Bighorn ewes

Sportsmen’s Dollars Support Research on Desert Bighorn Sheep

Thanks to California’s big game hunters, wildlife biologists studying Desert Bighorn Sheep will have new technology and tools to help them study deadly diseases that affect these icons of the desert.

In 2013, Desert Bighorn sheep populations in the Mojave Desert near Old Dad Peak suffered a die-off. In an effort to learn more about the spread of disease and survival, scientists from the California Department of Fish and Wildlife (CDFW), Mojave National Preserve and Oregon State University launched an ongoing joint study of adult sheep. They have captured and radio-collared about 150 adults to date, but important data about lamb mortality is still missing.

Now, in the third year of the study, a grant will enable researchers to collect the data that will unlock the mystery. Beginning this winter, scientists will capture and radio collar bighorn ewes. As they are captured, ultrasounds will be conducted, and ewes that are found to be pregnant will be implanted with special vaginal implant transmitters, the purchase of which will be funded by the $190,000 grant. When the lamb is subsequently born, the transmitter will be pushed out and send an alert signal. Project researchers can then go to the birth site and put a miniature radio transmitter on the lamb.

If the lamb subsequently dies, a mortality signal will be transmitted and the body will be recovered by researchers quickly enough to pinpoint the cause of death. This real-time information gathering technique will hopefully provide answers to the mystery behind unexplained bighorn mortality — why the 2013 disease outbreak was so widespread, what factors contributed to the spread of the disease and what management efforts can be instituted to help prevent future outbreaks.

Spearheaded by the nonprofit California Chapter of the Wild Sheep Foundation and Oregon State University, the study will greatly benefit from the addition of the new technology, made possible by the purchase of big game tags by California hunters.  It is one of many project funded by the Big Game Grants Program, which allots about $800,000 each year to support studies such as this one.

Joint projects are particularly critical to fund, because they help target wildlife management issues which are often beyond the normal scope of CDFW manpower, expertise or financing.

“Funds in the Big Game Grants Program support a wide range of wildlife studies and projects,” said Craig Stowers, CDFW Big Game Program Manager. “We have a responsibility to see that the funding generated by hunters goes toward preserving wildlife populations. This sheep study is a great example of how hunters play a role in solving complicated and challenging research needs.”

This new phase of study is hoped to produce critical information unavailable until now.

“The desert environment is harsh and expansive. Until now, it’s been almost impossible to find and collect dead lambs in a timely manner, which is necessary in order to determine the cause of mortality,” said Daniella Dekelaita, a doctoral student and researcher at Oregon State University. “We know there have been significant lamb losses in some herds and this will give us accurate and timely information on what was the cause.”

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Media Contacts:
Regina Abella, CDFW Wildlife Branch, (916) 445-3728

Harry Morse, CDFW Communications, (208) 220-1169