While the flock grazes in a field, lookouts will be posted to watch for approaching danger. They'll raise the alarm if humans approach. During the day crows fly around alone or in small groups. Often another crow will answer, and the two will fly off together. At night, crows return to a common roost where thousands of birds gather, sometimes flying as many as 80 miles back home.
Crows are most vulnerable at night, gathered in a large group, and an owl can do a lot of damage.
If crows happen upon an owl during the day they'll mob it and drive it out of the area. Speaking of humans, they used to take advantage of crows roosting habits by dynamiting them at night. Some states paid bounties for the dead crows. Crows form strong pair bonds, and both parents help raise their young, called simps. The young bird will stay with its parents for a couple of years, and help feed the next nest of simps.