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This blog is predominately about camera trapping in California. We camera trap to save our souls and to teach primary school students about biology and conservation. We will also touch on other camera trapping news and musings, sets from afar, mediocre herpetology, sucky birding, and other natural history discussions.

Tuesday, January 11, 2011

Bobcats Week 2

I previously posted some bobcats from the first week of a set in Santa Cruz County, CA.

The set was up for a total of 15 days and bobcats showed up during the second week too.

In two weeks we had 12 visits with 13 bobcats total.  One visit had two bobcats in the same visit.  In the 12 visits there are at least two individuals, but likely three.  I don't think there was any more than three bobcats captured at this set.  The time between visits ranged from 1.5 hours to 100 hours with a mean species visit interval of 33 hours.  I define a visit as >1 hour between images of the same species.  Visits were split roughly evenly between day and IR images.  This was a well lit set so IR correlated well with the sun being below the horizon.  Below is a graph of the visits binned into hour intervals for bobcats and coyotes for this set, with yellow being daylight hours and gray being night hours. Clicking on the graph will enlarge it.

Some data of interest for this set is as follows:
Data of Interest
# of pics 68
# not "test" pic 52
# of ID species 9
# of CT days 15
# of visits 26
# of misfires 5
# of test shots 16
# of triggers 52
Pos triggers 47
Pos trig % 90.4
Neg Trig % 9.6
visits/CT day 1.73
trigger/CT day 3.5
Pos trigger/day 3.1
IR images 24
Color Images 28
# of indiv 36
# of birds 15
# of mammals 32
# or small mammals 0
# of med mammals 31
# of lrg mammals 1

The number of birds, small mammals etc are the number of images not visits.  I still have to work out the complicated excel equation to get more precise visit data grouped by type of animal. Complicating the equation is if there is more than one animal in a visit, for example gangs of raccoons.  In that case, I think the total would be more informative as four "individual raccoons" rather than one "raccoon visit," but hopefully I will have that worked out shortly.

I did not ID all birds in this set hence the number of ID species being lower than it could be.  I will discuss the birds of this set once I finish IDing some of the Little Brown Birds.  With almost 2 visits a day and a positive trigger percentage over 90% I was quite please with this set despite the very heavy rain that occurred throughout most of it.  Bobcats were the most frequent visitors, followed by birds in general and then raccoons and coyotes.

The non-bird species list at this set was Bobcat, Coyote, Raccoon, BT deer and Striped Skunk.

The IR flash seems to be worse and blowout even more in wet conditions so this first photo is even worse than normal but shows two bobcats.  The previous photo in the series had the bobcat at the top of the slope in a crouched laying down position while the second one was just coming into frame at the bottom of the slope as if waiting in ambush.  I like to think it was the youngster getting ready to play attack mom.  I am going to have to do like the Codger and try and dim my IR flash a bit.  Maybe RandomTruth's upcoming post may have some more ideas on doing this.

Ambush Averted

Going on an afternoon hike


  1. Must be moisture in the air that lights up on wet nights.

  2. I also wonder if there is condensation on the IR flash itself or the lens contributing to the enormous blow out. I am thinking of pulling this cam and try and improve the IR in the backyard in the next week or so.

  3. Cougars may be the big score, but I am always happy with bobcat shots. My tidbits...

    The enhanced blowout is prob because everything is wet - shiny/reflective surfaces really blowout in IR. Slick manzanita trucks show as stark bone white.

    Like Codge, I've found that I can use the polyprop packing foam to diffuse the IR flash enough to eliminate blowout for 8-foot, and even 4-foot camera distances. BUT, the focus/quality of the fixed lens trail cameras at those distances is sooo terrible (especially at night), that it's kind of a waste of time. Which is likely why the manufacturers use such a strong flash, and don't give low, medium and high settings, or such. Because the cams are made for deer-sized critters at 12-20 feet.