Decoys are still used for hunting ducks, but they are now also used for ornithological research, in which the birds are released after capture.
As finally developed, the decoy consisted of a pool of water, leading from which are from one to eight curved, tapered, water-filled ditches.
[5] When a sufficient number have gathered, they are encouraged to swim down one of the pipes leading from the pool, where they are trapped.
At Swanpool near Lincoln, cropmarks revealed in aerial photographs show the outlines of a decoy.
[21] In his diaries, Sir William Brereton, 1st Baronet describes a "coy" in County Wexford as early as 1635.
[24] On the North Frisian Islands, decoys originally served as a pastime for sea captains and ships' officers during wintertime.
Later the ponds were also used to trap great numbers of wild ducks for commercial purposes.