Positive identification of bats usually requires visual inspection at close range or for a bat to be held in the hand. There are many people, particularly conservationists, who would like to study bats in their natural environment without disturbing them. The task of preparing distribution maps is at present a slow and painstaking task, depending on the limited number of observers who can accurately identify bats. Most bats emerge at dusk and although some can be seen in such poor lighting conditions, most bats flying at night cannot be observed when below the horizon and against a dark background.