the distance between bali and lombok is only about 35 kilometers. surprisingly, the distributions of many bird species observe the line, because many birds do not cross even the smallest stretches of open ocean water. some bats have distributions that cross the wallace line, but other mammals are generally limited to one side or the other; an exception is the crab-eating macaque. other groups of plants and animals show differing patterns, but the overall pattern is striking and reasonably consistent.