Could CDs (Compact Disc) cause fire if I hang them outside the windows?

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ahkow
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Hi, I live in 6th floor of an apartment. To prevent birds from pooping beside my window, I hang some unlabeled CDs along a string outside the window. The window is facing east, and people start complaining about it, that it might cause fire.

I wonder if that is even possible? I personally do not believe that but I need some advice. Thank you very much.

Sorry if this is the wrong place to post.
 
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I don't think the probability of fire is increased by some randomly oriented CDs dangling on a string, especially in an apartment building which I assume is not even wooden. What exactly is supposed to catch fire there?
 
A CD will NOT act as a 'collecting mirror' because it is flat and not parabolic. That would be the only way that the Sun's rays could be focussed enough to cause burning.
Something that IS a fire hazard is a spherical glass paperweight left in the sun. I have a groove in a table top where the Sun's image was burned into the wood as the Sun moved overhead. Also, a concave shaving or makeup mirror could do the same thing if you were unlucky.
All mirrors should be covered with a cloth when not in use. But not to prevent fires - just to discourage vanity. haha
 
Thank you for your replies, nevertheless I have removed the CD just to prevent further complaints :)
 
Perhaps >500 cd's carefully arranged into a paraboloid could cause a fire :-)