Just for conversation sake I will mention that I have a block of 3” foam covering the window and two small holes cut out to push the rifle barrel / forearm and scope through. The foam seals up around the forearm and scope so that no light from inside the cabin can be detected on the outside, so the window isn’t totally open so that sound easily goes out. I am not saying that coyotes can’t hear the click of the illuminator since I don’t know for sure, but I will mention that I have used that illuminator on other coyotes that paid no attention at all when I turned it on. If they heard the click you would think they would immediately look toward the cabin.
Coyotes look toward the cabin often and abruptly whether I deploy the 850 illuminator or not. One daytime coyote quickly looked toward the cabin more than once, with no movement from me nor click of the IR.
Coyotes definitely see the red glow of the emitter, no question in my mind, based on the many different ones I have observed there, but they have different responses to it, such as Tripod in the above video. At the click she didn’t look immediately but then did a couple of seconds later. She wanted to stay at the bait site but glanced at the IR again and instantly turned to leave. The coyote the other night looked abruptly when I clicked the IR and I can see how it’s possible he heard the click, but also he saw the red glow and that’s what caused him to leave suddenly, in my opinion.