Window decals may help. They come in all different shapes and sizes. Here are a few examples:
[ame=http://www.amazon.com/Window-Alert-WA-BUTTERFLY-Butterfly-Decals/dp/B001OE6WHG/ref=sr_1_2?ie=UTF8&qid=1436535545&sr=8-2&keywords=window+decal+for+birds]Amazon.com : Window Alert Butterfly Decals : Bird Window Decals : Patio, Lawn & Garden[/ame]
[ame=http://www.amazon.com/Window-Alert-WA-HUMMINGBIRD-Hummingbird-Decals/dp/B001OE5HIG/ref=sr_1_3?ie=UTF8&qid=1436535577&sr=8-3&keywords=window+decal+for+birds]Amazon.com : Window Alert Hummingbird Decals : Bird Decals For Windows : Patio, Lawn & Garden[/ame]
[ame=http://www.amazon.com/Birds-View-window-Clear-Etched/dp/B00K65NNIK/ref=sr_1_6?ie=UTF8&qid=1436535577&sr=8-6&keywords=window+decal+for+birds]Amazon.com : Bird's Eye View window film (6) 4X4 Inch, Clear/Etched : Patio, Lawn & Garden[/ame]