Camera Performance: Cameras were deployed for 1141 days (# cameras x number of days deployed). They were in operation for 723 days, or 42.3% of the days they were deployed. False triggers during 24 hr sets were usually responsible for the disparity. False triggers often filled memory cards to capacity and/or drained batteries in a few days.
68% of all photos from 21 comparable 24-hr sets (partial shade to open sky) were probably due mostly to heat-induced false triggers. The range was from 1.5 – 100%. False triggers probably due to rodents accounted for 58% of the photos from 6 night-time sets (range = 17.6 – 69.6%).
A total of 6965 photos were taken. 2977 of these (43%) contained vertebrates (including multiple species). This is equivalent to an overall 2.7 animal photos/24 hr.
Nocturnal versus diurnal activity: We tabulated the number of day and night visits for the 5 carnivores using data from 15 24 hr sets. The sample size is small but shows that with the exception of black bear most visits were nocturnal.
Photo frequency trends during sampling periods: The frequency of photos was not evenly distributed during sampling periods. At many sets more photos were taken during the first week.
Since this could be due to the greater number of cameras in operation during the first week, we plotted the mean number of photographs for rodents, and the trend was still evident.
To determine if this was a response to bait we plotted the mean number of bat photos per day at sets used as night roosts. Bait is not an attraction to these insectivorous bats. The correlation coefficient of 0.073 was low, and the slope was reduced.
The disappearance of bait is the most likely explanation for the declining visitation rate of rodents and also perhaps for some mammals other than bats.
Neither coyote nor bobcat showed the distinctive decline in photo frequency shown by rodents.
The daily distribution of visits by coyotes however shows a different pattern. At 10 camera sets low visitation prevailed most of the time, and highest visitation peaked between weeks 2 and 3. This is what Larrucea and her co-workers found: coyotes don't rush in to visit new cameras.
Bobcats showed two peaks of visitation during the first 2 weeks, but the pattern is not well defined.
Visitation data will increase in the coming months, and differences among species should become clearer.
Hey!! Don't tune out yet!
More graphs are coming, and after that you get to see photos from the cameras Craig just checked (including a new carnivore!).