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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.

Tuesday, November 11, 2008

Camera Trapping 101- continued

I ran this post by Cliff Wheeler, a seasoned woodsman and one of the best camera trappers around, and I am happy to say that he shares my views. If you haven't been checking his blog, well, you've been missing a lot of great wildlife images and tips on camera trapping.

So getting back to the lecture, here’s how we see it.

Point 1) Despite our best efforts to hide them, our cameras don't go unnoticed.

  • Birds and mammals detect trail cameras by sight and scent.
  • Hiding a camera delays discovery and increases the chance of getting a candid picture. Cliff says, " disguising the camera with vegetation is much more effective than the camo on the camera case”. When he places a camera on a tree he covers it with moss, "but only for deer or coyotes, since most other animals seem to care less".
  • The sound of the extending lens seems less noticeable than the sight of it, at least in daylight. Digital cameras don't make shutter noise, and camera trappers usually deactivate the cute electronic noises that come with the camera.
  • Most people can't hear the lens murmur inside the case, and it's doubtful many animals can hear it when there is wind, rain or nearby streams. However, some of the latest commercial trail cameras have a tone designed to alert the passing deer, so it pauses for its photo looking like a taxidermic mount.
  • Most mammals can probably detect the camera by scent, at least when downwind.
  • Most mammals and birds seem indifferent to the flash. Like people they sometimes anticipate it and blink, or avert the eyes.

  • Looking at the flash at close range temporarily affects vision by causing image bleaching. That's how it affects people, and it's probably the same for many mammals. The effect is minimal in daylight, but intense in darkness when the pupils are open. The undesirable photographic result is red-eye and disturbance of the subject.
  • You can reduce the effect by using an external flash. If the subject looks at the camera, it won't get a head-on blast of light. If you set the camera for automatic exposure, flash intensity adjusts to the proximity of the subject. If you also set the camera for red-eye reduction a volley of low intensity flashes precedes the flash. This stimulates pupil closure and reduces reflection from the retina.
  • There is no behavioral evidence that the flash affects vision of animals more than it does humans.

Point 2) The response to the flash differs among species, but not all individuals react in the same way.

  • Rodents rarely show any reaction to the camera or flash. They feed, gather seeds, and return to a feeding site despite the flash. Occasionally a wood rat or squirrel will climb on the camera.

  • Birds have wide angle vision, so it is difficult to tell if they are looking at the camera or are viewing a much larger area. They often carry on despite the flash.
  • Deer occasionally show curiosity to a camera, but elk often sniff, lick, or rub antlers on the camera.
  • Coyotes are usually camera shy. You are lucky to get more than one exposure. Yet they may be bold in areas where there are a lot of people who don't harm them, or when scavenging at a carcass in winter. Cliff notes that sound is an important consideration when setting cameras for close-ups. "By setting the camera low to the ground, say under 12 inches and next to some brush, I have been able to get multiple pics of coyotes easily at night or during the day."
  • Bears differ in their response to cameras. In some regions they are indifferent, but in all areas there are curious and destructive bears. We believe the flash stimulates their curiosity. A bear can't play with a mouse without killing it, and can't examine your camera without making permanent adjustments to its workings.

The evidence tells us that camera traps do not hurt wildlife or disrupt the lives of wild animals in any harmful way.


Anonymous said...


Anonymous said...

sooo coaol

Anonymous said...

How do the commercial "Trail" camera's compare with your homebrew camera trap? I am considering another camera because I have the "disease" now and you gave it to me. lol

Camera Trap Codger said...

If you want to buy a commercial cam, I'd suggest one with a removable camera, as in Camtrakker,Pixcontroller, Trailwatcher, or Trailmaster.You can also pick up used home-brew units off the camera trap forums such as Real Deal Hunting Chat or Pixcontroller. Or we can make you another or two. Rich just bought kits from Whitetail Supply and is ready to jump in.

randomtruth said...

Hey Codger,

Great post. As a scientist, I wanna push back a little and am hoping you don't mind the discussion. How do you know that your use of white flash isn't causing animals to change behavior? Couldn't animals be seeing the flash and then avoiding the area thereafter? I.e., you talk about a white flash not being harmful to the animals (and I agree), but not whether or not it's harmful to the study. As I think I've mentioned in previous posts, this is especially important to me because I'm trying to study animal transits and behaviors within a fixed property. Anything that might shift them off the trails or property could corrupt the results (and I would surmise that animals living around humans are even more sensitive than those living in deeper wilderness such as the ones you typically study).

I'm currently using a Moultrie with an IR flash. The quality is so-so, but it definitely doesn't seem to bother even the most skittish coyotes. For example, here's a fun closeup of a coyote pooping on a rock!:


Downsides of the Moultrie... it's slow, pics aren't great quality, and b&w's are, well, b&w, and animals are colorful.

BTW - I noticed that you didn't mention bobcats and cougars. My findings are showing them to be the most shy and likely to change patterns. They seem very sensitive to poorly hidden cameras. I've gotten several shots where it's obvious they've seen or heard the camera and have turned off-trail to avoid it.

Thanks for your wisdom.

Beverly said...

You're nicer than me. To those who complain...I'd simply say:

"I don't gots to show you no stinking badges!"

...and be done with it. Or maybe I'd moon 'em so they don't want to ever come back.

You do good work...don't let the whackos get ya down.

cliff said...

Sorry Codger but I couldn't bite my lip any longer.

Randomtruth, Your findings on bobcats and cougars is entirely wrong. They are not shy, do not change their behavior and are not concerned with a camera that is in plain site. My studies as a non-scientist proves this point. The only thing that will change their habits and location is the food supply.

The trick to getting good photos is to find their food supply at that particular time of the year, the trails they use and set the camera. This takes a lot of work and trial and error, there's no shortcut for good photographs.

Camera Trap Codger said...

Like Cliff, I haven't gotten the impression that the cats are more camera shy than other species. But they are less likely to be encountered than raccoons for example, because there are relatively fewer of them. I believe that if you locate their core area of activity, they will pass the cam more often than otherwise (for example on the fringe of their home range). A friend and I got a pile of photos of a bobcat last spring in San Mateo county -- on three out of four cams. There were also multiple shots per session, especially at the cam that we set at a pool that was frequented by birds. In the case of mountain lion I have gotten as many as 10 to 20 pictures at a time using scent. Other times I have gotten only one or two shots. And using bait you can get a lot more, as has been shown on some of the trail cam forums. In the end what someone needs to do is to design a field experiment using both IR and flash cams. If we could get enough interested camera trappers to cooperate we could do this with a decent sample size and independence of results.

Camera Trap Codger said...

PS -- Random Truth, those are some fine pictures of the coyote. I love action shots like that!

randomtruth said...

Great info guys. I'm not sure on the cats, which is why I asked. I've had an awful time getting pics of them even though I know they're there (scat, kills, etc.). Perhaps the several pics I've gotten of bobcats seemingly turning off-trail to avoid the camera are purely coincidental, and the issue is scarcity over sensitivity. Any other possibilities? Are they more sensitive to human scent - should I be cleaning the camera and area?

BTW - if I didn't make it obvious, I agree with y'all that the white flash and cameras don't harm the animals in any way. They experience numerous unknowns surprises daily and have to adapt to them - what's a camera flash compared to falling trees, lightning, fires, avalanches, ambush predators, or rattlesnakes? I would also expect that any shy animal will quickly acclimate to having a camera around and ignore it (w/ or w/o white flash). Animals are just good like that. Adapt or die.

For general animal surveying, I can't see this potential "acclimation gap" being an issue. But for more focused studies it could be. For example, the black bear that comes through our property seems to have a territory transit cycle of about 2 weeks. If I start using white flash, might she change her path? Permanently? Or maybe it would only cause a blip in her behavior that would average out of any long term transit study.

I could see the same question coming up for scientists trying to use the cams for animal counts or individual IDs too. But again, maybe it would be moot if the camera were left out for long enough. And/or lots of cameras were used. Codger's white v IR study would answer this pretty darn quickly.

Glad you liked the Wile E. Coyote pic Codger. I laughed hard when I saw it on the little lcd screen on the cam. And the kids in the family love it of course. We can't walk by that rock w/o chuckling.

Started using the camera to study if woodrats have any color preference for objects they take, but jays and finches keep taking the colored string! :)

Once again, thanks much for the wisdom gents.

Camera Trap Codger said...

RT -- on the wood rats -- just try aluminum foil for starters. They'll haul it to their stick nests even at considerable distances. (There's a paper somewhere in the Journal of Mammalogy about this as a way of measuring the size of their home range.) They'll stick the foil in the heap of sticks where you can see it, whereas they'll line their nests with the yarn (where you can't see it).

Unknown said...

randomtruth - you are on the money with your comment about lightning.

Over some years of consulting to wildlife scientists and researchers, and supplying custom camera trap systems for their field research, I am constantly asked about the effects of white flash on animal behaviour.

Camera Trap Codger mentioned setting up an experiment using both infrared and white flash cameras - I took a slightly different approach. I have been using an infrared video unit with a wide field of view placed some distance away from the camera trap. The video camera unit triggers as the subject animal approaches the camera trap - and therefore records the actual instant the flash occurs, and the animal's reaction following. Consider it a fly-on-the-wall way of monitoring behaviour before, during, and immediately after the shot is taken.

I am happy to discuss further and provide some clips from my archive as examples...... By the way CTC if you happen to read this - you will know me better as seavisionburma - hope you are well!