Learn More:

Alexander Center For Applied Population Biology

Camera-Shy Cats

To study wild jaguars, those masters of stealth, requires a good deal of patience and ingenuity on the part of researchers. Traditionally, scientists have relied on analyzing evidence jaguars leave behind—scat, fur, paw prints, claw marks, and animal remains. But with the help of Lincoln Park Zoo’s Field Conservation Funds, two teams of researchers, one in Argentina headed by Mario di Bitetti, Ph.D. and one in Brazil headed by Laury Cullen, Ph.D. are using cameras to “trap” the elusive big cats. Lincoln Park Zoo scientists will then use the trap data to develop a model of the jaguar populations in those countries.

The camera trap is an elegantly simple device. Two cameras are positioned on
either side of a path or stream and fitted with heat or motion sensors. Whenever the sensor detects heat or motion, the cameras are triggered and take a photo—one of each side of the jaguar. Because the spots on a jaguar are as unique as a human’s fingerprints, and different on both sides of the animal, the photos enable researchers to distinguish between individual jaguars as they are “trapped” by the camera.

Who's who?
	Field biologists Augustine Pariolo and Carlos DeAngelo use camera traps to identify individual jaguars by their unique coat pattern. Can you tell these cats apart? Click here for answer.

Faced with trapping hundreds of square miles of jaguar territory using only a few dozen camera traps, scientists determine a small number of “high traffic” locations to place the traps. “Then, using sophisticated statistical software, we can extrapolate data about the few locations to the larger territory,” explains Lincoln Park Zoo Post-doctoral Research
Associate, Eric Lonsdorf, Ph.D. “For example, from the 18 photos of jaguars caught in camera traps we may identify only five unique individuals in our study areas, but we can infer that perhaps 95 jaguars live in the study area.” Knowing how many animals live in an area is key to projecting the future of the population.

One problem with the camera-trap method is that the cameras are triggered whenever anything passes by the sensor, not just jaguars. But this, says Joanne Earnhardt, PhD., director of the Alexander Center for Applied Population Biology, has provided “an unexpected treasure trove” of data for scientists because caught on film are species scientists had no idea were living in the forest at all. “And,” she adds, “many photos have no animals
or animals fading into the forest—just like my vacation photos.”

Just how easy is it to identify jaguars by their spots? Earnhardt and Lonsdorf have initiated a research project to find out. Using photos of captive jaguars living in zoos, the pair will test jaguar experts’ ability to correctly identify individual jaguars by their photos alone. Because the identities of the captive jaguars are known to Earnhardt and Lonsdorf, the pair will be able to determine when even the experts get it wrong. “We want to know when people are likely to misidentify an animal,” explains Earnhardt. “Is it harder to identify male or female jaguars? What features lead to the misidentification?”

Although there are other ways to identify individual jaguars—radio collaring for example—these methods don’t yield the kind of data needed to answer questions about the population as a whole. In the case of radio collaring, a much more expensive and difficult procedure, information is collected about an individual animal’s movements and range, but not how many animals are living in one area, their age or sex. Without being able to infer the size and makeup of the population, scientists cannot determine its likelihood of survival. By incorporating camera-trap data into their population model, scientists can make better decisions for the sake of those camera-shy cats.