Eggs hatch in about 18 days, and the young fledge in just over a month. In the nest the young depend on their parents and older siblings for food. Crows roost in large numbers to protect themselves from predators. Enemies include great horned owls, red-tailed hawks, raccoons and opossums. By gathering together, crows find safety in numbers.
Crows have a cooperative defense behavior known as mobbing.
If one crow sees a predator, it will give an assembly call. Every crow within earshot will quickly fly to the source and attack the predator. If a crow has already been attacked, it will give a distress call, summoning other crows to its defense. Crows are also highly social. They have up to 25 different calls and seem to use them all.