Hi Captain,
I think some studies may have been done overseas but I don't know of any particular references at the moment. I agree it would be a very interesting study to conduct.
The point I was trying to make is that a nocturnal bird such as an owl may not even see the sticker, so of course it will not be effective.
I think most previous work has looked at impact into windows. Although the stickers may sometimes be effective on windows, this does not necessarily mean they will be useful when applied to a noise barrier, given the differences in scale and the fact that the barrier is in front of a landscape not a building.
Besides, if they need to be as little as 1.5m to be effective, then surely this makes the transparency of the noise barrier pointless - why not change the barrier design to prevent the risk of bird collision in the first place?
