Thursday, December 26, 2013

Deer Reactions to Flash

For some time there has been a discussion among those who run camera traps about how wildlife, especially white-tailed deer, react to the flash of trail cameras. In low light conditions – especially at night – a flash is necessary to obtain a photo. Some cameras use a “white flash” with which we are all familiar; others use an infra-red flash created by light emitting diodes that glow red for about a second; others use what is called a “black flash” that is actually infra-red but which cannot be seen by the human eye.
Some folks think that the glow of an infra-red flash is less startling to wildlife than a conventional white flash that seems to light up everything nearby. Others are of the opinion that a white flash resembles lightning with which most wildlife is familiar – and that wildlife doesn’t react to the very brief (typically 1/1000 second) white flash. 
While a case can be made for each side of this discussion, any of us who use both white flash and infra-red flash camera traps should be able to provide some empirical evidence of how wildlife reacts to a flash.
Herewith some examples. These two series of photos were both completed in less than one minute from the deer’s first appearance to when it disappeared from the camera’s view. A Sony P32 in a homebrewed camera trap using a white flash took the first five; the second four were taken by a Moultrie M80 camera that uses a visible infra-red flash. Although these were two different deer, neither of which may have reacted in the same way as other deer would – or as how these deer would each react on a different day or under different conditions – the difference in their responses is striking.

It’s rather obvious that the white flash resulted in a reaction that could best be called curiosity. On the other hand, the infra-red flash clearly startled the deer to the point where it fled. Over the time I’ve used camera traps to capture photos of wildlife, the cameras have gotten numerous series like this. Interestingly, while black bear, deer and raccoons often display curiosity and investigate the cameras; bobcats, coyotes, both species of fox, fishers, opossums, porcupines and rabbits seem to ignore the flash; white-tailed deer are the only species that appear to have been startled and then only by a visible infra-red flash.
So, for me the argument is settled and I now only use infra-red flash camera traps in areas where a white flash might reveal a camera’s location to other people.

No comments: