By JANET ZIMMERMAN, STAFF WRITER
Press-Enterprise
A pneumonia epidemic that has killed more than 100 bighorn sheep in the Mojave National Preserve this summer and is decimating another herd may have come from sick animals illegally dumped off a truck en route to alfalfa fields in the Imperial Valley, federal land managers said Tuesday, Sept. 3.
Scientists are investigating two areas plagued by disease. The first, at Old Dad Mountain, is 15 miles southeast of Baker. Wildlife experts estimate that half of the 200- to 300-sheep herd has died there and at nearby Kelso Peak since mid-May.
Last month, several sick bighorn sheep were found 35 miles to the south in the Marble Mountains, which are just south of Interstate 40 and east of Kelbaker Road. Tests showed they suffered the same strain of pneumonia found in bighorn at Old Dad Mountain and Kelso Peak.
“They’re seeing a lot of sick sheep, so they’re expecting a lot of sheep to die in the next couple weeks in the Marble Mountains. It happened pretty quick at Old Dad, within a month,” said Linda Slater, spokeswoman for the 1.6 million-acre preserve.
The majestic bighorn, icons of the American West, are highly susceptible to pneumonia carried by domestic sheep and goats. Bighorn have no immunity to the disease, which is almost always fatal.
At first, wildlife experts feared the pneumonia was transmitted between the herds and would quickly spread. But a recent discovery may be a clue to the source of the outbreak and its transmission, she said.
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On Aug. 24, scientists also found pellets at Foshay Pass, 15 miles northeast of Interstate 40 and Kelbaker Road. They are waiting for test results to determine whether the droppings came from domestic sheep, Slater said.
Trucks regularly transport domestic sheep through the Mojave on their way from Montana to Imperial Valley and around the Salton Sea for grazing, Slater said.
“The scientists are speculating that perhaps a truckload had some sick sheep on it. Maybe (the driver) had to unload some sheep to get some dead animals off the truck” and that’s how pellets got on the ground, she said.
The case is still under investigation and law enforcement is not involved, she said.
Early on, biologists thought that a feral angora goat shot by a hunter last fall at Marl Spring, 12 miles east of Old Dad Mountain, may have been the source of the outbreak. Though the animal tested negative for pneumonia, it still could have been a carrier, Slater said.
Later this month, the California Department of Fish and Wildlife is expected to conduct a count by helicopter. The numbers of bighorn will be compared to population figures from the last survey, in 2008.
In October, state and federal officials plan to capture healthy animals in the surrounding mountains and outfit them with GPS collars so they will know immediately if they go down. At the same time, they will be able to collect blood samples and nasal swabs to see if the infection has spread.
There is no vaccine or cure for pneumonia in bighorn sheep. The disease does not spread to humans.
Some of the dead animals were taken for testing to the California Animal Health and Food Safety Laboratory in San Bernardino, which is operated by the UC Davis veterinary school. Some carcasses were too decomposed for testing and were left in the field, state officials said.
Before the outbreak, there were an estimated 425 to 750 bighorn in the five groups in the Mojave: Old Dad Mountain, Clark Mountain, Piute Mountain, Woods-Hackberry Mountains and Providence-Granite Mountains.
State officials have yet to decide whether to proceed with this year’s bighorn hunting within the preserve, which starts Dec. 1. The Mojave is one of the few places in California where bighorn sheep hunting is permitted.
In October, the Fish and Game Commission will consider what to do about the upcoming hunting season. The state issues tags by lottery, based on the number of rams in a herd; three were issued this year for the Old Dad Mountain and Kelso Peak area.