The flocks comprised an important source of food, along with their agricultural production. Because of the drought, the harvest was poor to non-existant, and therefore food was scarce. Since there was no result of agriculture, the main source of food had to be focused on the animals, and the animals were leaving. They were apparently leaving rapidly enough that the people could not catch them, and in at least some (if not many) cases, were reduced to eating carrion to survive. Finally, the people are humbled and they begin to repent.