The colony is well-defended. There are no easy pickings here. 雪雁的领地防御完善,很难让狐狸轻松下手
Sneaking up unnoticed is impossible. 出其不意的偷袭很难奏效
It's a long way to travel, but for a short period, the tundra is the ideal place for a grazer. 北极的苔原虽然路途遥远, 但仍有短短的一段时间是食草动物的天堂
Their marathon migration is almost 3,000 miles long 这场马拉松式的迁徙长达三千英里
Grass is not confined to the tropics. 草不仅生长在热带地区
Beyond the limits of the last tree, the planet is barren and ice-locked. 在最后一批树木以外的地方, 处处是冰天雪地 一片荒芜
0ut in the open, communal calving is the safest way to have young. 在毫无遮挡的草原上若想安全地繁衍 最佳方法是集体照看
one of the planet's great migrations is underway. 地球上规模最大的迁徙大军正浩浩荡荡地行进着