A recent and developing trend in zoo design is the use of trails for animals--expanding the area available for exploration and exercise beyond the typical exhibit footprint. I believe this trend began with the invention of the 'O-line' at the National Zoo nearly 20 years ago. The O-line provided a system of transport for the Orangutans between exhibits using their natural behavior of brachiation, and maximized efficiency by utilizing vertical, rather than horizontal, space. However, over the years, the O-line has supposedly become less utilized by the Zoo due to staffing constraints. Rumor has it that because the O-line crossed above visitor pathways, keepers were posted below the O-line for safety and clean-up when in use. Recently, the Indianapolis Zoo released plans for an architecturally impressive International Orangutan Center featuring an updated O-line. It appears this system limits the animals' range over 'people space' and hopefully alleviates some of the concerns of the original National Zoo system.
We'll be discussing the Trails Trend further in the coming months.