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Bighorn Sheep and the
Wyoming Migration Initiative



Bighorn Sheep on Torrey Rim

March 19th, 2015 was an exciting day for a few bighorn sheep near Dubois, Wyoming. On that day, 20 bighorn ewes in three different locations were captured, weighed, measured, identified, fitted with GPS-transmitting radio collars, relieved of several biological samples for disease testing and released. This collaborative effort involved the Wyoming Game & Fish Department, the U.S. Forest Service, the U.S. Fish and Wildlife Service, the Bureau of Land Management, tribal representatives from the Wind River Reservation, and several volunteers. A new addition to this group that has been managing bighorn sheep in the Dubois area for many years was the Wyoming Migration Initiative (WMI). This operation began a study of bighorn sheep health and migration patterns that is expected to last several years.

Matt Kauffman, Director and Cofounder of the WMI and Kevin Monteith, a Research Associate with WMI and a Research Professor with the University of Wyoming were instrumental in coordinating this event that involved multiple agencies and more than 30 people gathering valuable data for multiple studies.


Using a net-gun from a helicopter to capture bighorn sheep. Use of a helicopter to net-gun sheep allowed for a more individual selection of animals to be tested, in this case just the ewes, unlike previous drop-net captures that were all-inclusive as far as gender and age is concerned. Scientists with the University of Wyoming and the WMI will be correlating body condition with the likelihood of contracting disease. Kevin Monteith provided a new tool, a mobile ultrasound unit that was used to measure the thickness of a ewe’s body fat (an indication of her overall physical condition) and to determine pregnancy. Results showed that only two of the 20 ewes were not pregnant. Their lambing success rate and lamb survival rate will be tracked over coming years. All agencies involved are looking for pathogens the sheep may be carrying. Researchers are involved in ongoing studies of pneumonia and other critical disease factors, particularly the transmission of disease from ewes to their lambs and other members of the herd.


Fitting a captured ewe with a radio collar.

The Mission Statement of the WMI proclaims: Advancing the understanding, appreciation and conservation of Wyoming’s migratory ungulates by conducting innovative research and sharing scientific information through public outreach.
The recent bighorn sheep capture was one of eight ungulate captures in the region conducted by WMI in recent weeks. A migration database is maintained that is accessible through their website. The ewes captured near Dubois were each fitted with a satellite-transmitting collar which is expected to remain active and in place for the next six years. During the first three years, biologists are expecting to recapture these same individual sheep each spring and fall to perform the same round of tests and evaluations. Transmitted data will allow the location of any particular animal at any particular time to be determined. Eventually this data will be available in real time for agency personnel, non-governmental agencies and the public to explore movement among Wyoming’s wild sheep migrations. The migration data collected in this study will be added to the information base “Whiskey Basin BHS Monitoring,” found on the WMI website, which includes data from studies conducted in 2001, 2002, 2004 and 2012.

Releasing a bighorn ewe following data collection.

As the last ewe captured on Sheep Ridge above Dubois bounded off, Greg Anderson, Wyoming Game & Fish Department said with a grin of relief, “We got the data and all 20 Wyoming sheep ran off happy and healthy. That’s a success.”


The staff of the National Bighorn Sheep Center is grateful to have been included in this project and we thank the WG&FD and the WMI for allowing us to see first-hand the efforts involved in conducting field research. If you would like to help us continue to support wild sheep conservation efforts such as this, please consider becoming a member of the National Bighorn Sheep Interpretive Association and supporting our research fund.