When frightened in this way, most budgies start crashing around in their cages, flying blindly into the cage’s bars without being able to stop.
There are certain things you can do in order to ensure that your pet parrot is never scared in the dark.
The cover will keep the inside of the cage dark enough and will prevent your budgie from seeing things moving outside the cage.
You should gradually make the room and the cage darker, thus giving your budgie enough time to figure out that it is safe to take a nap.