The Mouse Test

Since many of my camera trapping projects are focused on small mammals (pun intended), whenever I build a new hack, one of the first tests I put it through is the "Mouse Test."

I.e., if I set it 24 inches away from a rodent burrow, about 12-14 inches off the ground, and sprinkle a handful of seeds at sundown, how does it perform?

Is it sensitive enough to reasonably capture the ensuing "clean up" without running frantically all night, triggering at every small twitch? Or, is it not sensitive enough and missing the activity?

How are the exposure and flash? Is it blowing out the scene because of the short distance?

What about sharpness, focal depth and color/white balance?

Below are the recent results of just such a test. The new cam trap combines a Sony Cyber-shot DSC-W220 point-and-shoot digital camera with a SnapShot Sniper controller card.

The Sony W220 is 12 mega pixels, has a nice, wide 28mm lens, auto-focuses down to 1.2 inches, and has an adjustable flash and programmable settings, such as exposure value (EV), ISO, and white balance. All highly valuable features for small mammal photography.

The SnapShot Sniper is a versatile cam trap controller card that also has a good range of programmable settings, including a sensitivity adjustment for the embedded motion sensor.

And the combo seems to be working well. During the Mouse Test it captured 96 photos in a bit over 5 hours (~ 9pm to 2am), with no obvious false triggers.

So now let's look at the pics.

3 different deer mice worked the scene - one brown, one rufous, and one gray with more white on its sides. Tail, ear, body and foot proportions suggest all are Peromyscus maniculatus.


Deer mouse #1 to the scene, including ground beetle entourage


Deer mouse #2 - more rufous


Deer mouse #3 - grayer with much more belly white up the sides

Another "mouse" also joined the foraging fun - a Great Basin Pocketmouse, Perognathus parvus. It's a Great Basin species that barely ranges into California.


Great Basin Pocketmouse, a mouse-size relative of the kangaroo rats





A kangaroo rat, the much larger relative of the pocketmouse, also worked the seed scene. In this case I think it's Ord's Kangaroo Rat, Dipodomys ordii. It seems to be the standard species on the sandy sage steppe flats in the Mono area.

Note - for size comparisons, the above 6 and following 2 photos are all the same crop.


A kangaroo rat, likely Ord's k-rat - as sweet as any gerbil or hamster


Now that's a tail built for balance!

And finally, here are 3 detail crops of the above.

Detail crop of deer mouse

Detail crop of pocketmouse

Detail crop of much larger kangaroo rat

Not bad at all. A bit overexposed when within 12 inches, but I should be able to handle that by dropping the exposure value by -1/3 or -2/3. Fixing the ISO to 80 or 100 might help, too.

I'd say it passes the Mouse Test. What do you all think?

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References:

• Nature of a Man (this blog) - Deer vs. Kangaroo
• Nature of a Man (this blog) - Becoming Size Wise
• E. W. Jameson, Jr., and Hans J. Peeters, UCPress - Mammals of California
• Snapshot Sniper - controller cards and DIY supplies for making camera traps
• Sony Cyber-shot DSC-W220 Digital Camera

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