I let my first trios of pullets do that too, and they were predated too. Roosting in trees - or more accurately, being able to fly down and start foraging in first light, pre dawn - is the problem. Getting them in at night is the key to successful free ranging in my experience.they started to sleep in the trees soon after they bought them. They lost all chickens within 2 years
I didn't initially, and lost birds to predators. Since I've had roos I've hardly lost any - and it was the roos who sustained the injuries on the learning curve. So I think it makes a big difference.They didn’t have a rooster, not sure if that would have made much difference
That's the point. The roos have their heads up and are looking around for danger the whole time, while the hens have their heads down and their minds focussed on finding food. A roo calls, and depending on the type of the alarm, the hens may scatter and hide in a flash, or just look up and around, or move closer to the nearest roo, or all come together in a tight flock with roos round the edges. It is far more sophisticated than those without roos, or who don't free range much, realize.a rooster as the first chicken to sound the alarm when something is wrong