Where I am in central wisconsin, we have a lot of raptors in the area.. I'd see at least one just about every other day.
Our free range flock has very few problems with raptor losses, despite this. The flock is roughly 100 birds currently.
I think this comes down to a few factors.
- Few/poor hunting perches around the chicken yard. On three sides there are no significant trees for over 100 yards. Edit to add: The 4th side still has about 30 yards between the birds and the treeline. They don't like that side of the yard too much.
- Good cover for the chickens. Lots of low brush, old truck toppers, all kinds of things to hide under when the alarm is raised.
- Several experienced roosters, and some new ones learning from their example. They're always on the lookout for anything dangerous
- Suspicious birds. All of our chickens are quite distrustful of moving shadows, even ours.
When a raptor does pass overhead, at least one bird will raise the alarm, and every bird in the flock runs straight for the nearest cover.
Once under cover, they stay there for some time. In the winter, they stay under cover most of the time, and much closer to cover if they do leave it.
Generally no more than 3 yards from cover in winter.
We do still occasionally lose birds to raptors, but over the last 4 years raccoons and foxes have been far more problematic than raptors, despite the raptor numbers.