In their constant search for food, wild birds eat huge numbers of insects, weed seeds, and rodents. Insects, weeds, and rodents cut down the amount of food the farmer can harvest from field, garden, and orchard. The cost of fighting these pests without the help of birds would make some foods more costly to produce. The crop of an adult flicker has contained as many as 1,000 chinch bugs at a time. A nighthawk's crop contained 500 mosquitoes.
Birds gather in great numbers whenever there is a plague of insects.
Sea gulls saved the crops of the pioneer Mormons of Utah from ruin by a cricket plague. Birds also play an important part in destroying weed seeds and in scattering seeds to barren areas. One bobwhite stomach contained 10,000 pigweed seeds. That of a mourning dove contained 7,500 seeds of sorrel and 9,200 seeds of pigeon grass. These amounts represent only one meal.