the bats produce something very important. 会产生一种非常重要的东西

72. where they're well protected from the outside elements
    它们在此完全不受外界因素的干扰
73. and safe from predators.
    还能躲开天敌
74. And while they're up here
    它们高悬在洞穴上方时
75. the bats produce something very important.
    会产生一种非常重要的东西
76. This hundred metre high mound is made entirely of bat droppings -
    这堆100多米高的东西 全都是蝙蝠的排泄物
77. guano.
    粪便
78. Its surface is covered by a thick carpet of cockroaches,
    地面上爬满了密密麻麻的蟑螂

来自《行星地球 第一季 第四集 Planet Earth S01E04 洞穴》第 75 行