Sunday, April 22, 2007

Does my camera drive bats batty?

My intended destination, Sawbo Marsh, was closed (and will be so for a few more weeks), so I went a few miles north to Tednambury Marsh. Diligent work by local watchers has produced a good number of Grasshopper Warblers in the Stort Valley recently, and there were a couple reeling away thie evening. I have this problem with Groppers that I hear snatches, and then there’s always a wren singing too, so was it just that churry bit of the wren’s song? But I finally got enough of a song on one, and the other was whirring away like it was powered by Duracell.

As we (self + D#1) left we walked up the lane from Gaston Green marina to the pond at the top of the road in the gloom (8:30 ish). The road is lined with bushes, and bats were whizzing up and down often just a few feet from our head. We stopped and watched for a while. My bat ID expertise is similar to my plants/butterflies/anything else, but I got the impression these were both bigger then Pipistrelles and not flying the same way, but smaller than Noctules.

Anyway, I tried to take a photo with the flash, and failed miserably. Then I got to thinking; my lenses are “ultrasonic” lenses. So presumably they auto-focus by using ultrasonic beams to find distance in the same way bats do. And the logical thing to do would be to use the same frequencies – why try to improve on nature?

So when I was trying to take the photos were the bats suddenly getting a blast of ultrasound? Was it like my camera screamingly loudly at them?

Here’s some atmosphere whilst I’m pondering this

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