Cuttlebones are a very important part of a bird’s diet as they provide calcium and extra trace minerals not found naturally in their diet. When a bird is molting or a hen is laying eggs their bodies use a large amount of calcium to produce new feathers and eggs. There are many health issues that can occur due to a lack of calcium in birds. One is eggbinding in female birds which can be fatal. Lack of Vitamin D3 can also cause low calcium absorption that is why it is important for your bird to get regular exposure to natural sunlight for proper Vitamin D3 absorption.