In the hugely popular video game Angry Birds, frustrated victims of egg theft vent their wrath by turning themselves into living bombs and blowing up their piggie tormentors. Of course, the successively more difficult levels of the game make things a little more complicated than that, as the millions who've been hooked know all too well.

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.