A Pine marten will hunt in the day especally if it has young, once they find where the food is they will keep comming back till non left. Weasles, Stoats and ferrets all do the same and will take prey, 3 and 4 times there size, i hope i hav`nt put you off, a fully enclosed run with mesh buried as deep as you can shoulds be ok, don`t forget Martens can climb--------Fred