A comparison of kill zones and their compliance with the Australian humaneness model
By Bob Gough
All hunters want to harvest game humanely and strive for a quick and clean ‘one shot’ kill – it’s what ethical hunting is about. Most of us develop our marksmanship skills through regular practice at the shooting range, and we know our ‘ethical range’, that is, the range at which we can humanely take a deer. Shooting a deer is a complex task that requires significant concentration, and in the field there are many variables. The variability and complexity of the task naturally lead us to select the chest or heart/lung kill zone because it has the greatest margin of error.
Hunters, veterinarians and scientists know that the heart/lung shot is humane. This is recognised in ‘best practice’ and scientific literature such as: Sharp, T. and Saunders, G. (2011). A model for assessing the relative humaness of pest (sic) animal control methods (Second edition). Australian Government Department of Agriculture, Fisheries and Forestry, Canberra, ACT. (Sharp and Saunders Model).
The Sharp and Saunders Model assessed a range of wildlife control methods using an expert panel comprising of members from the Centre for Invasive Animals Solutions, the Chief Scientist of RSPCA Australia, the NSW Vertebrate Pest Research Unit, and Veterinarians from the University of Melbourne and CSIRO to validate a range of best practice control methods that are known as the Pest Smart Standard Operating Procedures (SOP). These SOP are published by the Centre for Invasive Animals Solutions https://invasives.com.au/; and deer hunters will be most interested in(SOP) DEE001 Ground shooting of feral (sic) deer.
The aim of The Sharp and Saunders Model is ‘to produce a practical, general model of humaneness assessment that can be applied to any control method’. The model states that the ranking process is an enabler not an inhibitor; that it provides support to control techniques through evidence based objective assessment.
Appendix 12 of the Sharp and Saunders Model presents a series of humaneness assessment worksheets and matrices for 12 different animal species commonly found in Australia. For deer, this reference lists ground shooting using head shots as most humane, followed by ground shooting using chest shots then aerial shooting using chest shots.
Appendix 1 of the Sharp and Saunders Model refers to an unnamed study that examined the effects of wound site and blood collection methods on biochemical measures obtained from red deer and found that in a cull sample of 69 red deer that 84 per cent of 69 animals were killed with a single shot and no deer escaped wounded. Eleven of the deer were shot twice (and one deer was shot three times), the first shot usually being in the chest. Of the deer killed with one shot, 38 per cent of stags and 80 per cent of hinds were shot in the head or neck. When deer had been shot in the chest, they often ran a short distance. An estimate was made of the time between the first shot and the deer falling to the ground. The median time was 60 seconds for the multiple shot animals and 0 seconds for the single-shot.
The Sharp and Saunders Model also discusses ‘hydrostatic shock’, where, in addition to the damage caused by the penetrating projectile, there is scientific evidence that organs can also be damaged by the pressure wave that occurs when a projectile enters a viscous medium. Brain damage may also occur when the pressure wave reaches the brain from the chest cavity via major blood vessels (this is well noted in presentations on the subject by ADA stalwart Dr Matt Draisma, veterinarian and deer hunter). It is also thought that hydrostatic shock may produce incapacitation more quickly than blood loss effects, however not all bullet impacts will produce a pressure wave strong enough to cause this rapid incapacitation. This is the reason for minimum calibre requirements for deer species afforded by game status (by comparison, there is no minimum caliber required for goats or pigs when managed as pests).
SO WHY DO HUNTERS PREFER THE CHEST KILL ZONE?
The answer depends on who you ask. People who know nothing of hunting and who don’t support hunting may answer that hunter’s prefer chest shots because they want to keep the antlers. Whereas the truth is that hunters prefer chest shots for the following reasons.
Size of Kill ZoneThe brain of a deer is approximately 80 millimetres in size and is encased in the bone of the skull. The heart/lungs of a fallow deer are around 250 millimetres, and obviously larger for sambar, rusa and red deer. The heart and lungs are protected by the ribs and the bones of the shoulder. It should be noted that deer frequently stand without body movement and move their head to scent and see. This behaviour increases the complexity of brain shots.
Comparison of Effect (Assuming that hydrostatic shock is present in both brain and chest shots.) The brain shot targets the central nervous system (CNS), while the chest shot targets the CNS, respiratory, locomotive and circulatory systems, therefore; a chest shot offers damage or destruction to four essential life systems with over double the room for error over a brain shot that only targets one essential life system. Clearly the chest shot is the lowest risk shot. For example, when ground shooting on foot in field conditions, the hunter may have an increased heart rate from exertion in steep country; or the firing position may be less than ideal; or the distance to the target may be misjudged due to terrain or light effects where animals may appear closer across a deep gully (the ‘dead ground’ effect). Add to this the variability of the wind in steep terrain and an error of 50 millimetres at 100 metres is quite possible.
Given the conditions above, a shot directed at the brain could miss the brain and damage the animal’s jaw. In this scenario, the animal will initially drop at the shot, then, depending on any damage to the nervous system, the ‘adrenalized’ animal will get up and run some distance because there is no damage to the locomotive system and minimal damage to the respiratory and circulatory system (blood loss will not be significant).
By comparison, the same 50-millimetre error in a shot directed to the chest will probably still strike the heart. It will certainly strike the lungs and the bony structures of the shoulder and ribs. Fragments of the bullet and bone from the shoulder and ribs will create secondary projectiles that will increase wound effects. Penetration of the chest by the bullet and bone fragments will create a tension pneumothoraxand further reduce the animal’s ability to breathe. With significant damage to the nervous system, respiratory, locomotive and circulatory systems the animal will have difficulty rising and time to insensibility and death will be short.
Animal welfare groups and other uninformed commentators who decry the preference for chest shots by ground shooting recreational and volunteer program hunters should broaden their knowledge and read the Sharp and Saunders Model and various Pest Smart SOP that allow for both brain and chest shots for ground shooting. The Sharp and Saunders Model rates chest shots only second to brain shots in humaneness.
In conclusion, shooting a deer is a complex task that requires a range of skills and significant concentration. All hunters strive to take game humanely, we know our ‘ethical range’ and we prefer the chest or heart/lung kill zone because it damages four essential life systems with over double the room for error over a brain shot that only targets one essential life system. The purpose of this article is to inform hunters that the humaneness of the chest shot is recognised in ‘best practice’ and scientific literature, and so hunters can refer to The Humaneness Model and SOP DEE001 in any discussion on the humaneness of hunting.
Above: The Sharp and Saunders scoring matrix for overall welfare impact
Above: The Sharp and Saunders matrix of relative humanness of wild deer control methods