Sparrows have been infamous for eating crops in the harvest time. They are even listed as one of the "four pests"(mouse, sparrow, fly, mosquito).

In fact, sparrows are omnivorous birds. In winter and early spring, sparrows eat weed seeds and wild gramineous plants, as well as the food people wasted. In summer and autumn, they feed themselves by the seeds of gramineous plants. In the brood time, they eat the pests which are harmful for the gramineous plants, mainly lepidoptera pests. Therefore, sparrows are not that harmful. In summer and autumn, the mature seeds are reaped soon and don't stay long in the field.

Meanwhile, sparrows, as a kind of wild animal in large quantities, play an important role in the natural ecology. If their quantity drops suddenly, the food chain and even other creatures will be influenced.