Tracking Movements of Domestic Sheep with 
the Global Position System --
an Application for Public Land Managers
Mark Moulton
Fisheries and Watershed Program Leader
Seth Phalen
Range Management Specialist
Sawtooth National Recreation Area, Idaho

March 18, 2002

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Executive Summary


Features of Unit Tested

Setting for the Test


Data Summary


Acknowledgements &
Further Information

Executive Summary

A core objective of most allotment management plans on public lands administered by the U.S. Department of Agriculture (USDA) Forest Service is the movement and use of permitted livestock to achieve the resource objectives desired, and/or prevent conflicts with other uses.  However, monitoring and documenting livestock movements and use through a grazing season is  expensive and difficult, typically requiring several field reviews by qualified resource specialists. This demonstration project evaluated the use of the Global Positioning System (GPS) to achieve these monitoring objectives on sheep allotments.
The cost, size, and accuracy of GPS have all converged in recent years to make their use for tracking animal movements practical. During the summer of 2001 movement of a herd of sheep grazing in the Smiley Creek Sheep Allotment within the Sawtooth National Recreation Area (NRA) in Idaho, was recorded using the GPS_2200L datalogger. 
Two sheep within the band were collared. The very high frequency (VHF) /GPS datalogger collars are designed and sold by Lotek Wireless Inc. of Ontario, Canada. This report addresses the procedures and success of applying the technology. The underlying science of GPS is not presented.

Both collars performed without compromise for 128 days between early June and mid-October, 2001. Ninety-four percent of the position attempts were successful over the period despite the mountainous and forested conditions. Launching and retrieving the data was less than intuitive, as with many new technologies; but once understood, the process was effective. The final data product includes animal positions, which are date and time stamped throughout the grazing season. 

The two collars were launched with different sampling frequencies every two hours with one,  and every four hours with the other. Although a finer temporal resolution provides greater route detail, further analysis will be required to determine if the added detail is meaningful for day-to-day allotment management. Memory capacity of the collars could have easily accommodated an even more frequent sampling.