With the construction of Highway 304's wildlife corridors still underway, a survey has found wildlife footprints on top of the traffic tunnels, proving that animals are now adjusting to the presence of the corridor and are able to cross over the road with more safety.

Theerapat Prayurasiddhi, deputy chairman of the national reform committee on natural resources and environment, said he carried out the survey with the Department of National Parks, Wildlife and Plant Conservation.

It serves as fresh evidence that some wild animals have already changed their behaviour and are crossing over the road to reach the other side of the forest.

"I have seen footprints of deer and chamois on the top of the tunnel. Last September, a man took a video clip of a chamois close to the tunnel construction site. It might be the same case, as I have found the footprints.

"Its habitat is likely to be between Khao Yai National Park and Thap Lan National Park, which is now linked by the corridor over the tunnel," he said.

He said the department will set up a camera trap and sand trap to follow up on the behaviour of wild animals in the corridors, which are being built to limit the number of wildlife deaths caused by road accidents. In 2016, it was estimated that passing cars on the route reached 29,000 cars per day, of which 7,500 were heavy trucks.

Upon the inscription of the Dong Phayayen-Khao Yai Forest Complex as a World Heritage Site in 2005, the World Heritage Committee asked Thailand to carry out a study on setting up wildlife corridors to link the western and eastern sectors of the forest complex, which are Khao Yai National Park and Thap Lan National Park.

The wildlife corridors are built as passages for wildlife with traffic using tunnels or overpass bridges to maintain the animals' environment. Mr Theerapat said the two tunnels at the 2.41 kilometre and 26-29th kilometre marks where the footprints were found are already in use.

Meanwhile, no traces of animals have yet been found under the elevated highway bridge at the 42nd kilometre mark. The bridge is likely to be complete in April.

He said the footprints on top of the tunnels are evidence which proves the success of the wildlife corridor and shows it is worth the investment. The cost may be steep, but the corridor has shown it can spare the lives of wildlife, he said.

According to the Department of Highways, animals that are expected to use the wildlife corridor include wild boar, muntjac, Asian black bears, the Indochinese water dragon, frogs, and puddle frogs. The study is consistent with the department's report, which found that the forest along Highway 304 is a significant habitat for boar, deer, tigers, gaur and elephant.