Usually four greenish eggs with splotches are laid and incubated for 19 days by both parents. Chicks hatch in April. Young are cared for by both parents and grow quickly. They stay with adults for a year or more, often helping to protect and feed the next year's brood. Scientists have discovered that adults with helpers produce more young than parents without helpers.
Some crows have a second brood in the same year.
Crows defend a territory from other crows only during the nesting season. The rest of the year, they prefer to flock up with other crows for at least part of the day, often roosting in huge groups at night. If you watch at dusk, you can see them fly in long lines towards their night roost. These communal roosts may have some benefits, but they also have drawbacks. Roosting with other birds may protect them by sheer numbers from predators as there are more birds to be on the alert.