If they're younger, they're reaching the stage where they start claiming territory. Mine decided the neighbor's dog had to go so they'd march up to the fence every day and scream at it. Then they decided to claim the cul-de-sac at the end of the driveway. I figured sooner or later they'd either get run over or actually try to get in the yard with the rottie.
I ended up adding fencing to keep them off other people's property (two sides of the area were already fenced, so I fenced in the other two sides and added a gate). I had a few incidents where they or the chickens would get out and have to be retrieved. Then they decided the fence was OK but started persecuting ANYTHING that came into the area: squirrels, small song birds, my mom's cat. One time I heard them rasing cain and then they suddenly got quiet. I see that six of them have surrounded this overgrown root-hollow that's next to the front yard. I walk up to see if they're bullying the cat and as I walk up the nearest guinea moves out of my way. At that point this rabbit leaps out of the brush and tears across they yard, with the screaming guineas in hot pursuit.
A couple months later they calmed down quite a bit, although they still "bark" back at the neighbor's dog and they chase off deer that get too close to the fence.