The cat's out of the bag—or, should we say, the mountains.

Notoriously elusive snow leopards have been caught by a camera trap in northern Pakistan as part of a three-year study by scientists with the Norwegian University of Life Sciences. The main collaborator in the study is the Snow Leopard Foundation Pakistan.

With only half a year left to complete their study, the scientists published a report on their use of camera traps in the journal Methods in Ecology and Evolution.

Snow leopards (Panthera uncia), which live in the snow-capped mountains of Central Asia, are known as "gray ghosts" or "ghost cats" because they frequently hide from people and other animals.

But researcher Richard Bischof is hoping to shed more light on the shy beast by leading a non-invasive study of snow leopards using scat analysis and photography. (See snow leopard pictures in National Geographic magazine.)

"You can garner lots of information from these images, including insights into distribution and behavior, etc.," Bischof said.

Unique coat patterns of the spotted cats also allows the identification of individuals and aid estimation of population size.

There are an estimated 4,000 to 6,500 snow leopards in the wild, and the species is listed as endangered by the International Union for Conservation of Nature.

That's why big cat conservationists are studying the leopards in an effort to learn more about them and keep them from going extinct. (Read about National Geographic's Big Cats Initiative.)

View Images PHOTOGRAPH BY RICHARD BISCHOF, NORWEGIAN UNIVERSITY OF LIFE SCIENCES AND MUHAMMAD ALI NAWAZ, SNOW LEOPARD FOUNDATION PAKISTAN

Cats on Camera

Photographing snow leopards has a storied history: In November 1971, National Geographic magazine published the first ever pictures of snow leopards in the wild—photographed also in Pakistan.

The article, called "Imperiled Phantoms of Asian Peaks," followed well-known zoologist and photographer George Schaller in his pursuit to photograph the legendary cat.

More than 40 years later, it's not much easier to capture the cats on camera.

View Images PHOTOGRAPH BY RICHARD BISCHOF, NORWEGIAN UNIVERSITY OF LIFE SCIENCES AND MUHAMMAD ALI NAWAZ, SNOW LEOPARD FOUNDATION PAKISTAN

"We are working in very remote areas, at high elevation, and in rough terrain. This brings along a lot of challenges but also makes our work a fantastic adventure. Non-invasive methods such as camera traps and scat-based DNA analysis allow us to study this secretive carnivores in their mountain environment," Bischof said.

The project would not be possible without the support from local communities, wildlife agencies, and conservation organizations.

"Most importantly, I am working with a skilled team of Pakistani biologists, which are now experts at camera trapping carnivores."

The team has learned that if they place the cameras in random locations, they have a poor chance of getting snow leopards on camera.

View Images PHOTOGRAPH BY RICHARD BISCHOF, NORWEGIAN UNIVERSITY OF LIFE SCIENCES AND MUHAMMAD ALI NAWAZ, SNOW LEOPARD FOUNDATION PAKISTAN

"Once we detect sign of carnivores, such as tracks, we'll study the local area in an attempt to maximize our chance of photographically capturing the animals," he said. (See "Snow Leopards Need To Be Protected ... But How?")

The team has been placing cameras in the pathways of traveling snow leopards, which is how they got these amazing photos.

"We use digital cameras with a motion sensor and an infrared flash to take photos both during the day and at night. Often people that use camera traps can set [them] in trees. We don't have any trees at high elevation. So we use steel poles and attach the cameras to them."

The snow leopard shown in the series of photos "saw the pole with the camera and walked right up to it, looked into the camera, and then walked past it."

View Images PHOTOGRAPH BY RICHARD BISCHOF, NORWEGIAN UNIVERSITY OF LIFE SCIENCES AND MUHAMMAD ALI NAWAZ, SNOW LEOPARD FOUNDATION PAKISTAN

Poop Data

Bischof's team has also been collecting snow leopards scat for DNA analysis. The data will reveal more about the status and ecology of carnivores in their study region.

View Images PHOTOGRAPH BY RICHARD BISCHOF, NORWEGIAN UNIVERSITY OF LIFE SCIENCES AND MUHAMMAD ALI NAWAZ, SNOW LEOPARD FOUNDATION PAKISTAN

"Admittedly, a photo of snow leopard is more glorious than a piece of scat. However, genetic methods allow us to extract a lot of information from scats, including the species and the sex of the animal, its individual identity, and even its diet. Combining camera trapping and genetic sampling will give us a more comprehensive picture of carnivore ecology in our study area."

View Images PHOTOGRAPH BY RICHARD BISCHOF, NORWEGIAN UNIVERSITY OF LIFE SCIENCES AND MUHAMMAD ALI NAWAZ, SNOW LEOPARD FOUNDATION PAKISTAN

"Camera trap photos of wildlife capture people's imagination. That in itself is valuable, as it can help raise awareness. For wildlife ecologists, camera traps and other non-invasive methods are a valuable source of data that can help us learn about the ecology, and ultimately better conserve, secretive wild species."