“A randomised, replicated and controlled experiment found that placing bird feeders close to windows reduced the number of collisions with the windows, and the number of fatal collisions.”

 - Conservation Evidence

Klem D. Jr., Keck D.C., Marty K.L., Miller Ball A.J., Niciu E.E. & Platt C.T. (2004) Effects of window angling, feeder placement, and scavengers on avian mortality at plate glass. Wilson Bulletin, 116, 69-73

This feeder is right by the kitchen sink: not only have we never had bird get injured at this window, we also get to watch them up close and personal.

The object placed on the glass allows them to recognise the barrier, and they also slow their flight when approaching the perch: if they do get injured, odds are it won’t be severe or deadly.