Lab’s Probe of Bighorn Sheep Typifies Its Pioneering Work
When the carcasses of six bighorn sheep were discovered on the eastern slopes of 9,710-foot Warner Peak in Modoc County last week, they were airlifted off the mountain by helicopter and trucked to the State Fish and Game Department’s Wildlife Investigations Laboratory in this Sacramento suburb.
Since October, 11 California bighorn sheep in a herd of 49 have been found dead of pneumonia, a serious development considering that only 350 of this rare subspecies of high mountain bighorn sheep exist in the state.
Scientists hope that the bodies flown off Warner Peak will provide the answer to whatever was causing the epidemic. Similar outbreaks of pneumonia periodically decimate bighorn sheep herds. Last year, for example, pneumonia wiped out 85 of the 120 animals in Oregon’s premier Rocky Mountain bighorn sheep herd, including the largest ram ever recorded in America.
Carcasses to Be Studied
Biologists here at one of the leading research and treatment centers for wildlife diseases in the world will perform necropsies on the sheep carcasses.
“Like humans, animals and birds are also subjected to outbreaks of infectious diseases,” explained Bill Clark, 46, director of the wildlife investigations lab.
“We are responsible for wildlife disease research and treatment, for the development of preventive medical protocols, for new vaccines, for the development of wild animal capture techniques including drugs to reduce losses and for forensic work in the illegal taking of wild animals in California.”
Veterinarian David Jessup, pathologist in charge of the lab’s wildlife disease investigations for 11 years, noted similarities in the pneumonia deaths of desert bighorn sheep lambs in the Santa Rosa Mountains near Palm Springs.
For the last 10 years the mortality rate among the lambs has averaged 90% a year, he noted.
Fish and Game officials hope to solve the problem with a vaccine, developed by Jessup, encapsulated into a tiny bullet tested in captive animals.
“The bile-absorbable bullet with modified live vaccine is so tiny it weighs almost nothing. We are planning to shoot the vaccine into 100 to 150 of the adult sheep in the herd next month from distances of 20 to 30 yards,” Jessup explained.
“That way we will avoid the trauma and the expense of catching the animals to immunize them. Pneumonia hasn’t bothered the adults in the herd. The vast majority appear healthy. The vaccinated adults will shed the modified live virus and hopefully by contact immunize the lambs.”
The sheep investigation is typical of the scientific investigation the lab has pioneered since its creation in 1941. Currently, 14 people work at the lab, which has an annual budget of $350,000.
Another program is a $40,000 study of blue tongue disease among deer. Last year, between 5,000 and 8,000 deer died of the ailment in five Northern California counties.
“Blue tongue came into this country about 40 years ago, probably carried by Santa Gertrudis cattle imported from Africa,” Jessup said. “It often occurs when deer gather at stagnant ponds and is spread by a particular species of gnats.”
Other studies at the lab include that of avian cholera, which has already killed 20,000 wild fowl this year in California. Fish and Game staff have been spending a great deal of time fishing dead birds out of lakes, ponds and reservoirs and burning the carcasses to stem the spread of the disease.
“Infectious diseases spread rapidly through bird flocks. You see thousands of birds out there on a lake seemingly in the peak of health one day. The next day hundreds of them are dead. In 1940 as many as 250,000 were killed by water fowl botulism at Tulare Lake alone,” Director Clark said.
Pelican, Owl Deaths
Jessup, veterinarian Dave Hunter and others at the lab are now investigating die-offs of several hundred pelicans along the coast from Santa Barbara to Monterey and losses of rare spotted owls and sandhill cranes.
Workers at the lab have other duties, as well.
Zoologist James Banks is a wildlife criminologist. His office is filled with eagle skulls, bear gallbladders, mountain lion teeth and an assortment of bones, wings and beaks of various birds, all evidence of poaching.
Banks, 49, a former detective for the state Department of Justice, has been tracking down poachers for Fish and Game for 14 years now.
The lab also has done pioneering work on capturing animals in the wild and transferring them to new ranges.
“Capturing and handling techniques that have come out of this lab are now in use throughout the world,” according to Clark.
Finding Carcasses Difficult
In the case of the bighorn sheep deaths, the work going on now may only be the beginning. But even locating the carcasses is a problem.
“We flew 10 hours in the helicopter trying to locate the rest of the herd without success,” said Banky Curtis, 40, Fish and Game Wildlife supervisor for Northern California. “It is extremely rugged country covered with snow. The dead animals were at the 7,000- to 8,000-foot level. We don’t know whether the other sheep are dead or alive. We may not know until spring.”