March 21, 2017
By Dr. Grant Woods
Most of us tune our bows and practice shooting all summer in anticipation of getting a shot at a good buck. We invest thousands of dollars and countless hours in hopes of having a great experience! But all our work is for naught if we don't understand why paper cuts kill deer.
Almost all deer killed by archery equipment die as the result of massive hemorrhaging, or blood loss. Hunters often ask, "How much blood must a deer lose before it dies?" This is a very difficult question to answer given the number of variables such as body size and gender of the deer, physical condition, level of excitement when shot, etc.
A Lot to Lose
The blood volume of most animals is approximately 7 percent of body weight. So, a 200-pound buck should have about 14 pounds of blood, or 224 ounces. (A fluid ounce of blood weighs approximately 1.1 weight ounces).
A deer must lose about a third of its blood to go into a state of shock or die. So, in our example, the buck would need to lose around 74 ounces of blood. A deer can "lose" this blood internally if the arrow doesn't pass through, or if the wound is such that it pools or collects in the body cavity. Deer with such wounds can be difficult to trail unless they fall within sight of the hunter or a tracking dog is used.
There are approximately 600 drops of liquid per ounce. Obviously, this is highly variable and depends on the drop size, thickness of the blood, etc. For the sake of this illustration, let's be conservative and reduce this to 400 drops of blood per ounce. If a buck needs to lose 74 ounces of blood to die, then it needs to lose 29,600 drops of blood! That would be a long blood trail if only droplet-size sign is found!
To illustrate this another way, consider that a gallon of paint applied in a very thick coat covers about 400 square feet. The 74 ounces of blood loss required for a 200-pound buck to die is 58 percent of a gallon. So, if all 74 ounces of blood were left as sign, there would be 232 square feet of blood on the ground and/or vegetation.
Whew! That means if a deer left a solid blood trail two inches wide and the equivalent of a thick coat of paint, the trail would stretch for 1,392 feet, or more than a quarter mile in length!
Even if our illustration is a bit off, the point is clear: a deer has to lose a lot of blood to die and will leave a lot of sign unless the blood pools internally. Knowing this certainly makes it easier to understand why some deer are able to travel considerable distances even after being mortally wounded.
Sharp Is Deadly
The best way to ensure that a deer shot with an arrow leaves plenty of blood on the ground (rather than pooling inside the body cavity) is to create a low exit wound. It is also very important that hunters employ razor-sharp broadheads at the end of their arrows.
This is where the "paper cut" from the title of this article is relevant. Have you ever noticed that if you get a cut from trauma, such as mashing your thumb with a hammer, there usually isn't much blood loss but if you get a small paper cut it seems to take forever to stop bleeding? The reason cuts that result from blunt trauma don't bleed as much as wounds from sharp cuts is because the trauma stimulates the release of Thromboplastin. This is a plasma protein that rapidly aids in blood coagulation.
A dull broadhead will cause trauma and stimulate the release of more Thromboplastin compared a broadhead that is razor sharp. Both a dull and razor-sharp broadhead may kill a deer if it passes through vitals or major blood vessels. However, there will typically be more blood loss in a shorter period of time if the broadhead is razor sharp. This reduces the deer's survival time and the distance it can travel before expiring. Shorter blood trails make for much easier recoveries!
BOWHUNTING has published several broadhead tests over the years, including a test of the most popular mechanical styles in this year's September issue. These tests include data on the sharpness of broadhead blades, and this data provides very meaningful information to bowhunters! In case you missed it, the five sharpest heads in this year's test were the G5 Havoc, Wac'Em 2-Blade EXP, Innerloc Shape Shifter, Muzzy Trocar HB and Rage Hypodermic +P.
Even after purchasing an extremely sharp broadhead, however, there are still several things to consider regarding how those heads are handled and used prior to heading afield. I prefer to keep broadheads in the factory packaging until I'm ready to test and use them. To test, I weigh each broadhead to ensure there's almost no variation among the broadheads and the practice heads I've been using. I then spin test each broadhead on the actual arrow shafts I'll use to hunt.
Finally, I make sure these arrows are stored in a container or quiver that protects the sharpness of the blades. I prefer quivers that grip the arrow shafts in two locations to hold them solidly and quietly with a hood that protects the broadhead without touching the blades. These steps — and making a good shot — almost always result in a short blood trail, an easy recovery and fresh venison.