Hi Hoglet
It’s possible some people are using mud to mark the hogs, but equally possible they are using some other substance which is a similar colour to mud. I know hedgehogs can be pretty clever, but I’m not sure that even they would manage to get mud in a heart shape, a V, or stripes by themselves, so it seems likely someone was doing the marking.
It is possible to learn to recognise the hogs by their natural markings, if you look very carefully at the the areas which are likely to have differences, such as their faces, skirts and the band above the skirt.
