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Native Californian, biologist, wildlife conservation consultant, retired Smithsonian scientist, father of two daughters, grandfather of four. INTJ. Believes nature is infinitely more interesting than shopping malls. Born 100 years too late.

Sunday, February 18, 2007

The end of the experiment (for now)

To bring you up to speed -- in the two previous wood rat blogs I recounted several of my embarrassing experiments on the climbing ability of a local wood rat. Because I had misinterpreted the photos and made incorrect assumptions, I was blissfully pursuing an experimental path of self-deception. Then I realized I had underestimated the rodent's gymnastic skills. To wit, it had been shimmying up a 3/4" pipe and negotiating the overhang of the bait station. So I used a "squirrel baffle" to prevent the trickster from reaching the bait station by the "impossible route". That experiment demonstrated to my own satisfaction that the rodent had shimmied up the 3/4" post rather than climb down the 2" PVC pipe, as I had been mislead to believe. That's where we left off.

I still harbored a belief that the wood rat could "chimney stem" down the inside of the PVC pipe. As mentioned, he had never descended the pipe, either inside or out, to reach the bait station. But I thought he could do it. He might need to build confidence using the tube horizontally before trying to go down it vertically. With the squirrel baffle on the post, the gently inclined PVC pipe was the easiest route to the bait station. (I didn’t think he was desperate enough to try jumping the 28-inch span). I hoped of course to get that one shot of the rat entering or exiting the pipe.

It rained that night, and when I checked the camera the next morning, two pictures showed the rat stepping off the pipe. It seemed to use the PVC as it would a branch.

Another picture however looked like the rat was peering into the tube.

I looked inside the tube. It was still coated with dust. If the rat had passed through, it would have been swabbed clean.

So I fastened the tube to the overhead branch -- the vertical access route. I was leary he might shimmy down the outside of the tube, so I jury-rigged a baffle from a plastic milk container. There was another potential flaw in the set-up. In an attempt to surmount the milk container he might drop to the top of the squirrel baffle below. From there he could climb up to the bait station. To prevent that scenario I suspended the bait station at the end of the tube, and removed the vertical post.

The peanut butter was untouched the next morning. The baffle had worked. I turned off the camera thinking the experiment was over. But when I came to collect the camera the next day the peanut butter was gone! Wonder rat had circumvented the baffle on the second night, and there were no documenting pictures. The inside of the tube was still dusty. If only I had a camera trap that shot video!

I consulted with neighbor Richard, who advised me to replace my shabby plastic baffle with a two-pound coffee can.

The new baffle did the trick. The next morning the peanut butter was untouched. I had enough. The question of chimney-stemming would have to remain unanswered until some later date. I just can’t believe that this wood rat can’t pass through a 2-inch pipe, but for some reason he wouldn’t have any part of it.

Reflecting on all of this I thought about the advantages of a camera trap that uses video.

That night I was sitting at the kitchen counter as my wife was cooking dinner,

"You know, sweetie, if I had a video-camera trap I could get some fantastic footage. It would be pretty neat seeing that rat in action, wouldn’t it?"

"Yeah, that would be nice", she admitted. "But it would be nice to see the leaking roof get fixed too."

Obviously she wasn't buying it. I guess my timing was off.

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