Puzzling bird behavior in CSRA (car, office, buildings)

[Worren]

Noticing bird droppings on both front doors of my car while parked under the carport I became curious and began looking out more often. Today I saw birds sitting on the mirrors pecking at their reflections in the mirror glass. They also were on my neighbors cars. Looked like they were either fighting with their reflections or maybe thinking it was a way in. As bird droppings are very corrosive I put bags over the mirrors and the birds stopped.
Is this a normal behavior or something new? Never noticed it before.

[GRU_Minion]

Birds have always tried to attack their reflections. Take a look at many office buildings with reflective tint on the windows and you'll often see bird silhouette stickers on them to keep real birds from coming near. When I worked at USC Aiken years ago, it was common in the Humanities & Social Sciences building to have birds crashing into the windows over and over because of the reflective tint on the windows.