Blue birds on my window make me unhappy

[nhman]

Mirrors - depends on the bird species.
Guinea hens LOVE looking in mirrors and they are attracted to them - or anything reflective of their images.
Some Robins will attach a mirror thinking it is a competing bird.
I'd stay away from mirrors.....well, except for a say a concave mirror that would focus the sun lights energy on an object at a focal length in front of it. Could give the bird a "hot" reception! (Can you say L-A-S-E-R like??)