A duck that cannot leave needs a fence that cannot fail
Every protection decision for a Pekin starts from one fact: this breed cannot fly. A startled chicken may clear a low fence and survive the night in a tree; a Pekin runs, at a waddle, and corners easily. Snapping turtles in a pond, a mink along the bank, a raccoon at the pen corner — the duck has no exit from any of them. The enclosure has to be complete in a way a chicken run sometimes is not.
Pekins are also conspicuous. Bright white plumage shows at dusk from a long way off, which is one more reason the night house, not the yard, is where this breed's safety is decided.
Mesh, apron, and the ground line
Build the pen from hardware cloth with openings too small for a raccoon's hand, fastened firmly enough that a dog throwing its weight at the wall cannot peel a corner loose. Chicken wire will not do: it tears, and its holes admit reaching paws. Run the cloth low and finish it with an apron laid flat outward on the ground and pinned down, so a fox or dog digging at the fence line strikes mesh immediately underfoot.
Pay special attention where the pen meets any gate and where it meets the night house. Those junctions are where small gaps hide, and a mink needs very little gap. A mink in a duck pen is catastrophic precisely because the birds cannot scatter upward; seal the junctions as carefully as the walls.
The pond problem
Water is the Pekin's joy and its biggest fencing complication. A farm pond outside the secure pen invites the flock to nap on an open bank, and ducks that put themselves on water at dusk will not come in for lock-up. Predators also patrol pond edges as a matter of routine.
The workable arrangements are to fence the pond inside the secure perimeter with the same hardware cloth continued to the waterline, or to keep swimming water inside the pen in a form you control and let the ducks into the wider world only while someone is about. Either way, the evening pattern must end the same: every duck walked or herded into the night house, counted, and the door latched. Pekins herd willingly along a fence line once the routine is familiar, so build a gate and corner layout that makes that herding path natural rather than a nightly chase.
The night house and the daily look-over
The night house itself should be a small solid building or heavy pen section with a floor or a mesh skirt, a door with a real latch, and ventilation covered in hardware cloth. Bedding stays dry, because a duck that has been worried at night and sits damp and stressed is a bird whose health slides quickly.
Walk the pen each morning before letting the flock out: scratch marks at the apron, feathers outside the wire, a section of cloth bowed inward. Any duck found with wounds around the neck or back, or one that has stopped keeping up with the flock, should be seen by a veterinarian promptly.
Keeping that morning check and the evening head count in KinsLe Family Sharing means whoever is home can follow the same Pekin routine from the same shared notes.