Lost a guinea

[Wlorraine]

I bought 6 guineas. I lost one before he could go outside. This week the neighbors puppy a pit bull by the way kill one now I only have 4. My guinea don't leave the back yard very often but stay with the chickens and ducks and seem very happy that way. But the loudest guinea does leave the back yard occasionally. A few days ago it cost him his life. I got the guineas to keep the chicken snakes away. But after this one guinea death there was a snake in the chicken coop this morning. I don't get it. Does losing the leader of the pack make the others noneffective? Will they new flock members? What do I do?