Which condition must raptor housing facilities meet for flying or movement?

For raptor housing facilities, it is essential to provide space that allows for free flight if the birds are untethered. This requirement ensures that raptors can engage in natural behaviors, which is critical for their physical and mental well-being. Adequate space enables them to exercise, build strength, and maintain the muscle tone necessary for hunting and flying.

Providing a space for free flight contributes to the overall health of the raptors, enabling them to express natural flight patterns and behaviors that are key to their development and rehabilitation. It mimics their natural environment more closely and helps in reducing stress and behavioral issues that can arise from confinement.

In contrast, the other options do not fulfill the necessary conditions for raptor welfare. Space only for tethered movement limits their ability to fly freely, while the absence of specific space requirements does not sufficiently prioritize the needs of the birds. Only requiring horizontal space neglects the importance of vertical flying space, which is crucial for many raptor species. Overall, the condition that mandates space for free flight aligns with best practices in raptor care and falconry.