Real-life birds don't have quite that kind of firepower, but, as I discovered as I researched my National Geographic book Angry Birds: 50 True Stories of the Fed Up, Feathered, and Furious, they've evolved an amazing array of ways to display their ire. Mockingbirds dive-bombing intruders, bellbirds ringing their nests with paralyzed poisonous caterpillars, eagles attacking hang gliders, frigatebirds pirating food from weaker birds—the variations of avian aggression seem endless.

And you probably don't even want to hear about baby fulmars, who projectile-vomit oily gunk to defend themselves against predators. (What's that bird? See National Geographic's Backyard Birding guide.)

Birds don't have to be big and powerful to show anger. Even sparrows—small, shy, brownish birds that tend to skulk in