I’ve heard of many different fad diets over the years but ISTM a diet of voles would be a PITA. Takes a dozen to make a single decent burrito.
I like to say that our squirrels are living the good life because their ancestors had the foresight to plant a lot of oak trees.
There was one particular squirrel back in the 18th century who always carried a few acorns in his pocket, to plant some wherever he went, so that his descendants would never be short of ship wood nuts.
It’s not unlikely that the methane is being used to power the physical plant.
Actually, I feed them instead so they don’t disturb my lawn, with little feed boxes distributed around the property.
When I had a compost heap, I also had a cat, who was rather skilled in the field of rodent control..
When he died, my one dog took on the rôle but by then I had also set up a vermiculture setup (aka worm farm) which effectively composted kitchen waste that my wife ineffectively used… despite her imterest in plants.
Can’t win them all.
Many years ago, when I forst bought a house and knew nothing about composting, I just piled the grass clippings in a corner of the yard and occasionally tossed assorted garbage inside the pile. I was surprised to see that two years deep in the pile was intact clippings and unchanged greatfruit skins. (Now I have the internet to tell me what I’m doing wrong)