Well the chicken pen, yeah it's not the garden, but, we have a Least Weasel here that is very small. Kills chickens by chewing on their back, and as soon as there's a spot of blood the other chickens start pecking and the weasel waits and gets the leftovers.
My point is we had to use 1/2 inch hardware cloth up 2 feet and straight down into the ground 1foot with the rest of the pen in chicken wire. All to keep the little killers out.
You may need to improve your fence.