The Philadelphia Zoo is pretty small. Over the past couple of years, to help some of its residents stretch out a bit, the zoo has started installing what they call an "animal exploration trail system" - a network of corridors and tubes that critters can use to crawl, swing, and stroll between enclosures. Visitors, naturally, love it - they can watch monkeys strut and skitter above their heads. Zookeepers like it, too: it hits all the sweet spots of textbook animal enrichment, offering their charges room to roam, environmental variety, and personal choice.
"How to Tell If a Lion Is Happy" is from atlasobscura.com, published on June 15, 2016.