As it happens with people and other living beings, if your bird eats food that is in poor condition, such as rotting or mouldy food, or the food contains unhealthy ingredients, it can get sick. You should take extra care if your pet is in the reproductive stage or is already pregnant.
If your bird hasn't been eating well for a while, in addition to not receiving the nutrients it needs on a daily basis, it may begin to lose its feathers, which can become a long-term problem. If you want your bird to stay with you for as long as possible, you must make sure it receives the food it needs.