To see how serious a matter this is we must study the food habits of birds, and we shall find that although the different species eat a large variety of food, in almost every case their natural food is something harmful to man. The large American birds, the eagles, hawks, owls and similar kinds, are called birds of prey because they feed on small birds and animals. Some of these are of the greatest benefit to the farmer, while others are altogether harmful. Another large class of birds lives almost entirely on injurious insects and this class is entitled to the fullest care and protection from the farmer. Still another class lives largely on fruits, wild or cultivated, and on seeds, which may be either the farmer's most valuable grains, or seeds of the weeds that would choke out the grain. It can not be denied that birds often do serious damage through their food habits; but the great mistake that has been made in man's treatment of birds has been in hastily deciding that if birds are seen flitting about fields of grain they are destroying the crop. A better knowledge of their food habits will lead to proper measures for destroying the harmful kinds and protecting the useful ones. Successful agriculture could hardly be practised without birds, and the benefit to man, though amounting each year to millions of dollars, can hardly be estimated in dollars and cents, since it affects so closely the size of our crops, the amount of timber saved for use in manufactures, and even the health of the people. Here again we see the careful balancing that runs through nature; how carefully each thing is adjusted to its work. Naturally the balance between birds, insects and plants would remain true, no one increasing beyond its proper amount. But when man begins to destroy certain things, and to cultivate others, this balance is seriously disturbed. The birds that destroy weed seeds being killed, weeds flourish in such vast numbers as to drive out the cultivated crops. The birds which destroy mice, moles, gophers, etc., being killed, these animals become a nuisance and cause serious losses. If insect-destroying birds are driven out, the farmer will be at the mercy of the insects unless he employs troublesome and expensive methods of getting rid of them. Certain favorable conditions cause large numbers of birds to gather in a small region and they become a pest. Very careful observation has shown that in nearly every case the favorite food of the birds is something which is not valued by man, and if this food is provided, the farm grains and fruits will not be seriously molested.