The death throes of the last great ice age left a signature that we can read today.
我们可以看到上一个大冰期动物们垂死挣扎的印迹。
These giant potholes were left behind by blocks of buried ice that melted, leaving hollows that later filled with water.
大块大块的地下冰融化后留下这些巨大的坑槽，还有后来被水填充的空洞。
For thousands of years since then, they've been vital pit stops for migrating birds, the millions of cranes, geese and ducks that follow ancient routes across the plains.
从那时起，几千年来，迁徙的鸟，上百万的鹤，鹅和鸭子踏上古老的路线穿过平原，而这里是重要的旅行休息站。
These rolling hills are made of debris dumped by the retreating ice.
融化消退的冰的碎块塑造出这些起伏的群山。
lt also left rich grasslands able to support hundreds of millions of bison, vast herds drifting with the seasons, always searching for fresh grazing.
这里土质肥沃，数以百万计的野牛生活在这里，巨大的牛群随着季节迁移，不断寻找新的新的牧草。
Pronghorn antelopes are unique to North America and among the toughest creatures on the plains.
叉角羚是北美独一无二的一种羚羊，也是平原上的最顽强的物种。
Surviving year round in the open, they must cope with freezing winter temperatures and scorching summer heat.
它们一年四季都在户外生存，必须应付冬天的寒冷和夏天高温炎热。
Every spring these open spaces echo to the sounds of courting sage grouse, as males compete to win a mate.
每年春天，广阔的平原都会回荡起艾草榛鸡的求偶叫声，雄性要在此时争夺配偶。
Migrating Sandhill cranes strut and dance for their partners before heading further north towards their nesting grounds.
在向北迁移到鸟巢前，沙丘鹤会趾高气扬地走路或者跳舞来吸引异性。
Small birds breed here, after an epic journey from their winter home.
在这段如史诗般的越冬旅程中，有些幼鸟出生了。
These cliff swallows have flown thousands of miles from South America.
这些悬崖燕子是从数千英里之外的南美洲飞过来的。
