I’m no expert on the subject but I experimented with both green and red lights for a couple of years before switching over to a persistent light. I had a driveway alarm set up in the yard that would alert me to activity, then I’d grab the rifle and quietly head outside and switch on the light to look for the visitor. The short answer is I saw no particular tendency for one color to be perceived as a more of a threat regardless of the type of critter.
Rats in particular are extremely wary and tend to high tail it at the slightest change in their environment, whether that be sight or sound. Since they are toward the bottom end of the food chain, I imagine that has been evolutionarily advantageous. But let me share some of my general observations and then we’ll get back to rats.
Possums and armadillos for the most part could not care less about what light shines upon them, seldom warranting even a casual glance in my direction. Several times I tried strobing possums and they paid me no mind.
Raccoons were more wary, usually giving a glance but half the time going right back to what they were doing. The other half of the time, they’d quickly move on. Never a panicked retreat that I can recall, but more of a “Hmm, I don’t like that. I’ll try this again later.”
The most wary were rats and red foxes. Every once in a while, they’d stay put when the light hit them but for the most part they’d retreat. A fox would typically bolt for the woods. Rats would generally retreat from the open and take cover in a pile of limbs and leaves where the edge of my property meets the wood line. From there they would tend to stare at the light. How convenient…two nice glowing dots to aim at. It was a rare treat to see a rat, probably not so much because they are scarce but because they aren’t as likely to set off the motion sensor. But yeah those glowing eyes make for useful aim points at 40 – 50 yards against an otherwise washed out background.
Something else to consider…we see green light more easily than red so all else being equal, you’ll have better visibility with green light. But at the same time, red light better preserves our night-adapted vision. Either one will do just as well at lighting up some eyes at distances out to 75 – 100 yards. If memory serves, guys who do a lot of ratting say red is better so if that’s what you’re going after, that may be a good reason to choose red. But for example if you have some armadillos tearing up your yard at night, they’re not going to stop and look at you with glowing eyes so a green light will let you see them better and still be useful for the other critters who do.
With all that being said, a better approach is to avoid using an on-demand light and instead set up a soft permanent light so the rats will get acclimated to it. Then put some sticky bait out…something they can’t grab and go. Peanut butter is a common favorite. They’ll be dying to get to it.
