A new piece of software which uses 3D coordinates mapped onto a tiger’s body, is able to identify individual tigers by the unique stripe patterns on their coats, similar to a barcode.
Developers say the software will make it easier to estimate tiger populations and aid conservation efforts.
It is also able to match skins sold on the black market to photographs of the animals taken using camera traps.
The team of scientists based in the UK and India report its invention in the journal Biology Letters.
The program was based on software originally designed to scan the markings of grey seals and identify them from photographs.
The researchers adapted this for tiger stripes, and combined it with a 3D map of the surface of a tiger’s body.
This enabled them effectively to unwrap the pattern of stripes from an image of a live animal and match it to picture of the flat skin.
Dr Ullas Karanth, a researcher from the Wildlife Conservation Society India Program, worked on the project with the UK-based company Conservation Research.
“Tigers are very secretive animals and it is a major challenge to estimate their numbers,” Dr Karanth explained.
Over a decade ago, he came up with the idea of using camera traps – hidden cameras operated by trip wires – to monitor tiger populations.
Since then researchers have used a combination of this automated photography – and tagging and tracking the animals – to monitor their numbers.
But each new photograph of a tiger had to be compared with every animal in a database of images. It is a laborious process, Dr Karanth says.
“No piece of software is as good at discerning shapes as the human brain, but we can use this to shortlist the most likely matches, and then eyeball the photos in that shortlist,” said Dr Karanth, “It’s a very powerful tool.”
While they were testing the software, Dr Karanth and his colleagues found images of three tigers that, it turned out, had later been killed by poachers.
This inspired the designers to build in a forensic tool that could be used to trace the origin of any skin to a photograph of the tiger.
They also adapted it for other species with unique markings, including leopards, zebras and salamanders.
Belinda Wright is executive director of the Wildlife Protection Society of India, an organisation that investigates every tiger death in the country.
She says simplifying the process of identifying tigers from camera trap images would be “very beneficial” to conservation research.
But, she warned, opportunities to find the origin of a confiscated tiger skin are rare.
“Skins are often seized in very remote locations, and we often don’t get decent photographs of them,” Ms Wright explained.
Further, camera trapping is not yet carried out continuously in all of the areas throughout India where tigers live.
This will be necessary, she says, to maintain a census of the tiger population.
“Until camera trapping is a regular and ongoing process,” said Ms Wright, “the usefulness of this amazing software will be limited.”