There are a variety of ways that you can scare birds away permanently. Some people use visual deterrents, such as shiny objects or scarecrows. Others use auditory deterrents, such as loud noises or ultrasonic devices. Still others use physical barriers, such as nets or fencing. And finally, some people use chemical repellents, such as bird spikes or anti-roosting products.
The best way to scare birds away will vary depending on the type of bird and the situation. For example, if you're trying to keep pigeons off your balcony, you might want to try a visual deterrent like hanging shiny objects from the railing. If you're trying to keep geese off your lawn, you might want to try an auditory deterrent like a dog whistle.
Whatever method you choose, it's important to be consistent in your efforts. Birds are smart creatures and they'll quickly catch on if they realize that there's no real threat behind your scare tactics. So make sure to keep up the good work even after the birds are gone!