Jess (falconry) anklet worn by the bird, which is itself formed of another rectangular strip of leather, bound together at the ends by a grommet (usually of brass), prevented from slipping through the grommet by the knobbed end. Often, another slit is placed near the thin end of the jess cut about one inch long and running lengthwise, through which a special type of swivel is fitted, preventing the whole arrangement from twisting or tangling about itself or the bird when a leash is threaded through the other end. Their intent is more to prevent the risk of the bird deciding to
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