My answer depends upon species of hawk, size and gender ratio of chickens. Your location not known to me and also important but for not will assume you are in the states. Bad guys will be Red-tailed, Cooper's, Ferruginous, and Goshhawk. For me, hawks are seldom if ever after chickens as primary target, rather they are targeting smaller more natural area if they keep going to same perches each visit. Goshawk and to a lesser extent Coopers have routes they take were they fly discretely from perch to perch trying to get the jump on prey such as birds and with former mammals like squirrels.
If Red-tailed, then pen your birds.
If Cooper's. then Cooper's not a problem for me with fully adult standard sized chickens where there is at least one rooster in the mix. I have them with me all the time as they spend considerable time in barn and around property hunting songbirds as primary targets. Today I lost one juvenile chicken to an adult female Cooper's as about 30 were allowed for pen repair. During much of year the adult rooster would stop such loss but fall through midwinter that does not seem to work well. Make certain pens / coops are hawk tight.
If Ferruginous, then pen your birds. Many reported Red-tailed Hawks by people west of Mississippi River I bet are these guys.
If Goshawk, then pen birds.
Diurnal raptors ignored.
Red-shouldered and Sharp-shinned have never been a problem for me. Nor have American Kestrels.