As I was doing the dishes one winter's day, I saw an orange tabby in the tree outside the kitchen window, stalking a magpie. Just as he was doing his pre-pounce butt-wiggle, another magpie swooped down and grabbed the cat's tail. The cat whipped around (nearly falling off of the narrow branch), but the tail-squeezing magpie had already retreated to a higher branch. So the cat began stalking the second magpie, while the first magpie hopped along the branch behind the cat, waiting for the butt-wiggle-- squeeze, spin, escape, bird snickers, rising feline fury. Rinse, repeat.
This went on until it was too dark to see any more. I don't know who won, but that cat was LIVID.