It measures around a hundred yards across, and its shape is anything but accidental: four semicircular promontories jut inward from the centre of each side, and a circular island once sat at its heart. This is the ghost of a duck decoy, a piece of engineered wildfowling infrastructure that has not functioned, as far as anyone can tell, for well over two centuries.

Duck decoys of this kind were a Dutch import, widely adopted by English and Irish estates from the seventeenth century onward. The basic principle involved luring wildfowl onto a specially shaped pond, then funnelling them along narrow netted channels called pipes, where they could be caught in quantity. The geometry of the Doneraile pond, with its promontories and possible pipe extending from the eastern corner, follows this design closely. A writer named Smith, recording what he saw in 1750, described a fine decoy at Doneraile, and the pond's similarity to the Beaulieu decoy near Drogheda, which was constructed around 1730, suggests a broadly contemporary origin within the demesne of Doneraile Court. By the time the Ordnance Survey mapped the area at six inches to the mile in 1842, the feature had already vanished beneath dense woodland and was not recorded. By the late nineteenth century, local memory of it had faded entirely.

The area is still known locally as The Decoy Wood, which is its own kind of preservation. The outline of the pond remains visible on the ground despite being dry, a faint architectural signature left by something that was once purposeful and productive, then forgotten, and now legible again only if you know what you are looking for.