What does the term 'full summed' refer to in falconry?

The term 'full summed' in falconry refers to a bird that has all new feathers grown in. This condition is vital for a bird's overall health and performance, as feathers are crucial for insulation, flight capability, and general well-being. When a bird carries a full set of fresh feathers, it indicates that it has completed its molting process, which usually occurs annually or biannually. New feathers also enhance the bird's appearance and can have an impact on its hunting success and ability to thermoregulate.

In contrast, the other choices describe different states or conditions in birds that do not relate to the specific meaning of 'full summed.' For instance, a bird losing feathers pertains to molting but is the opposite of being fully feathered. Being ready to breed or in a juvenile stage focuses on the bird's reproductive or developmental status rather than its feather condition. Therefore, the definition associated with 'full summed' is specific to having an entirely renewed set of feathers, underscoring its importance in falconry practices.