Originally Posted By: SkyPupBTW, No terrestrial mammal of any species has ever had any response to IR in my career in Veterinary and Human Opthalmology, including no mouse, no rat, no rabbit, no guinea pig, no ferret, no chicken, no mongoose, no feline, no canine, no porcine, no bovine, no water buffalo, no mountain lion, no equine, and no homo sapien has ever had any pupillary response to any non-visible electromagnetic radiation of any kind, including all wavelengths of IR. Their pupils did, however, all respond to visible light.
To help substantiate many of the empirical claims made in this thread, I did hear of a woman in the University Eye Clinic once who claimed that MHz cell phone signals from cell phone towers and her cell phone caused pain in her eyes though, but she was in a psychotic state and had to be examined in a straight jacket and was taken away by armed men.
I am sure you have witnessed a threshold visual field test performed on a human given your background. You can not see a pupil response when even the brightest stimulus is used when a Humphrey or similar unit is used, yet the person obviously sees the light. My point is technology is not to the point where we can determine what an animal can truly perceive. Do I believe a coyote can see IR? No. Do I believe they can see the emitter? Yes. If we were to use a red and green filter over the emitter to ensure NO visible light was being emitted then perhaps the critter wouldn’t see it. I would still only base my conclusions after experience in the field demonstrated this were true because again, technology is not to level where we can truly know what an animal can perceive.