Which of the following is true?

A haggard refers to a hawk that is captured after it has fledged and is fully mature, typically one that was not raised by humans. An eyass, on the other hand, is a young hawk that has just fledged. The statement regarding a haggard being an eyass in its early life is accurate, as all haggards were young birds at one point before they matured and were captured.

Regarding the passage bird, this term refers to a wild bird that has recently fledged and is still in its first year. This classification aligns with the definition of an eyass, as both terms describe birds that are in the early stages of life after leaving the nest. Therefore, the assertion that a passage bird was once an eyass also holds true, as it describes a stage in the life cycle of that bird when it was a fledgling.

Since both statements about the relationship between haggards and eyasses, and the connection between passage birds and eyasses are accurate, the conclusion that both statements A and C are true is indeed valid. This highlights the developmental stages of hawks and the terminology used in the field of falconry to articulate these stages.