The theoretically optimal shape of a bat's wing changes with flight mode (Norberg, 1987; Norberg & Rayner, 1987) and several studies have shown this theory to be largely born out in practise (Aldridge & Rautenbach, 1987; Norberg & Rayner, 1987; Crome & Richards, 1988). For instance, bats with wings of relatively low surface area (high wing loading) that are also relatively long and thin (high aspect ratio) tend to be fast, straight fliers spending most of their flying time foraging or commuting in open areas such as pasture or above the forest canopy (Norberg & Rayner, 1987). In such bats manoeuvrability is improved by the possession of small, pointed wing tips to reduce drag. In contrast bats with wings of relatively high surface area that are also relatively short and wide with large, rounded wing tips tend to be slow, highly manoeuvrable fliers foraging in cluttered habitats such as woodland (Norberg & Rayner, 1987).