Ruminants and colour perception

widu13

Well-Known Member
I watched some telly last week and this was mentioned- I've forgotten the name of the programme. The current scientific thinking is that we see in "tri colour" and ruminants see in "bi colour". They showed an example of what bi colour is and it is colour but not quite as vivid. It certainly is not black and white nor anywhere near it. I always thought the B&W bit was nonsense!
 
Just found this on the interweb

"The Study
In August 1992, a group of leading deer researchers and vision scientists gathered at The University of Georgia (UGA) in Athens to conduct this landmark study. The group of researchers included Drs. R. Larry Marchinton and Karl V. Miller, and myself from UGA, Dr. Gerald H. Jacobs and Jess Degan from the University of California, and Dr. Jay Neitz from the Medical College of Wisconsin. This study was made possible due to a highly sophisticated computer system developed by Dr. Jacobs. This system is based on the principle that an electrical response is produced when light enters the eye. The computer interprets these responses and translates them into a “scientific best guess” of what deer can actually see.

Findings of the Study
The results of our study confirmed that deer possess two (rather than three as in humans) types of cones allowing limited color vision (Figure 1). The cone that deer lack is the “red” cone, or the one sensitive to long wavelength colors such as red and orange. This suggests that wearing bright colors while hunting does not affect hunting success. This does not mean that these colors are invisible to deer, but rather that they are perceived differently.

Deer are essentially red-green color blind like some humans. Their color vision is limited to the short (blue) and middle (green) wavelength colors. As a result, deer likely can distinguish blue from red, but not green from red, or orange from red. Therefore, it appears that hunters would be equally suited wearing green, red, or orange clothing but perhaps slightly disadvantaged wearing blue.

The results regarding the UV capabilities of deer were equally fascinating. Our results confirmed that deer lack a UV filter in their eye and that their vision in the shorter wavelengths was much better than ours. Deer also were found to have a relatively high sensitivity (good vision) in the short wavelengths where UV brighteners and dyes are active.
While not entirely conclusive, this finding suggests that deer are capable of seeing some UV light and that fabrics containing UV dyes and brighteners may be more visible to deer than to humans."
http://www.northcountrywhitetails.com/articles/whatdodeersee.htm

Very interesting, i'd always subscribed to the monochrome idea for animals such as deer until just now.

Cheers
Hyperion
 
The show gave an example of the colours that would be seen. If you imagine a lightly faded colour photo it was like that. All the colours were there, just faded/not as vivid. This is the latest thinking, not the '92 research.

It was a countryfile type program which featured it, but it was mid week.
 
Hmmmmm trying to do a bit more digging, seems strange though that animals should see all the colours yet in a more subdued way, surely if they see in colour they would see all of them in a similar way to us?
 
From what I can find with out going to deep into it and the most upto date thing I can find is 2003, deer are "Dichromats" having only two cone type receptors and see colours in the blue to yellow green but can also discriminate longer wavelength light (reds) from blues and greens, so yes they do see all the colours but in a more subdued way but see further into the blue end of the spectrum than us.

http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1279&context=icwdm_usdanwrc

Cheers
Hyperion
 
I don't believe any of the 'can't see red wavelengths' stuff. As an illustration of this, I often watch red deer when I'm out foxing using either my thermal or my NV. So long as the wind direction is right, I can do so for as long as I want. The moment I turn the IR laser (~850nm) on, however, they usually jump up in alarm and bugger off.
 
I don't believe any of the 'can't see red wavelengths' stuff. As an illustration of this, I often watch red deer when I'm out foxing using either my thermal or my NV. So long as the wind direction is right, I can do so for as long as I want. The moment I turn the IR laser (~850nm) on, however, they usually jump up in alarm and bugger off.

I've noticed the same thing with IR iluminators when shooting rats with the night vision Paddy
 
I have posted some further photos in the DPM v MTP thread in Equipment and Accessories. These I have processed to give approximately what I think people are trying to describe in terms of deer colour vision.

What is interesting is that when I virtually dump all the red channel colour information I think that contrast and the ability to make out shapes in the shadows improves. None of the cammo patterns works very well in the "supposed deer vision" processed photos.
 
Those pictures certainly show the contrast between the back grounds and the cammo Caorach, but both types blend in well given different back grounds, would be interesting to see the same experiment conducted with say a deer skin and some drab brown clothing
 
Lots of hunters have always said deer couldn't see colours but with an animal that inteligent and with the eye's they have i think they can see colours.
 
Those pictures certainly show the contrast between the back grounds and the cammo Caorach, but both types blend in well given different back grounds, would be interesting to see the same experiment conducted with say a deer skin and some drab brown clothing

I don't have a deer skin to hand but if I get the chance then I might continue the experiment and expand the range of clothing I use as the results might be interesting. I must highlight that I'm just messing about and there isn't much hard science behind what I'm doing as I lack the knowledge to understand deer vision even if someone was to tell me exactly how it operates.
 
With the night vision at 850, Is that long or short wave. And isn't it more IR than red?

850nm is a longer wavelength than visible light, but it must be remembered that although an IR illuminator is rated at a given nm value, that isn't an absolute. It will also put out a degree of light either side of the given figure, and so a certain amount of visible red can be seen - both by humans and deer.
 
More tests and lots of photos for other patterns in a range of settings in the equipment and accessories forum. Enjoy...
 
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