Bird netting or Anti-bird netting, depending on the label, might be a cheap solution @LiamT. The idea is to hang the netting a few inches in front of the window. The birds can't fly through it, but you'll be able to see through it. I've never tried it but I've read many stories, some promotional, about this method being most successful.
https://www.birdwatchersdigest.com/bwdsite/learn/top10/windowstrikes.php