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User Icon     Posted 10 months ago     by Jim Hook     

Is the use of Thermal Imaging for deer stalking ethical?

It probably wasn’t that long ago that the same question was posed against the modern telescopic sight, but all new forms of technology have the potential to instigate debate often fuelled by passionate beliefs of right and wrong. Thermal imaging (TI) technology isn’t new. First discovered in 1800, it's been used by the defence sector for a number of years but it has improved beyond recognition from the bulky, power hungry, low resolution versions that even the military were using until the late twentieth century. The commercial market started slowly enough to provide solutions for medical and industrial requirements. Hunting was a late adopter but the market, and the providers, have grown quickly. Choices are now varied with hand held spotting scopes, binocular variants, and rifle sights that are indistinguishable from standard telescopic sights to look at, readily available. Manufactures include Pulsar, Flir, Zeiss and Hik Vision to name but a few. Prices vary from as low as £400 to as much as £6000 but the old adage ‘you get what you pay for’ is very applicable to this technology field.

Technically, all of the TI products marketed for hunting operate within the Long Wave Infrared part of the electromagnetic spectrum. The reason for this is that devices operating in the LWIR spectrum do not need to be ‘cooled’ to work effectively. Cooling draws current, and thus uses more power than uncooled systems. Furthermore, cooled systems are more sensitive and can be used for longer range observation than uncooled devices. As a result, uncooled devices can provide the detection range required for hunting, last longer on batteries, and cost significantly less than cooled sensors. They are also smaller! This means they adhere to the consumer size, weight and power (SWAP) model, as well as being ‘affordable’.

Thermal imagers work in day as well as night conditions. All a sensor needs to produce an effective image is a good temperature coefficient. If, as on a warm day, all objects within the sensor’s field of view (FoV) are radiating at a similar temperature, due to heating from the environment, then the image displayed to the user will be poor as no one object will stand out from any other. On a cold day however, warm blooded animals have a greater difference of temperature to the background scene and as a result stand out far clearer in a rendered image. These conditions occur more often at night and winter as opposed to daytime and summer.

Using TI for hunting offers great advantage over not using it. Effectively the limitations of our own sight are overcome as the sensor can quickly pull out a deer from the background scene where it is located. To some this may be seen as an unfair advantage but to others its simply a case of levelling the playing field a little as the deer’s eyesight, hearing, smell and general alertness are significantly better than ours. That said, I’ve stalked with people who can spot an antler protruding from behind a tree stump with their ‘mark 1 eyeball' from a significant distance, where the TI scope couldn’t even detect a heat source due to the shielding provided by the stump. We aren’t all born equal however. I know I’ll never be as ‘fortunate’ as George Clooney, I’ll never be as fast as Usain Bolt, and I’m unlikely to ever be as good a hunter as Steven Rinella. Thats not down to commitment and determination. It is simply down to the fact that we aren’t all equal in physical prowess, mental ability or natural skill in different activities. At the same time, for me, using TI (yes I do use it) isn’t designed to give me an advantage over my prey and make it ‘easy’ for me to achieve a successful hunt. Indeed, detecting a deer using thermal and then shooting it wouldn’t be hunting to me. I like the challenge of getting close to my target. Equally, I’m not really that worried about how far from civilisation I am when I kill an animal as the extraction is part of the experience. Don’t get me wrong, if I see a big red stag and I’m 2 miles from a road I’m definitely going to think about my options for recovering the carcass and I may well decide not to shoot the beast, but that will be more down to time and light rather than simply an aversion to carrying it out.

Its important I differentiate here the difference between using TI for deer stalking and using to for deer management. Whilst the permission I have for deer stalking is actually as a result of the need for the forestry commission to manage deer, I mentally separate the two. On most of my outings I am deer stalking. On others, generally later in the season, I will definitely be deer managing where numbers are needed to meet the management plan quotas. On these excursions, success trumps my own need for the challenge but I go out with a different mind set and accept the difference easily. Why do I want to differentiate these two types of outing with regard the use of TI? Well, when I’m stalking I use TI to spot deer across large open expanses bordering up to forestry edges. These openings can be 500-1000m across so detecting a deer is only the start of the stalk. My permission spans some 20,000 acres so knowing there are deer active in the block I intend to head for is important in helping support success. I don’t use TI to shoot a deer. In England and Wales it is legal to use a thermal rifle sight to shoot deer during the day but for me the only role my TI sight has is for managing foxes and it lives permanently on my .222. In Scotland it's illegal during both day and night. For deer stalking I use a handheld spotting scope only. Once I’ve detected the deer I switch to using glass, supplemented by thermal, and shoot using a standard glass telescopic sight. For those people professionally engaged in deer management I can fully understand if they decide to use TI rifle scopes to shoot deer as it provides a clean, efficient and effective tool for, what can be, a time sensitive task.

Ethics are, to a degree, a personal measure or right and wrong. One person’s right will be another person’s wrong. In this area of activity I believe it’s the individual's decision that is important. A more general community determination of right from wrong doesn’t always get it right as all of us engaged in countryside pursuits can understand! I do think however, its comes down to your own appetite for ‘fairness’. If you think it’s fair for you, based on your own evaluation of your skill and motivation, then thats all that matters as long as you are complying with the law. For my own judgement of fairness I prefer to limit my TI use as described earlier but I also look forward to being able to use it less and test and develop my own existing ability further.

If you are interested in buying a thermal device then Scott Country ( are one of the biggest suppliers but you can also get it, like most things, on Amazon!

We've recently become an Amazon Affiliate to help link you directly to products we think are good, whilst generating some revenue to help fund our website, films and podcasts:

Pulsar Axion Key XM30 Thermal Imaging Monocular -

Pulsar Thermion XM50 5.5-22x42 Thermal Riflescope -

Pulsar Trail LRF XP50 Weaver 76519 Thermal Visor -

Flir 431-0019-21-00S Wildlife Scout II 640 Camera -

Zeiss ZEISS DTI 3/35 Thermal Vision Monocular -

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