The Hong Kong Bird Watching Society on Monday said the use of reflective materials in new infrastructure in the city is causing more birds to collide with buildings.

The group said it recorded about 200 bird collisions from September to December last year, and more than 90 percent of them were fatal.

Some surfaces, such as those made of glass, can reflect natural landscapes like trees, creating an illusion for birds, the society said.

Its conservation officer, Wong Suet-mei, said the external walls of new buildings generally consist of more glass than older buildings.

"In the business area in Kowloon Bay or North Point, there are lots of new commercial buildings with large, extensive mirror glass or reflective surfaces," she said. "This is a big trap for birds because they will be faked by the unreal images they see through the glass."

Wong said one black spot for bird collisions, Mei Foo MTR Station, has put anti-bird collision stickers on 107 glass panels after about 30 cases happened there.

She added that a reduction in the use of glass and reflective materials on external walls of future buildings would help, but the government could also tackle the problem through legislation, as other places have done.

"New York has introduced a law which requires all buildings that are made of glass or mirror materials to adopt anti-bird collision materials. It is a mandatory measure. Although Hong Kong is lagging behind, we can still start now," Wong said.