"But so much flight in open air has its drawbacks. While a swift is eating insects with such speed, a sparrow hawk may fall on him from above. Under these circumstances the swift cannot dip down, for that would mean death by drowning. I must tell you of one such attack on my friends. They were busy catching their dinner on a vast lake one afternoon, and while I was flying about keeping an eye on the younger swifts, down came a sparrow hawk. I who had undertaken to look after the children had to act quickly even at the risk of my own life. Without an instant's hesitation I plunged and tumbled, inserting my body between the enemy and the young ones. Well, the sparrow hawk had never expected so much nerve from a member of the dove family, nor did he calculate my weight. I was at least five ounces heavier than he. He struck my tail with his talons, tore a few feathers, and thinking that he had got something he circled the air for a moment or two. Before he realized that he had only my feathers, all the swifts were safe, clinging to the bark of a tree out of anybody's reach. But the small sparrow hawk was so infuriated that he fell on me with the fury of a large one. However, his body was very small and his talons smaller, and I knew they could not pierce my feathers and my skin very far. So I accepted his challenge and tumbled up. He followed. I shot downwards; he too dived after. Then I began to rise high. He pursued as before. But those little hawks fear the upper air, and his wings lagged now. To my two wing-beats he could make but one. Seeing him hopeless and tired, I planned to teach him the lesson of his life. No sooner had I conceived than I executed my plan. I shot downwards. He plunged after. Down, down, down! The water of the lake rose towards us, higher and higher every second till it looked no farther than the width of my wing. Then I flung forward a few inches and struck a warm air current which helped me upwards. As you know, air warmed in the hollow places and valleys of mountain country has a tendency to shoot up into cooler regions. We birds look for these currents to help us when we have need to make a sudden upward flight. Now I tumbled three times, and when I looked down I found that sparrow hawk drowning in the water. He had not been able to reach the air current. After a considerable ducking, he laboriously flew ashore, and there under thick leaves hid his disgrace. That instant the swifts came out of their hiding place and flew southwards.