With their astonishingly intelligent bird brains, cockatoos can't stand to be cooped up in a tiny cage. They need room not only to stretch and move, but to entertain themselves by playing with toys, moving from perch to perch and finding the perfect spot to observe their favorite human.
General Guidelines
There is no doubt that the largest cage you can afford is best for a cockatoo. These intelligent birds love to play, explore and stretch their wings, and the larger the cage the happier the bird. Even if you are able to let your cockatoo out of his cage for much of the day, he'll still enjoy a large, comfortable cage. Minimum suggested cage sizes are just that, the very minimum size you should use. Whenever possible, buy a bigger cage. Also, when looking at the size consider the shape of the cage. Round cages generally offer less space for movement, so square and rectangular cages are better. If it comes down to a choice between height and width, go for more width, as long as it tall enough to be comfortable for your cockatoo.
Small Cockatoos
The smallest species of cockatoos kept as pets are typically between 12 and 14 inches tall. These include the Goffin's Cockatoo, Bare Eyed Cockatoo and Leadbeter's Cockatoo. The smallest cage suitable for these types of cockatoos is between 24-26 inches deep by 36-38 inches wide and at least 5 feet tall. Even though these are the smallest of the cockatoos, they are very agile and active, and will take advantage of even the largest of cages.
Medium Cockatoos
Mid-size cockatoos, such as the Citron Cockatoo, also known as the Lesser Sulphur Crested Cockatoo, and the Eleanora Cockatoo, known as the Medium Sulphur Crested Cockatoo, are usually between 14 and 15 inches long. A slightly larger cage than what is suitable for a small cockatoo should be used for these larger birds. A medium sized cockatoo needs a cage that is at least 29 inches deep, 46 inches wide and 6 feet tall.
Large Cockatoos
With a length sometimes exceeding 26 inches, large cockatoos need large cages just to accommodate their size. They should also have plenty of room to move around. Large cockatoos like the Moluccan Cockatoo, Umbrella Cockatoo and Greater Sulphur Crested Cockatoo should have a cage that is at least 30-36 inches deep, 48 inches wide and 6 feet high. These large birds love to climb up and down and move all around their cage and are much more content when they can get plenty of exercise.