The girls were at it again today. They caught a spotted towhee and brought it in to play with. I heard the excitement and took it away from them. I've always had a way with birds, they calm right down when I hold them. There hadn't been towhees at the feeder during the winter, and there have been quite a few of them in the last couple of weeks. I think they must be migrating through.
Maybe that's why the cats are being more successful in their hunting -- Kate has been complaining about the same phenomenon -- the passers-through don't know about the evil felines and aren't as cautious as the local birds.
I locked the girls in the house the rest of the day as a reward. I hope their little cat brains figure out this cause and effect.