If you hunt, you probably know where to aim on a big-game animal for a fast, effective kill. But have you ever thought about what’s actually happening when the animal is struck with your bullet? There are, essentially, three different ways to kill an animal with a projectile.
First, understand what happens when a bullet strikes an animal’s flesh. A bullet flying through the air carries a lot of energy, and when it hits a target, it begins to transfer that energy into the animal—tearing and crushing the soft tissue. You know what that looks like because it leaves a literal hole you can follow. Energy transfer also happens in the form of hydrostatic shock: Essentially, a bullet striking soft tissue (which has a high percentage of water/fluid) creates a pressure wave or shock wave that travels through the tissue, causing damage along the way. This is, in very simplified terms, why you can look at a bullet’s path through ballistics gel and notice that the wound channel is considerably wider than the diameter of the bullet. That damage is the temporary cavity caused by the shock wave.
Now, where and what that energy transfer impacts and destroys will determine if and how the animal expires. There are basically three bodily systems we can incapacitate to kill a big-game animal efficiently. Shut down one of these systems and it’s lights-out: The circulatory system, the respiratory system or the central nervous system.
The Circulatory System: Hemorrhaging
The circulatory system circulates blood, and it includes the heart, arteries and veins. Any bullet impact is going to destroy some veins and probably some arteries, and as the animal bleeds (internally and/or externally), blood pressure drops and oxygen can’t get to the vital organs. When blood pressure drops low enough, the animal “bleeds out” and dies.
A shot to the heart is a fast way to shut down the circulatory system. An animal hit in an area that lacks a lot of major arteries, say, the haunches, will probably not bleed enough to shut down the circulatory system, or at least not very quickly. That animal will either bleed out so slowly that the hunter might not find it, or it could survive the wound.
The Respiratory System: Suffocating
The respiratory system is responsible for breathing in oxygen and breathing out carbon dioxide. If a bullet impacts the lungs or diaphragm, air can’t move in and out of the lungs the way it should, and oxygen can’t get into the system. An animal shot in the lungs will quickly suffocate.
Suffocation or shutting down the respiratory system will also involve some level of hemorrhaging, as the animal can bleed into its lungs, preventing the absorption of oxygen.
The Central Nervous System: Powering Down
The central nervous system controls the whole body, carrying signals from the brain to control all the other systems. Generally, a direct shot to the CNS causes an instant incapacitation, as it essentially powers down all the systems at once.
The brain and the spine are the two main components of the central nervous system, and an animal hit in either of these two places will typically drop where it stands. Brain-shot animals will generally be dead before they hit the ground. Spine-shot animals might not die immediately but will be unable to get up and walk; they might need a follow-up shot, particularly if you are bowhunting.
What This Means for Aiming
So, three ways to kill an animal effectively. What’s the best one?
Well, there’s a reason we teach hunters to aim for “the boiler room”—the heart/lung area. This is a relatively large aiming point, with a generous margin of error. On a white-tailed deer, it’s about the size of a pie plate. If you hit the relatively small heart, great, you shut down the circulatory system and get a pretty quick bleed-out. If you hit the relatively large lungs, great, you shut down the respiratory system with a side of hemorrhaging, and the animal suffocates in seconds. Any halfway decent shooter can hit this big aiming point, particularly if the animal is standing broadside.
However, as mentioned, short-circuiting the central nervous system is a nearly guaranteed instant lights-out—so why don’t we just do that?
The answer is that the spine and the brain are both pretty small targets, and the margin of error is razor-thin. A deer’s brain is about the size of your fist, and it’s protected by the skull. On top of that, the head and neck are in near constant motion even when the rest of the animal is still. If you miss that tiny moving target by a couple of inches, you will either have a clean miss (phew) or you’ll shoot half the deer’s face or jaw off and it will slowly starve to death. I promise you, this is a horrible sight and a cruel fate. Don’t take the risk.
The spine is also a very small target, and depending on how much hair and fat the deer has, it might not be exactly where you think it is. If you miss, you’ll either have a clean miss over the back or a high-in-the-body wound that doesn’t bleed very much, leading to a difficult tracking job at best and a lost, wounded animal at worst. Even if you manage to hit the spinal column but fail to sever the spinal cord (a very thin, invisible target), you could very well be required to shoot again, which we always want to avoid if possible. Efficient, one-shot, quick kills are our goal. Don’t take a spine shot.
Some hunters like to shoot deer in the neck, arguing that it ruins very little meat. This might be true, but they are counting on hitting either the spinal column (to shut down the CNS) or a major artery (to shut down the circulatory system) for a kill. Trouble is, both of those targets are pretty invisible and frequently in motion, like the head. There’s a whole lot of real estate in the neck that will miss both of those systems but could damage the esophagus or cause slower bleeding, neither of which is the efficient, humane harvest that we’re looking for.
Bottom line: While there are three bodily systems you can shut down to kill a big-game animal quickly, by far the most reliable aiming spot with the highest chance of success is the large “vital zone” that contains the heart and lungs. A good shot here will damage the circulatory and/or respiratory systems and result in the most ethical, efficient kill possible.
