Part 1 of “Birds and glass windows” gives the background to this interesting post. In Part 2 here, we continue the discussion from the rest of the interested birders on their personal encoounters.

Tian Soo has this to say: “Yesterday while reading your messages on birds and windows, a little Spotted Dove (Streptopelia chinensis) smashed right onto my window panel. It’s neck was twisted and died half hour later. Are they that aggressive when driving other birds away or does it simply thought the reflection on the window was clear blue sky? Now I can hear the other birds calling ‘CooCoo’ CooCoo’”

Yap Kim Fatt responded: “Birds don’t commit suicide unless driven by humans to do so. It is not uncommon for birds to fly into glass windows, either maim or kill themselves. It got misled by the transparent glass and tried to fly right through it. A long time ago, a water bird (don’t know name - it had long legs, long slightly curved bill, feathers off-white with brownish spots) flew into my glass window one evening, possibly attracted by the bright light and broke a wing. I nursed it back to health & let it go its merry way.”

Replied Tian Soo: “I think in my case the room is dark so it sees the reflection of the sky and continue its journey. If it sees itself as another bird I don’t think it will crash onto it at this force. Other birds peck at my window everyday. In KF’s case it cannot see the clear glass between the light and itself. I am curious. If they can make these mistakes, there should be lots of dead birds along Shenton Way and Raffles Place with all the tall buildings and glass windows.”

According to YC, birds apparently cannot recognise themselves in a mirror. So when a bird lands in front of a glass window with the background darkened, it sees its reflection. Thinking there is a rival in front of it, it batters against the window pane in an effort to dominate it. Come to think of it, Yellow-vented Bulbuls regularly peck on my bedroom windows.”

Ong Kiem Sian has this to say: “Usually when they fly into glass window it is because they cannot see it as a structure in front. I work in Raffles Place and often see the clouds/sky reflected on the big glass panels of the high-rise buildings. There were several cases of birds dying this way, hitting against building, becoming unconscious and died or somebody could rescue it if the injury was not too bad. I experienced years ago a cuckoo flying through my green chain link fence (not very high may be 5-6 feet high) and the bird got stuck, damaged its wings. Despite feeding and caring it finally died.

“When birds peck on windows or mirrors it is seeing its own image and not recognizing itself. Years ago when I walked home from work, an oriole used to fly to the side mirror of a car. It perched on it and looked at its own image and pecked the mirror. I never had time to go home and take my video. It happened several times and it always returned to the same car.”

The final word comes from bird specialist R. Subaraj: “Pecking at windows is more of a territorial behaviour and many birds do it. As for collision on glass, especially one way mirror windows during the day when the light is coming from the outside, this is a matter of the bird mistaking the reflection of the open space as clear passage. Fast-flying birds are particularly prone and both the escaping prey or attacking predator can meet with a similar fate. Night-flying migrants are particularly vulnerable to all the city lights and glass buildings…..many must crash into buildings at Shenton Way and other places but our army of super-efficient cleaners probably sweep them away before we have a chance to encounter the carcasses. There are many records of stunned, injured or dead birds found at buildings, homes and many were migrants. Some migrants reported or handed in to the bird park include pittas, Black-backed Kingfisher and bitterns.”

…and even the large Rhinoceros Hornbill (B. rhinoceros) is fascinated with its reflection.

We wish to thank Tian Soo, Yap Kim Fatt, Ong Kiem Sian and R Subaraj for their input. Images by YC.

On 27th February 2006, Philip Tatham wrote: “During the last three months, one, and now a pair of, Red-whiskered Bulbuls (Pycnonotus jocosus) visited our apartment block on Jalan Hang Jebat (off Portsdown Road) and spent hour upon hour, almost every day, pecking at our windows. There are six flats in the block and as far as I can tell, the bulbuls peck at all the windows of all the flats. At first we were very worried the birds were trying to get in so we had to switch off the ceiling fans but it seems the birds were only interested in their reflections and ignored the wide-open windows (unlike the mynas, who nest above the windows and perch on the window frames and windowsill all day long). Is this a territorial thing or a breeding matter? And are the Red-whiskered Bulbuls feral, escapees or lost?”

This posting attracted much attention from readers. Jeremy Lee reported seeing Yellow-vented Bulbuls (P. goiavier) attacking the side view mirror of a car. “Some years back a whole flight of starlings crashed into my window pane” he added. “It was a whole series of bangs that I had initially thought was thunder. When I saw the trail of saliva/blood on the window, I checked the flower pots outside the window and there were about eight birds lying on the ground. Only two were still alive and a bit dazed. The rest probably died on impact. Our windows are quite large and it is not difficult for the bird to mistake the reflected image for the real thing.

“The funny thing is that these birds get ‘tunneled’ when they are distracted. Especially for birds with their eyeballs on the side of the head (as in most non-predatory birds). In aviation terms…we call it CFIT…Controlled Flight Into Terrain. This is a situation when a perfectly flyable aircraft gets flown into the ground because the pilots are disorientated or distracted by some other issues in the cockpit.

“In a place like Shenton Way, the birds are probably out in the open and have a big view of what’s ahead. So they are more able to distinguish the glass from the overall picture of the environment ahead. In an environment where greenery is closely meshed with man-made stuff like large windows, things can be quite different.

“Imagine a bird dashing through familiar territory and is suddenly chased by a raptor or some other silly bird cuts into their path and they take evasive action, and then suddenly lock onto a nearby reflection for a safe flight path, they may just make a mistake that will cost them their lives.”

Patricia Thong wrote: “It is perceivable that birds mistake the reflection of the blue sky on windows and fly straight into them. I have observed Collared Kingfishers (Todiramphus chloris) flying into my neighbours’ windows on bright sunny days. Eventually, my neighbours had to place an “X” on their window using tape to prevent that.

“However, I have also observed an inexplicable behaviour by Collared Kingfishers that dived into the trunk of large trees at the MacRitchie Reservoir Park. Surely there is no confusion with reflection, whether of sky or self here. Has anyone else observed this behaviour or would like to suggest an explanation?”

[R Subaraj has this explanation: "As for the diving kingfishers at MacRitchie that crash into trees, I think that they are hunting for lizards or big bugs on the tree trunks and those that crash get it all wrong or more likely, get blinded by the sun before crashing."]

Angie Ng has this to say: “I have witnessed this fascination by the male Scarlet-backed Flowerpecker (Dicaeum cruentatum) with its own reflection on my window panes too. It was just a month before I moved house. The FP kept flying at its reflection and wouldn’t go away. At times it stood at the bottom edge of the glass pane and ‘peered’ into our room; it often stayed for more than an hour each time! When I opened the window to invite it in, it hopped onto the sui mei (Wrightia religiosa) and then away. I did wonder if it knew we were leaving the place.

“My SBFP wasn’t crashing into the glass; it was flying/trying to get through. When it couldn’t, it stood waiting patiently and looking in. It could have been a dozen times trying since it was there when I woke up and still there when I had to leave to run my errands.

“Some years ago, I was entertained by a peacock apparently enjoying itself jumping up and attacking its reflection on a highly polished car. The parked car sustained some serious scratches from its claws; wonder if the driver knew who did it!”

Watch out for Part 2 where others join in the discussion.

Thanks to Philip Tatham for bringing up the subject and to Jeremy Lee, Patricia Thong and Angie Ng for participating in the discussion. Images by YC.