Connie Masters of Balclutha asks :-
Our house has a lot of glass and in early summer typically half a dozen thrushes fly into the windows. There are many other types of birds around but they all seem to avoid the window collisions. Why is it thrushes dont?
Murray Potter, an ecologist at Massey University, responded.
Hundreds of millions of birds perish worldwide each year from crashing into glass windows.
The most frequent victims are the relatively common songbirds that are comfortable around civilisation, but many hundreds of species of bird have been recorded dying this way. Small birds, like fantails and sparrows, are probably just as likely to hit windows as larger birds like song thrushes, but their smaller mass and slower flight speed mean the impacts are less frequently fatal.
Birds hit windows simply because they, like us, often fail to see the glass, or see the reflection of the natural surroundings and fail to perceive the window as a solid barrier. Some birds, particularly during breeding, try to chase off their own reflection, believing it to be an intruder. Others, such as blackbirds and magpies, sometimes show sustained aggression towards their reflection in windows. This occurs most commonly in association with breeding in spring. Young inexperienced birds may also be particularly prone to hitting windows. This may explain why so many thrushes were observed to have hit windows in December - they may have been predominantly young birds.
If you have a window that frequently claims the life of birds, try making the window more visible by keeping curtains closed or by placing stickers on the window.