Second this - if you google anti-collision stickers this should do the trick. Alternatively you could also use some scotch tape (non-transparent) and tape a line across the outside of the window every 3-4 inches for a DIY fix.
How well do they work though? I’ve read that in order to be effective you basically need lines every 50-75 mm, and a few stickers aren’t that effective
That’s true, so closely spaced markings are recommended. I had the same problem and this dotted tape solved it completely. Personally, I didn’t want clip art graphics on my windows, and I like the fact that the dotted tape minimizes interference with my view outside. You can find more information on other strategies here though (like drawing deterrent patterns with bar soap).
*Two inch spacing worked for me, but you might need to make it denser depending on the species you’re accidentally luring