I would like to add a few things to this that I have observed.
First as many know a shot with no exit hole will not look so great as far as blood on the ground is concerned but this in NO WAY means you did not kill the animal. It just means the blood is filling up in the chest.
This next one is a big one in my opinion.
If you get a shot and can see a bunch of arrow hanging out of the side of the animal runs off, DO NOT DESPAIR! You may not have an exit hole, but if you hit the animal in the right spot the animal will die weather there is any blood on the ground or not.
Here is an example. The last buck I shot was quartering away at a steep angle. I hit him bit more forward than I would have liked but not much. As he ran off I could see over half of my arrow sticking out and realized I likely did not have an exit hole and that there would likely be little blood on the ground.
Most of the time I like to be right, but this was not one of those times! When I began tracking I found little blood at all. After 150 yards it just stopped. I began to panick and did the grid searching thing to no avail. This was the morning after I made the shot. Then I had to go to work. One thing that bothered me was that I recovered no part of the arrow. Knowing that they normally break it off while running away, I went back and started at the last blood. On my hands and knees I eventually found a little more. This took hours. I tracked that buck for a total of like 26 yes 26 hours over a three day period after work and eventually found the back half of the arrow. Not fifty yards after that I found the buck. Well I found what was left. Coyotes did a number on him but at least I had closure. If you track an animal and do not find the arrow then you need to keep looking. The animal will always break the arrow off or die or both. The animal may live and continue to run, but the arrow will not and will remain stationary. Find the arrow and go from there.
When you hit an animal be confident in your abilities and take the situation into consideration and see it through as best as you can. The rewards are big.
On another note, I am writting an article that I will send to TBM or PBS. It is an interview with a black tracker in Africa. One of the few that could understand enough english to do the interview. He also happend to be the absolute best tracker I have ever witnessed in my life. Trust me. The native black trackers over there would make the best trackers in the U.S. look like beginners. I never felt more useless in the outdoors than the first time I watched these guys unravel a difficult track in amazingly difficult conditions. Let me just say that I watched one track a springbok I had shot for over a mile over rock terrain with absolutely no blood.
There are things to learn from these guys, and I feel this interview will be very beneficial to those who have not actually hunted in Africa and learned from these masters.