Crows like to live in groups with strong clustering, and a group can reach tens of thousands. Living in groups in forests or fields, they are forest and grassland birds, mainly foraging on the ground, and their gait is stable. Except for a few species, they often nest in groups and wander in groups in autumn and winter. Complex behavior, showing strong intelligence and social activity ability. Generally fierce and aggressive, they often prey on eggs and chicks in waterfowl and wading nests. In addition, because they like to rot and peck at agricultural waste, they can eliminate the pollution of animal carcasses and purify the environment.