Guinea Fowl are like watchdogs and have incremental levels of alert calls. I have developed a feel for their calls. Immature guineas just like to hear themselves squawk and confuse issues. When the roosters respond along with the guineas and then the hens join in it is usually the real thing. Not always. Sometimes an airplane or helicopter will set them off.

Soaring birds are different than birds that have to flap continuously to stay aloft. Some birds just flit from tree to tree. Guineas and chickens pay close attention to such things.