The new-to-me old rusty wrought iron bakers rack outside my window has become a launching pad for birds. I heard thumping noises and looked out to see 2 pigeons and a robin taking turns throwing themselves at the top of the window. I chased them away once, futily. Something up there is so intriguing to the birds they risk a major headache to reach it. Nothing of note hung near the window but I noticed some buggy-looking stuff under the window frame.
Aha, bugs are noteworthy to birds. So I grabbed my insect spray and did my best to rid the area of temptation for birds to bash in thier heads. Is that why we use the term "birdbrain?"