Critters

 

Everyone suffers at some point with unwanted intruders.
I have had rats, magpies, jackdaws, egg thieves (suspected workmen at neighbouring properties).
General tidyness can put off most intruders, keep feeders inside and hang them up.  
Close the huts at night.
Only feed in the morning, so the hens are less likely to scatter or leave waste.
Regularly check the condition of fences and repair as required.
Rats
Rats have routines and will ignore or mistrust any additions to their area, so poisons and traps can be unsuccessful
If you bait a trap but don't set it for a few days then the rat will accept it as scenery and can be caught later.
If you regularly move things around and try and disrupt them as much as possible, 
then everything is always new and they are more easily caught out.