Anatomically, a bird’s ‘hand’ is its outer wing, that is, everything past the wing bend or carpal joint, just as the inner wing is referred to as the bird’s ‘arm’. The term is often heard in connection with the outer wing of raptors, as many of them have primary feathers that extend from the wing in a shape that resembles the fingers of a hand. In fact when it comes to raptors, the hand can be one of the most visible aids to identifying the species you’ve just spotted, and its relative age, with juveniles tending to have narrower hands than adults of the same species. The general shape of the hand is a fairly good guide to the type of raptor you are looking at, with falcons, for example, usually having pointed hands, harriers having blunt ones with short fingers, and eagles and vultures possessing broad hands with prominent fingers. The length of these primaries can also aid with differentiating between similar species; for example, the longer seventh finger of the Spotted Eagle helps to separate it from the Lesser Spotted Eagle where their ranges overlap. The number of fingers on the hand can help, too.