Yah I hang papertowels on some of ours that they seem to attack.
Last summer we had a goldfinch that would come and play with our cat on a daily basis. He would sit on the ledge of the bay window, chirp until our cat heard him, and then they would play, he would flutter up and down, and she would slam herself against the glass to kill him, they would do this for about 15 minutes, then he would go away, and then come back in a few hours. This went on from the end of May until the end of October. It was hysterical. If the cat was bored, she would wander over and look around for him too. It was really funny.
We keep wondering if he will be back this year.