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Bighorn sheep continue to succumb to pneumonia



Nevada Department of Wildlife (NDOW) biologists continue to find bighorn sheep that have died due to complications brought on by pneumonia in the East Humboldt Range and in the Ruby Mountains.  

“We have found 61 dead bighorn sheep in the East Humboldt’s and 18 in the Ruby Mountains for a total of 79 sheep over the last three months,” said Caleb McAdoo, NDOW big game biologist.  “In other words, we have observed mortalities of 31% of the herd in the East Humboldt’s and 11% of the herd in the Ruby Mountains.”

McAdoo cautions the public that the full extent of the effects of the disease event won’t be known until later in the spring when aerial surveys of sheep populations are performed.  Biologists anticipate that the magnitude of the die-off may be much greater than presently known.

According to McAdoo this isn’t uncommon as other states around the west, including Washington, Montana, and Utah, have also experienced die-offs in their wild sheep populations due to the effects of pneumonia.  During the winter of 1995-1996, the Ruby Mountain sheep herd lost approximately 80% of its population due to pneumonia, though this is the first major disease event in the East Humboldt’s since bighorns were reintroduced there 18 years ago.  Recently, 95% of the Hays Canyon herd in northwestern Nevada was likely lost to a pneumonia outbreak.

“Unfortunately, there is no known cure, treatment or protocol for pneumonia in bighorn sheep,” said McAdoo, “but we are going to use the data collected from this disease event which may help in future outbreaks.”

NDOW biologists and veterinarians have been performing a number of tasks, setting the stage for future study.  This includes tagging and putting radio telemetry collars on sheep in both herds, taking biological samples from both live and dead sheep, and administering Draxxin, a broad spectrum antibiotic to more than 60 sheep.  Soil and forage samples are also being taken to explore what effect forage quality and trace minerals in the forage may have on both diseased and healthy animals. 

Over the next few years NDOW biologists will follow the collared and tagged animals observing overall health, lamb recruitment and herd growth in an effort to understand the long term affects a major disease event has.  Biological samples taken from deceased animals will be compared to those taken from healthy animals to see if minerals, forage quality or even genetics may play a role in determining which animals may live and which may die. 

To avoid putting more stress on the animals than necessary, work is being done from the ground as much as possible, as helicopters cause the animals to try to evade and escape, using precious energy and making them more susceptible to pneumonia. 

The full extent of the die-off will not be known until later in the spring after the sheep have had time to recover from the winter and can be surveyed from the air. 

So far only one Rocky Mountain goat has been found that has died from pneumonia.  It is too early to tell if a large percentage of the goat population has also been affected by pneumonia.  One good sign is that a fair number of kids have been seen on surveys.  Kids are often one of the first segments of the population that are affected by major disease events.

McAdoo also wanted to recognize the sportsman’s groups that have assisted in funding the operations. “The cost for all the tagging, collaring and sampling work is very expensive,” McAdoo explains.  “Elko Bighorns Unlimited (EBU) and Nevada Bighorns Unlimited (NBU) stepped up to the plate and are helping us out in these hard economic times and we thank them for that.  NBU is donating $25,000 and EBU has provided $27,000 with the offer of more if needed.” 

The Nevada Department of Wildlife (NDOW) protects, restores and manages fish and wildlife, and promotes fishing, hunting, and boating safety. NDOW’s wildlife and habitat conservation efforts are primarily funded by sportsmen’s license and conservation fees and a federal surcharge on hunting and fishing gear. Support wildlife and habitat conservation in Nevada by purchasing a hunting, fishing, or combination license. For more information, visit www.ndow.org.

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