Personally, I don't really think the magic to a good tracking dog is in the method you use to start. Your goal is to use a method that clearly communicates to your dog that he/she follows the aged scent of the person on the start article. So, how does your dog learn other sports? What really rewards them? Some dogs don't learn with food, only toys. Some dogs need lots of food rewards to get through their learning process and others need very little food to put the pieces together.
The magic of tracking lies in the dog trainer at the end of the line. Dog training is all about communicating/teaching your dog something when you and the dog don't speak the same language. And two things make tracking uniquely challenging to train: 1) you are asking your dog to use a skill they have that far exceeds our own; and 2) you are asking the dog to lead the way through the test.
We as humans can really only guess at how our dogs really do scent work. We have a good idea on how they use scent based on how the dog works a track. And watching is the best way to learn how your dog works scenting. If the track goes along the top of the hill, what does the dog do? If the track goes down a hill, what happens? If the wind is blowing, what happens? Be a student of your dog and you will learn by their behavior how they work scent.
Tracking is one of the few dog venues where the dog leads. You don't know where the track is at a test (it is "blind"), so you must rely completely on the dog to get you from the start flag to the final glove. Since my very young dogs are tracking, I've had a lot of people say to me, "Oh I'll do tracking when my dog is older because it's an easier sport on their body."
Yes, tracking is not as physically demanding as agility; it is an endurance sport versus a sprint sport. But I always have a word of reminder for folks who take older obedience and agility-trained dogs out to start tracking. Our older dogs have always worked at the direction of their handler. But tracking requires the dog to lead and the handler to follow. Many older, well-titled dogs struggle with green handlers because the dog is looking for the handler to guide them.
Quite frankly, this is why Ian doesn't have a tracking title yet. Ian really enjoys tracking, and he learned straight lines very quickly. He had a ball out there, wagging his tail and bouncing and barking. However, when I started turns, everything fell apart. Ian would lose the scent and then come back to my side and happily look up at me wagging his tail saying, "Ok, that was fun. Now I have no idea what to do, so can you help me?"
So with that background, I will now answer the question. Personally, I start with food on a regular track. I prefer a low value food reward (I use kibble/dog food), so that it's easy to fade as the dog learns the game. I start with a 35 yard track. I put the start article at the flag and then step off on the track in a normal stride. After I plant my third step, I lift my heel from my second step and drop a piece of kibble right into the footprint of my second step. In this manner, I put kibble in every other footstep for the first 10 yards; every third footstep for the next 10 yards and every fourth footstep for the final 10 yards. Then I put no kibble for 5 yards, but I put a jackpot of kibble in the end article.
I like to drop one piece of kibble into the footstep itself, because I want the dog to have it's nose in the footstep/scent when it's rewarded. I spread the rewards apart to pull the dog down the track. I want the jackpot in the end article (not on top or below the article), because I don't want the dog to self reward. Eventually I want to transfer the value of the reward to the article itself and away from the food.
I may run two of these 35 yard tracks in one session. The next day I will follow up with very similar tracks, but with kibble starting every three steps instead of every two steps. My goal is to eliminate the food as quickly as possible. So I stretch out the spacing between kibble drops very quickly to every 5 yards, then every 10 yards then every 20 yards and eliminate them except in articles.
You as the dog trainer must read your dog to see when there is too much food and it becomes a distraction, or when your dog doesn't really get the game and needs the food help. If the dog is tracking along and then does a 180 and comes back to a food drop, that's a big clue you need to eliminate your food drops or spread them farther apart. If the dog is completely shutting down and wandering off, you may need a higher value food or put the spacing closer.
And now I return to where I started: the most important part of teaching your dog to track is not how many pieces of kibble are on the track. The most important part is that you teach your dog to pull you down the track. I start my dog on a 6 foot leash. If my dog is nose down on the track in my footsteps, I walk behind her. The instant my dog goes off that track, I stop. I hold my ground until the dog's nose drops back onto the track and then I move forward.
And here's another very valuable tracking tip: keep your mouth shut. At the very beginning, if my dog is tracking I may quietly say "good track" or "good dog." However, when my dog goes off the track, I simply stop and wait them out. I let the dog figure out his/her own problems; so I let the dog figure out how to get back on the track where the food reward is without verbal help from me.
A dog investigating off the track is normal. They are problem solving. They are figuring out where the track/scent is and where it is not. You aid this problem solving by not going with them when they are off the track. I cannot stress this step enough. One of the biggest mistakes I see most people make in tracking is to continue to walk forward when their dog is off the track.
When my dog is confident on short tracks without food, I'll transfer to a 20 ft. line with 10 ft. marked on it. I won't get more than 10 ft. behind her until she is very confident on much longer tracks. I will probably leave her on this 20 ft. line while I teach turns and slowly allow the dog more distance on the line as she gets more confident. Once they are confident on turns and I'm moving out to the end of the 20 ft. line, I'll transition to my 40 ft. line and work 20 ft. behind the dog. This is the same line I use in tests.
Once my dog is working confidently on short tracks with turns, I'll age the tracks up to 2 hours in 20-30 minute increments. I will not add any length to the track while I'm aging; I teach one component at a time. When the dog can do 2 hours, I will then start "ping ponging" the age of my training tracks between 45 minutes and 2 hours. This is the typical range for a TD test track, so I want my dog working randomly in this range.
Finally, I work length of track. When I feel I have a well-trained dog, I'll ask for help from others to lay me blind tracks. After successfully running three blind tracks, I'll call a judge and set a certification time.
How long will all this take? It all depends on the dog and the handler. Devon was my first certified dog. It took us 5 months to get from start to certification. However, Page ran a 2.5 hour old blind track (the first time she tracked someone other than me) at 16 weeks, just 7 weeks after I brought her home. Page certified easily at 19 weeks. I believe Devon and Page are equally talented tracking dogs; the difference in the time frame had everything to do with my education in tracking. I know a lot more than I did 3 years ago!