I agree with the idea of a smaller completely enclosed area. Last year I was given some chickens and bought some mallards to raise. I learned a lot the hard way. Out of 6 Rhode Island Reds, 6 Cornish X's and 8 Mallards I have left only 1 Mallard hen. The Cornish x's of course can't live, something I learned AFTER I was given them. I have no issue with butchering my own food if i HAVE to, but I don't consider it pleasant. The Red's were taken by a fox or 2 and the Mallards went to some smurftards that call themselves hunters, but I don't find anything sporting about shooting what are basically tame ducks.
Anyway, I now have adolescents birds of numerous varieties, 17 laying hens or different breeds, some I can't yet identify, 7 Khaki Campbell ducks and 8 Mallards. I have a rather large fenced area in which I built, right in the middle, a 20 by 20 "cage" that is as impenetrable as I can build (the birds can get into their coops from the caged area). I do not intend to lose anymore birds. When I am home to be watchful I let the birds, they are all raised together by the way with no issues so far, out into the fenced area to forage. It's working great so far. I do live on the water, and at some point I expect the Mallards will fly to the creek, and then I will have to figure out how to keep the "hunters" from taking them next year. From what I have read, the Khakis probably wont fly, but if they begin to do so I will most likely clip the wings. I would rather let the mallards fly should they chose to, they are wilder, and absolutely beautiful in flight. I have been offered a few suggestions on how to protect them next season, but I am open to any ideas. If they do as the ones did last year, they will not stray very far from my pier, if they do there really is nothing I can do, we have a massive area of hunted marsh not too far away. The ducks, according to a witness, were shot right off my pier last year however. I intend to have a camera monitoring as shooting that close to my residence is illegal, not to mention the fact the area is "baited" since I feed them. I was also told I might want to get myself a stationary duck blind license and construct a blind at my pier as its also illegal to shoot with a 1000 yards of another legal blind.
Sorry, I got a bit sidetracked there, but yes, build full "cage" if its at all possible, it's the closest thing to foolproof you'll have.