In certain rural parts of China, the police use geese to guard the police station, not dogs! If you have ever heard a flock of geese make a racket, you will understand why. Once they get going, it is very hard to make them stop. They are an alarm system on their own—and you can't cut the wires! You can still distract a dog by offering it a juicy piece of steak, but if you throw something at a goose, it is likely to make an even bigger noise.
Why are geese such brilliant guardians? First, they are very territorial and don't like it when any stranger comes into their territory. They perceive their owners to be part of their flock and can distinguish between them and strangers.
Geese, like all birds, have excellent eyesight. Human eyes have three different color sensors that combine an image that is sent to our brains. Birds have four—the fourth one being ultraviolet. They can see better at a distance and close-up than humans can.
Geese are fairly easy and cost-effective to take care of. They are quite content with some cracked corn and grass to graze on. The barnyard variety makes the best 'guard dogs' as they are noisier than the other varieties.