Why do waterfowl migrate?
Most waterfowl are migratory. They migrate to keep away from the heavy rains and hot summers in the south and the bitter winters in the north. Waterfowl often travel long distances in search of pleasant weather. Snow geese nest in the Arctic tundra in the summer and fly south to spend the winter in Mexico. In winter, bar-headed geese migrate from India to Tibet. They fly 1,600 kilometres (1,000 miles) a day over the Himalayas, the highest mountains in the world. Flying at 3,600–4,300 metres (12,000–14,000 feet), they survive winds that blow at more than 322 kilometres per hour (200 miles per hour) and freezing temperatures. Although oxygen is low at such heights, waterfowl are capable to take in greater oxygen with every breath while flying.