Think like the animals trying to get in
The predators that threaten an outdoor tortoise are not exotic: raccoons with strong, clever hands; neighborhood dogs with digging power; foxes and coyotes in many suburbs; crows, ravens, and hawks that take small tortoises from above; and rats, which chew. Each one attacks a different weakness, so walk the enclosure and audit it three ways — what could come over the top, what could come under the wall, and what could reach or tear through the sides. A design that defeats all three routes, with a secure night refuge as the last layer, is what predator-proof actually means.
Over the top: a real roof, not a suggestion
Fit a framed cover of welded mesh or hardware cloth that spans the whole enclosure and latches down — raccoons learn to lift unlatched lids and can work simple hooks, so use latches a thumb must operate. Walls alone do not stop climbers: a raccoon scales a wooden fence in seconds, and a hawk does not care about walls at all. Small tortoises, whose shells are still soft enough for a crow to damage, need the cover most. Choose mesh with openings small enough that a raccoon cannot reach a paw through and grab — half-inch hardware cloth is the keeper's standard — and make sure the frame is rigid enough that a dog leaning on it cannot bow it into the enclosure.
Under the wall: bury the barrier
Digging defeats more enclosures than climbing does. Bury hardware cloth vertically at least a foot down around the inside or outside of the perimeter, or lay a horizontal mesh apron flat on the ground extending outward from the base and pinned under soil and turf, so anything digging at the wall hits mesh immediately. This barrier works in both directions: many tortoises are determined diggers themselves, and the same skirt that keeps a fox out keeps a sulcata from tunneling into the neighbor's yard. Check gate bottoms and corners, where gaps concentrate, and re-check after heavy rain shifts soil.
Through the sides: solid lower walls, honest materials
Make the lower portion of the walls solid — wood, block, or metal — to a height a dog cannot see over easily, because a tortoise that predators cannot see draws less determined effort. Replace chicken wire anywhere it appears: it keeps birds in a coop but tears under a raccoon's hands and its wide hexagons let paws and muzzles through. Doors and hatches get two fasteners, not one. Inside, give the tortoise a lockable night house or solid hide box; even inside a good enclosure, a shut hide at dusk is the layer that saves an animal when something does get in — and in raccoon country, bringing small tortoises indoors at night outright is the choice many keepers make.
Check the proofing like a keeper, not an owner
Walk the perimeter monthly and after storms, pushing at mesh, testing latches, and looking for fresh digging — yours or a visitor's. Motion-sensor lights and clearing brush that gives predators cover near the fence both reduce attempts. And plan for the failure you hope never comes: a tortoise that escapes or is carried off is findable in the first hours if neighbors know to look, which is why KinsLe's Lost Pet Alert System matters for tortoise keepers — one alert reaches nearby members within miles, and a finder who spots her can message you directly instead of guessing who she belongs to.