If you’ve offered your cockatiel a varied, healthy diet, taken her to the vet regularly, clipped her wings faithfully, and kept her environment clean and interesting, chances are your bird will live into old age. You may notice subtle changes in your bird’s appearance and habits as she ages. She may molt more erratically and her feathers may grow in more sparsely, or she may seem to preen herself less often.
Although little is known about the nutritional requirements of older pet birds, avian veterinarians Branson W. Ritchie and Greg J. Harrison suggest in their book Avian Medicine: Principles and Applications that older pet birds should eat a highly digestible diet that enables a bird to maintain her weight while getting lower levels of proteins, phosphorus, and sodium. They also suggest that this diet contain slightly higher levels of vitamins A, E, B12, thiamin, pyridoxine, zinc, linoleic acid, and lysine to help birds cope with the metabolic and digestive changes that come with old age.