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
The Macmillan Field Guides to Bird Identification geographical area of coverage are included; instead only groups of species which the authors regarded as difficult to identify are covered. Each such group is given a chapter, where identification is covered discurively rather than in the abbreviated form more usually used in a field guide. The publication of the first volume (covering Britain and Ireland) was the first time that this approach had been used in a European guide The first volume is widely credited as having a major influence on improving the identification skills of birders in Britain during the 1990s. The Macmillan Field Guides to Bird Identification