Conservation Explores Imaging Technology for Tiger Traps

Several spatial capture-recapture (SCR) camera models have been developed to estimate animal abundance by analyzing the detections of individuals in a spatial array of traps, according to the Wildlife Conservation Society.

Most of the models do not use the actual dates and times of detection, even though this information is readily available when using continuous-time recorders such as microphones or motion-activated cameras. Instead, most SCR models either partition the period of trap operation into a set of subjectively chosen discrete intervals and ignore multiple detections of the same individual within each interval, or they simply use the frequency of detections during the period of trap operation and ignore the observed times of detection. Both practices make inefficient use of potentially important information in the data.

A tiger photographed by camera-trap. Courtesy of Ullas Karanth/WCS.

A new study led by Robert Dorazio of the United States Geological Survey and co-authored by the Wildlife Conservation Society's Ullas Karanth, however, finds that dates and times of animal detections are often not factored into the analysis. This is despite the fact that this data is available when using "continuous-time" recorders such as camera-traps.

"Modeling capture times of tigers and other large carnivores uses all of the information in the data and gives us a chance to learn more about the behaviors and movements of these animals — information that is crucial to their conservation,” Dorazio said.

"We are now able to exactly incorporate the time of capture into the data analysis,” Karanth said. “This gives us more power to mimic nature in the sense of how tigers actually get trapped in cameras and how their movement, behavior and space-use relate to time. This is a significant advance."

Because 70 percent of wild tigers are concentrated in <6 percent of remaining habitats, it is critical to efficiently manage these areas for tiger use.