Because crows see other larger birds as intruders into their territory. Few issues now. 1. read more
Crows don’t follow - they mob (Mobbing) and harass the intruders by forming an attack group - objectives are to safeguard their territory, food, chicks or, even to snatch food. Large grayish Birds that you see crows mobbing in India are not Eagles, but generally Kites- either Black Kites or, Black-Eared Kites. Eagles are not that common in India. read more
Crows are attracted to eagles for protection as magpies will also hang with crows. I have often seen crows friendly and hanging with bald eagles and have a shot of one hanging with a bald eagle after i witnessed it in a run in with a snowy owl. I have seen crows mob owls but always seem to have a symbiotic relationship with eagles. read more
The crows are reacting to the potential threat the hawk poses as a predator, to the adult crows and their offspring. The mobbing often serves to harass the hawk into leaving the area. Occasionally a mobbed hawk will turn the tables and attack and kill a crow. read more