Over the last 30 years a lot of what researchers have learned about snow leopards has come from collars attached to the cats. Although this is invasive for the individual cats concerned the data has changed our knowledge of what snow leopards can do.
But how do these collars work and how long have they been used by snow leopard researchers?
Radio collars, also sometimes called VHF (Very High Frequency) transmitters emit radio signals which are picked up with a hand held receiver connected to an antenna. Generally they can be heard within a distance of 12 -15 km if weather is good and you have line of sight. However if you are following a snow leopard chances are you are in very mountainous terrain and the signal may be difficult to trace. These collars also don’t work if cats roam a long distance which is often the case with snow leopards that can move over 100km in a few days.
Satellite collars on the other hand send signals even in extreme weather and from great distances via satellites which orbit the earth and scan for these collar signals. Researchers’ computers are able to find the exact location of the snow leopard and plot his/her movements over many months as long as the cat has not lost the collar and the batteries still work. Collar signals may also reveal when a cat stops moving either for feeding on a kill for a few days, preparing a den for births or because the cat has been injured or died.
Satellite collars are ten times as expensive as conventional radio collars (between $2000 and $3000).The technological development in new collars now means that they last much longer and can do more than the early collars. The Global Positioning System (GPS) unit calculates the exact location of the collar on an hourly basis and stores the information in the collar. The Lithium–ion battery is designed to last at least 18 months.
Although information is sent via email researchers also need to retrieve the collars after they drop off the cat at a designated time, usually after a year. Cats don’t suffer with the collars, can still hunt, mate and breed with them, but researchers will never leave a collar on for more than about a year.
Dr Rodney Jackson, the world’s foremost snow leopard expert and Founder and Director of the Snow Leopard Conservancy, was the first ever to radio collar cats in Nepal in the early 1980’s. He called this first cat “Ek”, the Nepali word for ”One” and throughout Nepal’s most severe winter he captured and collared another five cats. He not only proved it was possible to capture snow leopards, immobilise them safely and collar them, but to also get unique and useful data this way.
The first ever cat fitted with a GPS satellite collar was Bayad-e-Kohsaar (Urdu for “In Memory of the Mountains”). Bayad as she was known was collared in Chitral Gol National Park in northern Pakistan on 17 November 2006. A team headed up by Dr Tom McCarthy from the Snow Leopard Trust worked with Pakistan’s North West Frontier Province Wildlife Department and WWF–Pakistan.
Bayad is known to many viewers around the world from footage in the BBC’s Planet Earth TV documentary. Her movements were tracked for 14 months and yielded more data than ever before with the use of radio collars. Bayad was recorded as she moved, rested and slept for those months until the collar was programmed to fall off. When the collar dropped in January 2008 it wasn’t found by the researchers for two months due to the incredible remote and steep terrain. The team only found it after building their own device with an old FM radio. Bayad had dropped the collar inside a deep crevice at Shali Gol, the buffer zone of Chitral Gol National Park.
During her time with the collar Bayad moved from Pakistan over the border into Afghanistan. Although some data was received for a few months no signals were received due to severe noise interference but enough signals came through to enable the research team to follow some of her movements.
Dr McCarthy said, “The collar could hold between 500 and 1,000 GPS location coordinates, which sheds light on the behaviour of an animal that is notoriously difficult to study. It will show us her range, how far she moved in an 8 hour period, in a month and whether she got close to humans in her travels.”
Today organisations like the Snow Leopard Trust and the Snow Leopard Conservancy continue to work with this amazing technology which will help in the race to save the endangered snow leopard.