When cages are manufactured, the perches are made to standard diameter and are usually made from plastic or timber. It is a good idea to replace the standard cockatiel perches with natural branches. A cockatiels perch should vary from around 0.4 and 0.18cm in diameter, this forces the cockatiels toe muscles to adjust constantly, this helps the birds feet from becoming cramped.
Trees to look for cockatiel branches are deciduous trees like willow, elm, fruit, and larch and beech trees. Do not use branches that have come from shrubs or trees with toxic branches, bark or fruit. Ensure that the branch is free from any other bird droppings from wild birds and wash it before you put it in the cage.
Cockatiels will gnaw at the bark on a branch in their cage and it can serve as a good part of the birds diet as it contains nutrients that are good for the bird. Once the cockatiel has destroyed the branch by chewing at it or it is covered in a lot of droppings, replace the branch with a new one.
The perches or branches inside the cockatiel cage should be arranged in such a way as to provide maximum freedom of movement for the bird, especially when it stretches its wings. Try to place the perches about 45cm apart so the cockatiel has to use its wings to get from one to the other. Make sure there is enough space for the bird not to always have their tail feather touching the cage. Do not put any perches above food or water containers in case its droppings fall into them causing them to become contaminated.