Mouse Cam

A few years ago, Bart Locanthi pointed out that CCD cameras were sensitive to the near infrared spectrum, but most have a filter to block that range out. (Try shooting your TV remote control at a camcorder.)

One company took advantage of this, selling a cheap monochrome video camera with internal near-IR LEDs for illumination. We had mice in our house, so we set up this camera in the games closet, shown at the right. We plugged it into a VCR and started recording on 8-hour tapes.

We caught our first mouse within a few minutes. (He was probably the one who had made litter out of the contents of a juggling ball, which had caught our attention in the first place.) We caught six more, including a couple of vole or shrew-like creatures. Recent tests indicate that the house is mouse-free, or at least free of the kind that fall for our peanut butter.

Here's a four-minute MPEG (30 FPS, 30MB) of one volunteer.

The movie had three segments of 27, 48, and 46 seconds of excessively cautious (i.e. off-screen) mouse elided. Other volunteers tended to be bolder. It took more CPU cycles than I used in my entire geeky undergraduate career to convert the movie from SGI movie to MPEG format.


What do we do with the mice? Most are sentenced to exile in a baseball field near the quarry on the other end of town. The most recent was released at the wooded end of an AT&T parking lot nearby. There are a lot of hawks around here. It would be entertaining to enclose one and see one of these hawks do its stuff. Or donate the live rodent to the Raptor Trust.

Why do the eyes glow? It's mouse infrared-eye, the rodent equivalent of redeye in a snapshot.

Can the mice see in the near infrared? Despite the nervousness of the mouse in the movie, we've seen no evidence that the mouse can see near-infrared. Knowledgable contradition or experimental design is welcome.

Is the Have-A-Heart trap more humane than a traditional bone crusher? Not if you forget to check the trap. One shrew-like creature overheated and died before we noticed him. They need water frequently, and the peanut butter bait doesn't help.

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