Know which predator attacks which weakness
An outdoor aviary is tested differently by every hunter around it. Cats climb, hook claws through mesh, and wait at corners where a bird lands. Raccoons are stronger and cleverer, prising at door edges, lifting simple latches, and reaching a long arm through any gap that fits a paw. Rats tunnel under walls and squeeze through surprisingly small holes, and snakes follow them in after eggs and chicks. Hawks and owls attack from above or slam birds against the wire in a panic, and a startled bird can injure itself even when the raptor never touches it. Proofing starts by assuming all of them will visit, usually at night.
Mesh, roof, and floor: the three surfaces that matter
Replace chicken wire, which raccoons and dogs tear easily, with welded mesh in a small gauge — openings around half an inch stop paws, beaks of predators, and most snakes, while still giving ventilation. Cover the roof fully, either solid sheeting over part of the aviary for shelter and shade, or the same welded mesh across the whole span so a hawk cannot drop in. At ground level, bury mesh down into the soil or lay a wide skirt of mesh flat outward from the base and weight it with soil or pavers, so digging animals meet wire wherever they start. Set the floor edge on a concrete strip where the ground is soft.
Doors, latches, and the gap you forget
Most break-ins happen at the door, not the walls. Fit a double-door entry porch, even a small one, so one door is always closed between you and the birds — it stops escapes and blocks a cat slipping in behind you. Use latches a raccoon cannot flip: bolt-style fasteners with a clip or padlock, never a simple hook-and-eye. Walk the whole structure slowly and check the seams where panels meet, the corners around perches, and any place a feed hatch or nest box joins the frame. If your fingertip fits through a gap, a rat's head or a raccoon's fingers probably do too.
Do not forget the threat that arrives on the wind
Not every danger claws or digs. Wild birds landing on the aviary roof can pass droppings, parasites, and disease through wide mesh to the birds below, which is why a solid roof section or a second offset layer of fine mesh over the top is worth adding where wild birds gather heavily. Food and water containers set against the outer wall invite this contact, so move them inward. Wind-blown debris and falling branches after storms can also tear a panel or lever a corner open overnight, so add a full perimeter walk to your routine after any severe weather, before you assume the structure is still sound.
Habits that keep the proofing working
Remove spilled seed from outside the aviary each evening, because a nightly food trail trains rats and raccoons to patrol your birds. Keep shrubs and stacked timber away from the walls so predators have no hidden approach or climbing launch. Lock nest boxes and feed doors on the same round every night, and inspect mesh monthly for rust, pulled staples, and gnawed timber, repairing small damage before it becomes an entrance. Inside, give birds a solid sheltered corner and dense cover so a hawk shadow causes a retreat, not a blind panic flight. If the structure needs rebuilding rather than patching, KinsLe's Pet Services Directory can connect you with local builders and tradespeople who understand aviary work.