Jess (falconry) chase something it shouldn't, and less to keep the bird from getting away, as falconry birds are routinely (and as part of the sport) set free—the bond between bird and falconer serves as a much better leash than any leather or rope ever will; however, it is not always desirable that a bird be able to take flight at its own whim, and both on the glove and on the perch, jesses help ensure this. During hunting season (small game season for North American falconers), jesses are generally worn all season in the mews, and are often removed for the
Falconry are kept for purposes of rehabilitation (for which a licence must still be held), and in such circumstances it may be possible for a competent falconer to teach a bird to hunt and kill wild quarry, as part of its regime of rehabilitation to good health and a fit state to be released into the wild. In New Zealand, falconry was formally legalised for one species only, the swamp/Australasian harrier ("Circus approximans") in 2011. This was only possible with over 25 years of effort from both Wingspan National Bird of Prey Centre and The Raptor Association of New Zealand (RANZ).