The labyrinth of papyrus provides food and shelter for enormous numbers of fish. These waters are clearly fertile, but did they nourish the faraway fields of Ancient Egypt? The world of papyrus is always on the move. Air sacs in the stem give it great buoyancy. Huge papyrus rafts drift on the current. These restless islands of reeds constantly redefine the channels of the waterways. It's no wonder explorers found the Sudd impenetrable. A healthy population of dangerous animals also helps maintain the Sudd's inhospitable reputation. At this time of the year, the huge swamp is, in fact, shrinking. Fish become more densely concentrated, making them easier prey. But it's not just the water that's becoming overcrowded. White-eared kob retreat into the dwindling grasslands of the Sudd during the dry season. When they were last counted, there were thought to be a million of them, one of the greatest concentrations of large animals on Earth, 1,000 per square kilometre. But the overcrowding encourages strange behaviour. The males are forced to fight over females by protecting tiny, merely symbolic, territories. But they aren't the only ones for which the White Nile is a lifeline in the dry season.


迷宫似的纸莎草丛为大量的鱼群提供了食物和栖息地。这片水域毫无疑问非常丰饶，但它的恩泽真能惠及远方的古埃及农田吗？纸莎草的世界永远都处在运动之中。纸莎草茎中的气囊为它提供了极大的浮力。巨大的纸莎草浮筏在水上载浮载沉。漂浮不定的纸莎草小岛不断改变着这片水域的水道，难怪冒险家们会认为苏德沼泽不可穿越。相当数量的危险野生动物也为维护苏德沼泽的恶名助有一臂之力。每年这个时期的大沼泽地其实都在萎缩。鱼群密密匝匝地聚集在一起，使它们更容易被捕获。但变得更加拥挤的不只是水域。白耳赤羚在旱季时会撤退到日渐萎缩的苏德草地上。人类对它们进行的最近一次估算显示它们有百万之众。它们是地球上分布密度最大的大型动物群之一，每一平方公里就有一千只。然而过度的拥挤必然催化出怪异的行为，公赤羚被迫为争夺雌性去保卫它们小到仅具有象征意义的地盘。不过除了它们，还有其他生物要在旱季中仰赖白尼罗河生存下去。