i wouldnt trust on the woodknocking too much, alot of humans do that to see if bf will respond. easy way to tell if it is a bf, is the deep ness of the sound and how it resounds across the woods,a nd such. Think they are fricking strong and can slam wood pretty hard alot harder than any of us. also in my resaerch i am positve they migrate only a little, not like whales and such , but like the native americans who had a summer camp and a winter camp, the reason is to let teh food in the area replenish it self and also to keep the village from disease. i think bfs have a migration range of five hundred square miles on just how fast they travel, their family units, their size. later all