Nature in our Man-Made World

This challenge has attracted some REALLY excellent entries of close-up or macro examples where nature has used a man-made object or structure to its advantage. This is what I had expected in this challenge, and thought I had made that fairly clear in my theme.
However, there have been numerous entries where the subjects are too large, or too distant, or too fleeting to be considered a permanent use of the man-made object. (How long does a bird stay on a wire before flying away?)
In the interests of not pulling out too much more of my hair, I'm letting many of these questionable entries stay in the challenge, and the voters will be able to decide what they feel is the correct interpretation of the theme. (Just because I think it should be interpreted one way does NOT mean that I'm right and others are wrong!)
Cheers,
Ruth :-)