Design of noise barriers to change in bid to save birds
SCMP 16-10-2009
Officials plan to modify glass panes on a Yuen Long road
Highways officials plan to modify the glass pane design of noise barriers on a Yuen Long road after at least 50 birds hit the barriers and died over the past three years.
The officials are working with conservation officers to devise a better design to frighten birds away from the barriers. Design and installation could be completed in a few months.
One option is to replace the black hawk silhouette stuck onto the glass panes since late last year with stickers of opaque stripes or colourful circles to minimise the transparent-glass surface.
The birds, mostly smaller species and some rarely sighted, have been found lying dead or semi-conscious at the bottom of the barrier, which was built along Shap Pat Heung Road in 2006 to cope with increasing traffic brought by property development in the area.
They had apparently collided with the three- to six-metre-tall transparent glass barriers, which stretch intermittently along the road for a few hundred metres to shield villages from traffic noise. In some sections, there are trees immediately behind the barriers.
Fifty-three birds from 25 species have fallen prey to the barriers so far, leaving 50 dead and three injured. The last collision happened about a week ago.
Alan Lam Ngo-lun, a dedicated birdwatcher who passes the noise barrier almost every day and has compiled a detailed list of the victims, said he suspected that the transparent glass barriers, which looked invisible to birds, were to blame.
"The actual death toll could be far higher than I have recorded, as some dead birds could have been removed by street cleaners before they were found," Lam said.
Smaller birds, as little as 11cm in length, were found to be particularly prone to hitting the barrier, as they usually flew closer to the ground. But bigger birds, as long as 40cm, were also found dead.
The most vulnerable species were resident birds that lived nearby, such as the Japanese white-eye, a common and tiny songbird species that accounted for one-fifth of the toll. About 10 per cent of the victims were Eurasian tree sparrows.
Rarely sighted migratory bird species including the Siberian blue robin were also on the death list.
Lam said it was difficult to explain why some birds hit the glass and what circumstances were more conducive to collision, because systematic research into the problem was lacking.
He said such collisions had also become more common in urban areas, with more and more buildings being covered with reflective glass panes that might distort birds' view of the world.
According to the National Audubon Society in the United States, there are about one billion bird deaths resulting from collisions with windows and buildings each year in the United States.
Jackie Yip Yin, a nature conservation officer from the Agriculture, Fisheries and Conservation Department, said it had asked the Highways Department to consider remedial measures, after reading Lam's report.
She said most birds could have hit the glass early in the morning or when visibility was reduced.
Highways Department chief engineer Tse Chun-tat said it was still studying the best options to minimise bird collisions, but replacing the transparent barriers with non-transparent ones might not be financially viable or welcomed by residents.
"We also have to consider the visual impact on the residents, as a non-transparent barrier might block their view, " he said. "This is a balance we have to strike."
He said it might take some time to design the new stickers, and the department would monitor their effectiveness before considering whether to extend the new techniques to other noise barriers.
DOCUMENT ID: 200910170270355
