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Snow Leopard Update from Dr. Tom McCarthy: Radio noise hampers satellite-based study of snow leopards in Asia

In November 2006 the Snow Leopard Trust initiated the first ever study of wild snow leopards using GPS collars. This study will help scientists understand and save this rare cat which is so secretive it is rarely seen. The collars have a built-in GPS unit that calculates its exact position three times a day. Then every two weeks the data is sent via the Argos system to a researcher's office in Seattle, USA.

However, the study has faced difficulties because the signal from the collar is not being received by the Argos satellites. The signal from the 0.5 watt transmitter is being drowned out by background radio noise of the same frequency, a frequency that is dedicated to Argos satellites. The snow leopard study is not the only one having this problem. Researchers of other animals in much of Central Asia and Europe are not getting data from their collars for the same reason. The area of noise actually spreads across much of Europe and Asia, and the source is unknown. The map below shows the minimum signal power levels that Argos is able to detect above the noise.

In January a new collar was put on the same leopard, but the problem is still occurring. However, the old collar had 80 locations stored on it and researchers were able to download them. The data show an interesting movement pattern for the leopard (see map below).

The old collar is now being tested to see if there is a way to boost the signal so that satellites can receive it. The collar was placed on a captive leopard at the Woodland Park Zoo in Seattle and the strength of the signal from the collar was monitored. The collar is now in the lab being tweaked in the hope of increasing the signal enough for it to be received 450 miles up in space.

Meanwhile, a rare radio signal reached the satellite in June and an email arrived giving four locations for the snow leopard. Although she was expected to be in Pakistan, the signals showed she was actually in Afghanistan, having walked about 20 miles from her capture site and crossed the border! We know her collar will fall off in January and we are waiting to collect it and get the full details of her journeys.

For more information on snow leopards and this study please visit

Story by Tom McCarthy, Ph.D., Science and Conservation Director, Snow Leopard Trust.


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