Yeah. The pepper thing is an old wives' tale. Not a grain of truth to it.
ddawn is absolutely correct on all counts. You saw one snake skin, but you could have many more than one lurking around. Last year someone posted about catching an egg eating snake. The poster thought they were dealing with one snake, but it turns out they had something like 7 huge snakes when they were all done.
Increase your flock's protein intake. Put them on a grower feed for a couple weeks and have oyster shells available to make up for the calcium that is lacking in grower formulas. BOSS and cat food are good sources of protein, too.