When a raptor is described as keen, what does this mean?

When a raptor is described as keen, it indicates that the bird is in a state of readiness to hunt and is sharp-set, meaning it is alert, focused, and eager to pursue prey. This state generally reflects a combination of physical readiness and mental sharpness, making the bird highly effective in hunting scenarios. Keen raptors are typically attentive to their surroundings and exhibit behaviors that indicate they are prepared to engage in hunting activities.

Understanding this term is essential for falconers, as recognizing a bird's keen state can help them determine the right time for training or hunting. Other terms in the question relate to the bird's health or aggression, but they do not convey the sense of eagerness and readiness that "keen" embodies.