What is being foreshadowed in the following passage from the birds?: " covering his head with his arms, he ran toward the cottage. They kept coming at him from the air, silence save for the beating wings... Each stab of a swooping beak tore his flesh. If only he could keep them from his eyes... They had not learned yet how to cling to a shoulder, how to rip clothing, how to dive in mass upon the head, upon he body."