Camera trapping bats accidentally and on purpose

Sonoma County bat and striped skunk meet at the water hole.

Photo by Sharon Ponsford.

It's a thrill to get a camera trap picture of a bat in flight, but it's usually accidental. 

Camera trappers usually don't set their cams in bat flyways, but when they do insectivorous bats trigger camera traps easily. 

Here's the rub. The bat is usually gone by the time the shutter is released.

Sometimes though an image is captured like the one above.

  

The likelihood of camera trapping bats is much greater when they are in a feeding frenzy over a mosquito-covered deer.  

The bat here was no doubt taking flying insects around the water, and the skunk was probably grubbing for insects in the mud.  

Rod Jackson and Sharon Ponsford set the camera, a Sony s600 with a YetiCam controller board at a water trough in Glen Ellen, California. 

Bat specialist William Rainy tentatively identified the bat as Lasiurus cinereus, the hoary bat, which happens to have a wingspan of 15-17 inches (second largest of North American bats).  

Rainy also put us onto some interesting references on the use of camera traps to survey bats. 

Hirofumi Hirakawa, a wildlife biologist from Sapporo, Japan, had often camera-trapped bats, but was frustrated with out-of-focus and poorly exposed images. 

So he designed a PIR-activated camera trap that uses a film camera and a pencil easer.

Yes, a pencil eraser. That's the bat lure. 

The eraser is attached to a piano wire in front of the PIR sensor.

The bats take their own pictures when they swoop in to check out the eraser. 

Some bats even bit the eraser in flight.

The methodology holds promise, but Hirakawa cautions that "we must be aware that different bat species might have different reactions to the luring device". 

Now, if the manufacturers ever make an inexpensive but really fast digital camera, I could be tempted to make some camera traps for bats.   

References

Hirakawa, H. 2005. Luring bats to the camera -- a new technique for bat surveys. Mammal Stusy, 30:69-71.

Hirakawa, H. and K. Maeda. 2006. A technique to estimate the approximate size of photographed bats.  Wildlife Society Bulletin 34:2, 413-418. 

[Many thanks for Rod Jackson and Sharon Ponsford for sharing the photo and their observations, and to Bill Rainey for his help.]