You mentioned Swamps, I would get areail photo's of the swamps and topo's. Compair the two, look for high ground out in the swamp, find natural funnels and travel roughts in and out of the swamps. If you spend enough time in the swamps and around the swamps I beleive you will find the sign you say you havn't seen. Even a few bucks will leave some sign in concentrated areas.