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Encampment bighorn sheep project

February 14, 2020
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Ten bighorn sheep ewes in the Encampment herd were sampled for disease and fitted with GPS satellite collars in early February. The study will help biologists learn more about diseases in bighorns and provide important data on habitat use for future habitat enhancements.

Laramie - In 1976, Wyoming Game and Fish Department (WGFD) translocated 52 bighorn sheep from Whiskey Mountain to the Encampment River.  Two additional translocation efforts occurred in 1977 (17 bighorn sheep) and 1989 (19 bighorn sheep). Across the west, translocations of bighorn sheep have been integral in restoring the species to its historic habitats and ranges, establishing new populations in suitable but unoccupied habitat, and augmenting existing populations.
Following the translocation efforts, the Encampment River bighorn sheep population grew rapidly and peaked at approximately 150 individuals in 1982. The harsh winter of 1983-84 likely stimulated a population decline. Currently there are approximately 60 bighorn sheep in the herd. Bighorn sheep face a number of challenges including disease, predation, competition, habitat succession (i.e. open grassland/shrub steppe encroached by conifers) and human disturbances. Managers have struggled to identify the causes of the decline, or to isolate factors that continue to limit population growth in the Encampment River bighorn sheep herd.
This small population of bighorn sheep and the habitats they occupy are coveted by the public, landowners, and sportsmen. The Encampment River bighorn sheep often frequent the steep hillsides of the North Fork Encampment River, making them visible off of Highway 70 and often drawing the attention of the public. Harvest opportunities for rams have been offered in this herd unit every other year for the past decade in combination within the Douglas Creek herd unit. The Encampment River bighorn sheep herd has a reputation for producing great quality rams, making an opportunity to hunt within the herd unit highly desirable.
In 2018 the Encampment River bighorn sheep herd was scheduled to be sampled for diseases as part of the statewide bighorn sheep herd health surveillance study. In addition to the health surveillance work, wildlife biologists with the Wyoming Game and Fish Department hoped to use the fine-scale movement information collected from the GPS (Global Positioning System) collars to make inferences about habitat use. Five bighorn sheep ewes were captured, sampled for diseases, and collared. Unfortunately, the collars’ GPS capabilities malfunctioned.  
In 2019, three of those malfunctioning collars were replaced and three additional ewes were collared and disease sampled. Three of the collared bighorn sheep died in 2019. Two had been cached and were likely killed by mountain lions. One of these bighorn sheep had a sinus tumor, which was the first confirmed sinus tumor in the herd unit. By fall 2019, only two GPS collars remained on Encampment River bighorn sheep.  Although WGFD biologists were collecting movement data from the two collared bighorn sheep, biologists would need a larger sample of collared sheep to make any statistically valid assessments of habitat selection and movement patterns.
In February 2020, 10 bighorn sheep ewes were captured, disease sampled, and collared. The last two ewes with malfunctioning collars (from 2018) had their collars replaced. The collars will collect GPS location data every hour for three years and store the data on the collar. Real-time GPS location data will be collected every day and is transmitted via satellite every 5 days, which can be viewed on my computer. The collars are equipped with breakaway mechanisms that will release the collars from the ewes in November 2022. After the collar is released it will transmit its final location. I will then be able to retrieve the collar and download the animal’s hourly locations for the previous three years. If one of the collared bighorn sheep dies before the collar falls off, the collar will emit a mortality signal. At this point, biologists will go into the field, find the carcass, perform a field necropsy and collect important samples to submit to the WGFD veterinary lab.
The fine-scale movement data collected from the collars will help delineate annual variation in seasonal movements, habitat selection and resource use. Without understanding habitat selection patterns, it is difficult to plan and prioritize effective habitat enhancements to increase population resilience. These analyses will help us determine the habitat characteristics that bighorn sheep select under different environmental contexts and facilitate resource-use comparisons with other more productive herds.  In addition, our work will help inform the goals and placement of future habitat enhancement projects in the herd unit.
Some people have expressed concerns about the time of year this is done. Why is this the most opportune time to do such collaring and testing?
During bighorn sheep captures, all efforts are made to ensure the safety and survival of captured individuals. We carefully consider the timing of captures and try to complete bighorn sheep captures between December and mid-March. We want to avoid captures during the bighorn sheep breeding season (October-late November). We also want to avoid captures within two months of parturition (lambing), which happens mid-May for this herd. Bighorn sheep are very susceptible to overheating if captured when ambient temperatures are high, so we try to time these captures for months when temperatures are cool/cold.
The most common method to capture a large number of bighorn sheep is via helicopter net-gun. Capture operations using the net-gun method allow us to get a wider distribution of collars than is possible if we relied on ground captures. We used Native Range Capture Services to perform the net-gun capturing and slinging. This crew uses a helicopter to locate the sheep in their rugged and remote habitat. The pilot positions the helicopter close to the herd, and a net gunner shoots a 6-foot square net over one of the animals.  If a bighorn sheep shows signs of excessive exertion during the chase the crews will abort the chase. Once the bighorn sheep is in the net it is fitted with a blindfold and hobbled. It is then carefully lifted and delivered to a nearby staging area. At the staging area, WGFD biologists and veterinarians and volunteers collect disease samples and fit the bighorn sheep with a GPS collar and ear tags. The bighorn sheep are then moved away from the staging area and released.
Post-capture, biologists will be closely monitoring the collared individuals to see that they make it back to their capture locations.
The collaring can obviously tell the Wyoming Game and Fish about migration movements, but what is the importance of the tests performed on the animals?
Since 2012, the WGFD has been conducting statewide bighorn sheep herd health surveillance.  Through these disease surveillance efforts WGFD hopes to identify respiratory pathogens that are known to affect bighorn sheep populations, as well as other factors, such as trace minerals or nutrition, which may influence how one herd may do better than others when infected with the same pathogens.
Pathogen transmission can cause disease events and long-term lamb mortality. Following outbreaks, bighorn sheep survivors often carry the bacteria and transmit disease to lambs in subsequent years causing lamb death and poor lamb survival for years.
Once bighorn sheep are captured and flown to the staging area they undergo a series of tests: A tube of blood is drawn and will be used to determine whether the animal is getting enough minerals in its diet, and to serve as a serum bank for future disease investigations. Nasal and tonsil swabs are collected to determine if a sheep caries respiratory pathogens that can cause pneumonia. An ear swab looks for mites that can cause scabies, and a fecal sample can show the presence of lung and intestinal parasites. The temperature of the sheep is constantly monitored throughout the entire process to ensure the animals are not overheating or exhibiting too much stress.
What is the importance of the Encampment K-12 students helping with this project?
Teacher Jordan Seitz and Encampment students have been involved with the Encampment River bighorn sheep capture and collar efforts for the last three years.
We usually kick off the year with presentations about bighorn sheep ecology, history of bighorn sheep in Wyoming and Encampment, bighorn sheep habitat and digestion. Then we take to the field. We have done several field trips looking for collared bighorn sheep, learning about radio telemetry, and studying bighorn sheep habitat. These trips are the perfect time to cultivate a passion for the outdoors, wildlife, and conservation. The last two school years that I have been involved with the project the students have been absolute troopers. We have had them hike through blizzards, up steep hills, and down into rugged canyons in search of bighorn sheep and collars. Sometimes we find sheep during these trips and sometimes we don’t, but I think we gain an even greater appreciation for wildlife and their habitats when we actually experience it. “Experiencing” it in bighorn sheep country often means feeling the briskness of the wind, the burning in your calves and lungs as you walk in the terrain that wildlife easily navigates.  When I see the students, they will often report to me what sheep observations they have made on their own time experiencing the outdoors with their families, which is awesome.
Having students involved with handling the bighorn sheep during captures/collaring is an added bonus. There is something really special about being up close to these animals. I hope these experiences will encourage some of these students to pursue careers in wildlife management or at least recognize the importance of wildlife conservation.
Over the next few months I will be updating the students on bighorn sheep movements by sharing with them the location information we are receiving. We have even talked about students developing their own research question about the Encampment River bighorn sheep that we could look at answering with the collar/location information.

***The success of this project relied on the participation of local landowners willing to allow us to capture bighorn sheep on their property, as well as set up staging locations. Their cooperation is very much appreciated. Also, the collars for this project were purchased with Wyoming Wild Sheep Foundation Grant-In Aid funds, so many thanks to WY-WSF for their support.
 

- WGFD -


 
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