Collision into buildings cause of many birds’ deaths: Study

Mr David Tan (at right) with the carcass of a Changeable Hawk-eagle (Nisaetus cirrhatus) and Dr Yong Ding Li with the carcass of an Oriental Pied Hornbill (Anthracoceros albirostris). Of the 362 carcasses picked up between November 2013 and last October, 104 were found at the base of buildings and exhibited injuries confirming their deaths were the result of building collisions, said Mr Tan. Photo: Mark Cheong

By Audrey Tan, 29th January 2018;

Birds here are dying from encounters with an unexpected “predator”.

A new study by scientists here has shown that almost a third of resident birds found dead in Singapore over a four-year period were killed because of collisions with buildings.

Between November 2013 and last October, a total of 362 bird carcasses were picked up by ornithologists from institutions such as the National University of Singapore (NUS), non-profit body BirdLife International and Nature Society (Singapore). They were alerted to the carcasses by members of the public.

The study’s lead author from NUS, Mr David Tan, said 104 of the carcasses were found at the base of buildings and exhibited forms of facial injury or head trauma, confirming that their deaths were the result of building collisions.

It was not possible to pinpoint the causes of deaths for most of the carcasses – 225 of them – although the remainder were killed by, among other things, vehicular collision and attacks by animals such as cats.

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 one billion a year.

The Singapore study, published last November in The International Journal of Tropical Veterinary and Biomedical Research, also found some species of resident birds were more susceptible to building collisions. Pink-necked Green Pigeons (Treron vernans), Asian Glossy Starlings (Aplonis panayensis) and Asian Emerald Doves (Chalcophaps indica) seemed exceptionally vulnerable, making up 64 out of the 104 carcasses found.

The fact that all three species are forest-edge fruit-eaters suggests that both feeding patterns and habitat affect a species’ susceptibility to collision, the study said. “Given the patchy distribution of parks and forest fragments in Singapore, it is likely these nomadic forest-edge frugivores pass through urban areas as part of their foraging movements, which increases the likelihood of building collisions occurring,” the scientists wrote in the paper.

Dr Yong Ding Li from Nature Society (Singapore) said this suggests that buildings near nature areas could incorporate wildlife-friendly measures in their designs, such as reducing the use of huge glass panes which birds tend to crash into.

The findings of the recent study mirror the results of an earlier one focusing on causes of death for migratory birds in Singapore, done by the same group of researchers. That study, published last June, found that between 1998 and 2016, 237 migratory birds collided with buildings and 157 of them died.

On the need to differentiate between migratory birds and resident birds, Mr Tan said: “Migratory birds are pass-through species, not long-term residents, so the factors that result in collisions may be different.

“For example, why is Jurong West a death hot spot for migratory birds, but not for resident birds?”

But the latest study found two regions where resident and migratory collision hot spots overlap: in the Clementi area, near the NUS campus, and in the Central Business District. Finding out the reasons for this – such as whether it was due to light pollution-is what the scientists hope to do next.

In New York, a growing number of building owners are switching off non-essential lights after becoming aware of the fatal attraction birds have to lights. Since 2005, over 90 buildings in the city, including the Rockefeller Centre, have joined the Lights Out scheme, which encourages buildings to take a lights-off approach to keep birds safe.

Here in Singapore, scientists are hopeful that more can be done to reduce bird-building collisions. Mr Tan is in touch with owners of buildings where dead birds have been found, such as at Outward Bound Singapore (OBS) on Pulau Ubin.

An OBS spokesman said a staff member has found three bird carcasses over the past two years. “As part of our efforts to better understand and appreciate the biodiversity of our flora and fauna on Pulau Ubin, we welcome the opportunity to work with Mr David Tan on his research efforts.”

Source: The Straits Times

Spotted Dove (Spilopelia chinensis)
Sungei Buloh Wetland Reserve, 2nd February 2015

A beautiful but unfortunately deceased Jambu Fruit Dove (Ptilinopus jambu), a near threatened (IUCN conservation status) mangrove/rain forest species, but inexplicably found dead at the void deck of HDB estate. (Investigators suspect suicide but are not ruling out fowl play). Spotted by Veron Pwa at her void deck

Source: Sean Yap Instagram

An undergrad reported this dead male Jambu Fruit Dove , listed as near-threatened by the IUCN, today. The bird was found at the base of an apartment block with no apparent external injuries and no signs of head trauma, except that the neck felt unusually loose. Will have to dissect the bird to determine cause of death.

Source: David Tan, on Dead Birds Facebook Group

Not all the dead birds we find at this time of the year are migrants. Some, like this Emerald Dove (Chalcophaps indica), are year-round residents that meet with their untimely end while dispersing locally to forage for food. Unfortunately for this Emerald Dove individual, it died immediately after crashing into the glass sliding doors of a condo unit along Tampines Ave 1.

Source: David Tan Instagram

Picked up an Emerald Dove yesterday after it crashed into the glass sliding doors of a second floor unit in a brand new condo development. Not a migratory species, but a ground-dwelling forest frugivore that likely disperses between forest patches as part of its foraging strategy. This individual was probably in transit between forest patches because it was found nowhere near a forest.

Source: David Tan, on Dead Birds Facebook Group

This morning I picked up the body of a juvenile Jambu Fruit Dove (Ptilinopus jambu) from the United World College Southeast Asia Dover campus. As far as pigeons go this is one of the most beautiful in Singapore, and one of the more elusive migrants to find. Although the primary cause of death is likely to be the highly reflective glass on the second floor of the biology building, additional secondary injuries on the neck and breast suggest that it may have been attacked by a predator such as a goshawk (Accipiter sp.) as well.

Source: David Tan Instagram

By far one of the most beautiful forest birds in Singapore, the Emerald Dove (Chalcophaps indica) is commonly found walking on the forest floor foraging for fallen seeds and fruits, although sometimes we receive tragic reports of individuals that die after accidentally crashing into buildings.

Source: David Tan Instagram

The NUS Kent Ridge campus serves as a hotspot for migrating birds, but not all of them make it through alive.

This female Jambu Fruit Dove (Ptilinopus jambu), for instance, died today after flying into a glass door at the NUS Computer Centre. It’s since been taken back to the Avian Evolution lab for DNA sampling and preservation.

Source: David Tan Instagram

Received a gorgeous male Emerald Dove (Chalcophaps indica) carcass today after it flew into a window somewhere in Yishun and broke its neck.

The males are identifiable by the white and grey feathers on their head and shoulder areas, whereas females are a lot browner.

David Tan Instagram