Friday, August 25, 2006

Alice Sees Red

Owls apparently have long memories for significant things like locations of predators. So it's going to take Alice a while to appreciate the fact that her two nemeses (the cats) have found a new and loving home far enough away they won't be coming back. It's only been two days, but she's still very arduously looking for them every time we go outside.

Anyway, two owl biologist friends of mine engaged in a discussion about whether owls can see red light. Some biologists use red filters on their lights on the assumption that owls can't see red light, but this hasn't been proven. Then there's the question of if they can see infrared light. How could they find out for sure? Ask Alice.

And so it came to be that Alice became a guinea pig to see if indeed owls can see red light.

This was kind of a fun one. I waited until after dark, when Alice was just sitting on the hall railing, not really looking out the windows or anything. I started with a laser pointer, since I know she gets very interested in following that red dot around on the wall and floor. And as expected, she got very interested in the red dot and watched it zip around on the walls, ceiling, and floor.

Then on to the flashlight with a red filter. (No problem to come up with since my husband has a thing for flashlights and has more than I care to count.) The light, of course, was not as focused as a tight little laser beam, and I had quite a bit of trouble getting her interested in it.

At first I didn't think she could see the light since she wasn't following it at all as I moved it around on the ceiling and walls. But with patience, Alice finally paid attention to that big red spot on the wall. She tracked it as I moved it up on the ceiling over her head to the point her head was almost upside down over her back. No room for doubt there...she would never do that kind of rubber-necking without a good reason. A second try got her to repeat the performance, so she was in fact tracking the red light.

Then I tried infrared. Thanks to a grant from the Wilson Ornithological Society and a nice discount from, I have a generation 2 night vision scope to use in my Great Horned Owl vocal study (so I can observe the behavioral context of the vocalizations.) I turned on the infrared (IR) illuminator and projected it on the wall to see if Alice would notice it. No amount of patience, movement, or anything could get Alice to notice it.

I also checked the response of Alice's pupils to the lights. They did contract slightly when a red-filtered light was shined in them. I couldn't tell on the infrared, since I was too close for the night vision to focus properly, and there was sharp contrast that my eyes couldn't deal with between illuminated and unilluminated areas. But I certainly wasn't going to shine a laser pointer in her eye!

So there you have it: crude and unscientific proof that Alice sees red.

Speaking of experiments on owls, I found a discussion thread about whether or not Great Horned Owls could hear the drumming of Ruffed Grouse. So I played one of my bird CDs on a computer hooked up to speakers with a subwoofer that can handle the low sounds well. She never let on in any way that she could hear it...but she also didn't seem to pay any attention to the higher pitched calls of the Ruffed Grouse played right after the drumming.

Attention span is definitely a factor in this sort of a thing.

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