge, said Mandai Wildlife Group.

A number of mature Glochidion obscurum trees had been observed within the bridge’s vicinity, serving as a likely seed source for the saplings to establish on the bridge. 

This tree is naturally dispersed by birds and based on the records of fruit-eating birds foraging on and around the bridge, the saplings on the bridge are a likely indication of animal dispersal, said the group.

The group's Ms Chua added: "When the vegetation is mature, we expect that elusive species like the lesser mousedeer and Sunda pangolins will use the bridge to move between the forest patches.

"Our learning from designing and deploying various wildlife-friendly features in a built environment is also potentially useful for projects elsewhere."

Dr Vilma D'Rozario, co-director of the Singapore Wildcat Action Group, said: "I am heartened to hear that over 70 species of wildlife use Mandai’s wildlife bridge. However, I hope that road calming measures could be maintained or even increased to help remove the potential for wildlife road mortality when traffic ramps up to pre-Covid-19 levels."