A jerk cord is a device used in hunting, particularly in waterfowl hunting, to remotely operate a decoy, making it appear more lifelike and realistic to attract game. The jerk cord system typically consists of a long, flexible cord attached to one or more decoys, which can be pulled by the hunter from a concealed position to create subtle, lifelike movements in the decoys, such as ripples or the motion of swimming.

By creating movement, jerk cords mimic the behavior of real birds and enhance the realism of a decoy spread, helping to draw in passing waterfowl like ducks and geese. This added realism increases the chances of attracting birds to land in the hunting area, as waterfowl are more likely to approach a spread that looks natural and active, rather than a static, unmoving decoy setup.

Jerk cords are particularly useful in still water or calm conditions, where the absence of natural wind or wave action may make decoys appear too stationary. The jerk cord can be manually or mechanically operated, allowing the hunter to subtly manipulate the decoys without exposing themselves, making it an effective and versatile tool in waterfowl hunting.