SINGAPORE - Skyscrapers have become an intrinsic part of the skyline in land-scarce Singapore but they are posing a problem for migratory birds.

And buildings in the central and western parts of the island are the ones birds are most likely to crash into, a new study has found.

The study, put together by bird scientists and researchers from institutions such as the Nature Society (Singapore) and National University of Singapore, found that, between 1998 and 2016, 237 migratory birds collided with buildings, and 157 of them or about 66 per cent, died.

Of the 237 collisions, 115 took place in the Central Business District area and a few residential areas on the fringes of the Central Catchment Nature Reserve.

In the west of the island, there were 57 collisions, largely in areas with heavy industrial land use on the edge of the Western Catchment area.

The two areas accounted for 73 per cent of all reported collisions in Singapore.

The study, the first to document bird and building collisions in South-east Asia, also found that certain species of birds are more likely to collide into buildings than others.

The study said: "The birds most vulnerable to collisions with man-made structures are migratory species whose routes pass through major urban centres.

"The problem is exacerbated by light pollution from urban buildings at night, which both attracts and disorientates night-flying birds, leading to increased collision rates in urban areas."

The rise in bird-building collision rates is not unique to Singapore. In North America, estimates of bird deaths from collisions range from 100 million to 1 billion birds a year.

In New York, a growing number of building owners are switching off non-essential lights after becoming aware about the fatal attraction birds have to lights.

Since 2005, more than 90 buildings in the city, including the Rockefeller Centre, Chrysler Building and the Time Warner Centre, have joined the Lights Out programme, which encourages buildings to take a lights-off approach to keep birds safe.

In Singapore, four species - the blue-winged pitta, yellow-rumped flycatcher, western hooded pitta and oriental dwarf kingfisher - together make up 53 per cent of all collisions.

The blue-winged pitta and the western hooded pitta fly into Singapore from the Indochina region, and do so largely at night.

"They may be particularly vulnerable in the vicinity of high-rise, brightly lit housing and office blocks, which are a feature of modern Singapore's skyline and are a deadly attraction to birds," said the study.

The study was done by Mr Low Bing Wen, Mr Yong Ding Li, Mr David Tan, Mr Alan Owyong and Mr Alfred Chia.

It was published in the June (2017) issue of Birding Asia, the bulletin of the Oriental Bird Club - a Britain-based society for ornithologists studying Asian birds.

Mr Alfred Chia, who is from the Nature Society (Singapore) Bird Group, said all it takes is for people to turn off the lights in high-rise buildings, instead of leaving them on throughout the night.

He said: "It may not be practical or feasible for building authorities to make it mandatory for building owners and developers to install bird-friendly glass in building facades."

Bird-friendly glass is a special kind of glass that has UV-reflective patches, which make the glass more visible to passing birds.

As for the current situation, Mr Chia said: "There is one thing that can be immediately done and at no cost - switching off lights in tall office buildings in the city at night. It will contribute positively to minimising the incidences of birds crashing into buildings."

Those who come across dead birds can contact Mr David Tan at 9176-8971. If the birds are still alive, the Animal Concerns Research and Education Society (Acres) should be contacted instead at 9783 7782.