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Counting Tigers by Their Stripes

Thanks to affordable digital cameras and sophisticated software, conservationists like K. Ullas Karanth of the Wildlife Conservation Society now have powerful tools to accurately monitor tigers in the wild.

In this video, Karanth describes how an earlier method of trying to assess the status of wild populations of the world’s largest cat by peering at fuzzy pug marks in the sand turned out to be not very reliable. Fortunately, a new solution was found to take advantage of what nature has bestowed on every tiger: its own pattern of stripes that can be scanned like a barcode.

 

Each individual tiger has a pattern of stripes unique to itself. Computer programs can match photographs of tigers to known individuals so that researchers can get an accurate idea of how many tigers are in a particular conservation area. Photograph by Michael Nichols/National Geographic Creative.
Every tiger has a pattern of stripes unique to itself. Computer programs can match photographs of the stripes to a database of known individuals so that researchers can know exactly which tigers are in a particular conservation area. From that information, they can also extrapolate what kind of prey base there is for tigers in that area. Photograph by Michael Nichols/National Geographic Creative.

 

Camera traps mounted by Karanth and his colleagues in the Western Ghats, one of India’s last strongholds for wild tigers, make images of the big cats as they steal through the jungle. It’s an unobtrusive and safe way to monitor tigers, even at night. Scientists can then study the images to get a much more accurate idea not only of how many individuals are in an area, but also to assess the condition of each one photographed. They can track the extent of tiger ranges and monitor population shifts, including the arrival of tigers new to an area. By using the data with a modeling system they developed, Karanth’s team can can also help assess the overall health of the ecosystem needed to support that number of apex predators.

“Camera trapping allows us to very accurately monitor tiger populations,” says Karanth. “Find out how many tigers there are, how their numbers are changing, how many survive from year to year, and how many new tigers are entering the population. This is very critical to know whether your efforts to save them are succeeding or failing.”

Identifying tigers by means of their stripes may also prove useful for investigations into wildlife trafficking, particularly if skins seized at international borders or traditional medicine and tourist markets can be identified as cats known to have been living in the wild.

The producer and videographer for this video was Sandesh Kadur, a National Geographic Emerging Explorer who creates award-winning wildlife documentary films and photography books exposing the need to conserve threatened species and habitats around the world. He is also the National Geographic expert accompanying National Geographic Expeditions India Wildlife Safaris.

The video was produced by National Geographic with the support of the World Bank’s Global Tiger Initiative.