You will probably want to furnish a cage with a variety of toys to keep your avian friend happy. There is a huge range available; ropes that come in various lengths and knots, acrylic shapes, mobiles, balls and bells. This is important for the more intelligent species of birds like parrots as they get bored easily.

Some feel that bird cages are inhumane, trapping a creature in a small confine, effectively jailing it. This is the root of metaphors that compare bird cages to prisons. An option that gives the birds far more freedom is a aviary, essentially a very large cage the size of a shed or even as large as a house. Aviaries are usually used by zoos and can contain several species of bird, plants, trees and insects, creating a kind of natural environment and plenty of room for the birds to fly.

 
‘Duplex’ Bird Cage/Aquarium by Constance Guisset » Yanko Design

A stylish superstructure holds a fish tank on top of a birdcage. From our POV, it’s just an odd arrangement of two very separate environments but imagine what the birds and fish are thinking.