For what it's worth, the night pen I am building will be all half inch hardware cloth. Sides 4 ft. high, width 4 ft., length about 9 ft. That is just Little Fort Knox. Daytimes we will be rotationally foraging with temporary fence that's 3 ft. high with netting across the top. (The ducks are coming because last year, the slugs made short work of too many plants.
Then there were the Japanese beetles and the potato beetles.
) I may need to invest in more infrastructure, depending on predator pressure. We have all kinds of predators in the area, including domestic dogs and cats. But I believe we can thwart them. Much of my work is in the garden, so I will be the primary guard animal. Grrr!!!!!!!
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I dug +- 10 inch trenches around 3 sides of the pen area, and set in 4"x8"x16" concrete blocks on their 4" sides (depth 8") to deter digging, then decided to go ahead and line the bottom of the pen with hardware cloth anyway, which will be under a few inches of sand (drainage, protect feet), with bedding on top.
Again, this is the secure night pen - rather small, and just an extension of the Duck Inn. To keep the duck house dry, I will have the water out in the pen area.
By the way, I am planning for runner ducks, tall and fairly light (3.5 to 4 pounds, I am told). That is one reason I have the 4ft high pen - I had read runners could be as tall as 34 inches. I think I will end up with birds closer to 28 inches (females, not necessarily show quality).
Enjoy!