What types of barriers can zoos use to keep birds inside aviaries?

Zoos utilize several methods to contain birds within aviaries while maintaining visibility for the public:

• Wire Mesh: This is the most common barrier used for the sides and roofs of enclosures.12
• Piano Wire: A less visible alternative to standard mesh, this involves placing wires vertically at intervals of one-half to one inch.2
• Glass: While sometimes used, glass must be positioned very carefully to avoid unwanted reflections, which can be problematic as many birds may injure themselves by flying into it.12
• Lighting Effects: Birds can be effectively confined by brightly lighting specific areas of the enclosure while keeping the public viewing area dark.2
• Air-lock Doors: In "walk-through" aviaries, where birds have free range of a large space, visitors enter through air-lock type doors to prevent escapes.2

While wire is generally preferred for safety, zoos must balance these containment needs with the welfare of the birds, often providing large, naturalistic environments to ensure the animals can exercise sufficiently.12