I've just put pavers around the perimeter, except where it butts onto concrete. Our predators are mostly cats, hawks and owls, so it works for those. I do plan to put down a hardware cloth apron, as raccoons pass through our area on rare occasions.
If bird flu keeps heading west, I'll need to...
I have two. They're pretty sturdy, work well and are easy to assemble, but definitely require additional predator protection, depending on predators. Rosemarythyme's suggestions make sense.