The Bully, Bullied

Bully Cat, aka Chico, has been the neighborhood bully for years. He's well-known around the neighborhood, and depending on whether he's killed/maimed your cat, he's either well-loved or well-hated.
He's been an indoor-outdoor cat, very well-trained. Or shall I say, WE were very well-trained. All he had to do to be let out was to sit at the door and stare it down, and we'd automatically go open it for him. His life was really sweet!
Until last week, that is. His latest victim was the cat across the street. At 14 pounds, Chico could do some damage to a measely 8 pound cat, and he did....repeatedly. I finally got a call from the distraught owner, begging me to do something with our cat. (sigh) (Why do things like this ONLY happen when Patrick's out of town!?) So on Monday night at 9pm, after hanging up the phone, I went to Walmart to buy everything we'd need to turn this hulking bully into an indoor-only cat.
After much crying and squalling like a girl, clawing at the windows, and scratching at the door, the cat's finally calming down a bit. Until this morning. I awoke this morning to the sound of something knocking on a window. I came out to the living room to find Chico sitting in the sill, but HE wasn't doing the knocking. Sitting on my vegetable box outside, just a few feet away from the window, was a robin. This robin hops along the edge of the box, then flies to the window and flutters against it. Then he'll hop around on the outer window sill, jumping up and down in front of Chico, looking at him the whole time! Chico is going insane! He's jumping at the bird, banging his head against the window, clawing and striking out at....the glass. The bully is being bullied. Nature meets out its own justice!