They are not protective, most flocks will not confront predators but they are very alert and watchful birds (which is why they're considered/called barnyard watchdogs)... and they are extremely quick to sound off about anything they perceive as danger.
They have to be conditioned to come back... without an established routine of being herded into the coop each evening (usually for a treat helps) they may wander off and not come back. I do not let my young Guineas start free ranging until they are 12 wks old... (they don't go outside until they are 6wks old, then they stay in the coop/pen for another 6 wks to get acclimated and imprint on the coop as home). At 12wks old they are almost full grown, they are a little smarter, more alert, more agile and better able to get away from predators.
Usually quiet at night (unless your coop is lit), but sometimes Hens will buck-wheat all night long for reasons only known to themselves. You can check out youtube for Guinea fowl sounds/calls.
Thanks!

