They've been attacking the feeder on and off all day. If they manage to get in, we'll have the whole swarm of them in the garden.
On a happier note, I saw a blue tit eating from the FlutterButter feeder (hanging down from the main feeder in the photo). At last! It's been up for a few months, and the only taker has been the squirrels... and they are really struggling to get in to it. (ha!)