Crows chase hawks primarily as a defensive behavior known as "mobbing." This behavior serves to protect themselves and their young from potential predators like hawks. By chasing, dive-bombing, and making loud cawing noises, crows attempt to harass, disorient, and drive away the hawks to prevent surprise attacks on smaller birds and their nests. It also serves to alert other birds to the presence of the predator. Crows are smart and agile enough to gang up on hawks despite hawks being powerful predators, and this behavior is often observed during the breeding season when protection of their offspring is crucial. Additionally, crows may chase hawks as a way of territorial defense and sometimes potentially out of a "tough-guy" playful behavior given their intelligence. Hawks usually do not retaliate aggressively against crows because the energy cost of catching them is high, and the crows are fast and witty enough to evade capture. This mobbing behavior is not exclusive to crows; other birds like jays and even smaller birds also exhibit similar tactics against hawks and other predators. The main purpose across species remains to protect nests and reduce the threat of predation by larger birds of prey. In summary, crows chase hawks to protect their territory, nests, and young, to warn other birds of the predator's presence, and sometimes as an expression of their intelligence and social behavior.
