The hawk and eagle population ebbs and flows depending on the prey animals available... when there are many rabbits, mice, ground squirrels and other prey animals, the population grows well, then when the prey animals get reduced, they move on to greener pastures. Unfortunately, if there are chickens available they'll try for them after their more wild prey are reduced enough to make the risk worthwhile. Though teenage hawks aren't always as afraid of people as they might be when they get older. After a time, after the prey population has been depleted enough, the predators, a lot of them, foxes, raptors and others as well move on. This takes time though. It's not a short term sort of thing and your chickens are in danger absolutely. Raptors do prefer other prey not so close to people though, but they do resort to domestic prey.
Thing is, ALL raptors, Hawks, Falcons and Eagles are protected in ALL states under the Migratory Bird Treaty Act (16 USC, 703-711). These laws strictly prohibit the capture, killing, harming, or possession of hawks or owls without special permit. No permits are required to scare depredating migratory birds except for endangered or threatened species, including bald and golden eagles. REMEMBER though, scaring them means, being careful NOT to harm them in the process even by accident. Fish and Game here, and in most other states too do not mess around on this one and they DO watch for people who cross the line, word does get around too.
Offering lots of cover for our chooks has been the best defense for me. That and plenty of alert hens and when possible a good alert rooster too.