What is a "casting" in the context of hawks?

In the context of hawks, "casting" refers specifically to the process by which hawks regurgitate undigested parts of their prey, such as bones and feathers. This behavior is essential for hawks as it helps them rid their bodies of materials they cannot digest. The casting process allows hawks to maintain a healthier digestive system and ensures that they are not weighed down by undigestible matter, which could interfere with their ability to hunt effectively. Understanding casting is crucial for falconers, as it provides insights into the health and dietary habits of their birds, indicating how well the hawk is feeding and processing its food.