Unless you are a home decorator, you probably have never seen one. Birdcages are the fairly useless devices that you are made to carry around during a video game or role playing game.
They can be made of woven wood or metal, the better for your pet to glare at you for locking them up to fulfill your kinky bondage fantasies. However, the bird should realize that the cage is protection against being eaten by a cat or your hungrier friends. Nowadays, people usually skip the expense of a birdcage and just let a parrot or parakeet live in their refrigerators. This has the benefit of having someone small enough to check the back of a shelf for something you might need. The refrigerator door seal also keeps the chattering and squawking from being heard all the time.