I've got a bit of experience with Schutzhund, and the tracking parts of it are interesting. One of the things that I learned through it are differences in scent. Wind scent, as ya'll called it, is up higher, and doesn't last as long (think hours). The ground scent is left in each place where the animal to be tracked physically touched something, and lasts much longer (think days). Tracking dogs are taught to find each and every "track" on the ground. They are taught this, because many times they are brought to the track after hours have passed, and wind scent can't be relied upon. We teach these dogs to seek the ground scent by starting out placing a treat in each track, and the dog learns to seek out each step to find a treat. They are then taught to find possible articles along the trail as well, and during a test, the dog will be penalized if it fails to indicate(sniff) each and every footstep of the person being tracked. It does, of course, get much more involved than that, but the take home message is that hunting dogs (excluding a dog that might be blood trailing wounded big game hours after it was wounded) should follow wind scent, as it is much quicker and easier for them to find. You don't want a hunting dog that stops and points or investigates every single feather or place where a bird once was, or you'd be all day covering a small field. Also, any bird that you shoot will have been wounded very recently, so the wind scent is still fresh and accurate. Hope that's clear as mud.