In the United States (at least), the term habitrail is also used to refer to any form of inter-building bridge or corridor. For example, directions to another facility might include "Yeah, take the elevator to the fifth floor, turn right, continue straight across the habitrail and walk down one flight." The usage no doubt derives from the product name used to describe the pet play tunnels described by Saige.

Those play tunnels, in fact, kick posterior if you are or if you own a small pet. :-) There may not be many things more amusing than watching three ferrets have a continuous mock battle over who gets to go which way in the habitrail, complete with quick end runs to the other opening and full-on tackling.