Why are brachiating species and great apes grouped separately for cage size requirements?

The grouping of brachiating species and great apes separately for cage size requirements is rooted in their unique physical and behavioral characteristics. These species are characterized by their need for significant spatial volume, which is necessary to accommodate their natural forms of locomotion, such as swinging or brachiating through their environment. These activities require not only height and length in their enclosures to allow for safe and engaging movement but also a broader area for social interactions and play.

As such, larger cage volumes are critical for their well-being, as they support their physical health and allow them to exhibit species-specific behaviors that are integral to their welfare. This focus on size reflects an understanding of the complex needs these animals have compared to other primates or species, which may not have the same requirements for space or movement options. The distinction helps ensure that these animals receive an appropriate living environment that mimics their natural habitat as closely as possible.