Which of the following is a requirement for an indoor falconry facility?

A requirement for an indoor falconry facility is that it must allow raptors free movement. This is essential for the physical and psychological well-being of the birds. Raptors require adequate space to fly, exercise, and perform natural behaviors. A facility designed to meet this requirement ensures that birds can stretch their wings and engage in normal activities that contribute to their overall health.

The other options do not adequately support the needs of the raptors. For instance, a concrete floor may not be necessary for every facility; various types of flooring can suffice if they provide a safe and clean environment. The height requirement is not a stipulated standard in all guidelines, as the focus should be on the overall space rather than a specific measurement. Vertical bars can also be beneficial in certain contexts, but they are not a universal requirement for indoor facilities. The emphasis is primarily on ensuring that raptors can move freely within their environment, which is crucial for their welfare.