BY JANET ZIMMERMAN
Riverside Press-Enterprise
State and federal wildlife experts will launch a $48,000 helicopter survey and GPS tracking effort this weekend to gauge the scope of a pneumonia epidemic that has killed more than 100 bighorn sheep in the Mojave Desert.
The outbreak has decimated two herds, one around Old Dad Mountain in the Mojave National Preserve and a second in the Marble Mountains, 35 miles south. Officials have said the highly contagious infection may have come from sick domestic sheep illegally dumped off a truck en route to alfalfa fields in the Imperial Valley.
The National Park Service and California Department of Fish and Wildlife will begin their four-day investigation on Sunday, Nov. 3, said Debra Hughson, science adviser for the preserve.
“We are throwing everything we have at this to better understand it and hopefully control it,” she said.
The crew of a federally contracted helicopter will search for the scattered animals over as much as 80,430 acres, in areas where dead and sick bighorns have been found and in nearby mountain ranges.
The helicopter can fly seven hours per day, at $1,600 per hour, paid for by the National Park Service, Hughson said.
Individual animals will be captured with a net fired out of the low-flying helicopter. The bighorn is then removed from the net, blindfolded to reduce stress and hobbled with a leather restraint to prevent kicking, she said. The workers take blood samples and a nasal swab, attach the collar and release the animal.
The Department of Fish and Wildlife is providing 54 GPS collars that transmit information daily by satellite. If an animal stops moving, the collar sends out a mortality signal so that experts can quickly locate the carcass and take samples, Hughson said. The GPS collars work for four years.
After the GPS collars are gone, high-frequency radio collars will be used for any remaining animals that are located, she said. The radio collars have a longer battery life and are less expensive, but readings require a fixed-wing aircraft or people in the field with antennas, instead of a satellite.
“The idea here is to have collared animals in the surrounding mountain ranges so we can have an early warning of the spread of the pathogen,” Hughson said. “We can get a better understanding of the progression of the disease, its spread and impact on herds.”
Biologists, veterinarians and other staff will help with the field operation. If an obviously sick animal is captured, a veterinarian may decide to kill it and perform a field autopsy, Hughson said.
Experts don’t know exactly how many animals have died, mostly because they spread out as water sources become more plentiful this time of year, she said.
The first dead animals were found in mid-May at Old Dad Mountain, 15 miles southeast of Baker. The disease has killed about half the 200 to 300 sheep in the herd there and at nearby Kelso Peak.
In August, several sick bighorn sheep were found in the Marble Mountains, which are just south of Interstate 40 and east of Kelbaker Road.
Tests showed they all had the same strain of pneumonia. The disease is carried by domestic sheep and goats; bighorn have no immunity and almost always died of it. There is no vaccine or cure for pneumonia in bighorn sheep. The disease does not spread to humans.
State officials have decided to proceed with this year's bighorn hunting within the Mojave National Preserve, one of the few places in California where it is permitted, said Regina Abella, desert bighorn sheep coordinator at the state Department of Fish and Wildlife.
The state issues a limited number of tags by lottery, based on the number of rams in a herd; last season, three tags were issued for the Old Dad area. The season starts Dec. 1