Rooftop hanging a long string tied with CD’s - very annoying!

Does anyone know what I can do if the person living on the rooftop of the next tower hangs a string tied with CD’s with the purpose of shooing the birds away? The string hangs from level 6 down to level 4 and unfortunately my floor is visible to it. CD’s are reflective, approx 5-6 cd’s apartfor each floor so total approx 15cd’s, very annoying since any light (sun/moon) reflects and my dining room window can see it directly and clearly!

The purpose is so his/her car parked directly below doesn’t get bird shit. Extremely selfish!!

Management has been informed but they seem to be useless.

Is this legal? What Dept/ Who can I contact to have it removed?