Birds and glass windows - 2
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.