Bighorn Observation Volunteers Needed Colorado BHA

Project Lead:
SW Colorado BHA Regional Director
Dan Parkinson DVM                                   
[email protected]



Rocky Mountain Bighorn Sheep, the highly valued and iconic state animal of Colorado, are at risk of developing respiratory disease by pathogens acquired from domestic sheep grazing on public land. Effective separation of domestic sheep and goats from wild sheep is the only currently available management solution for preventing or minimizing disease transmission.  Our volunteer efforts will help the Forest Service and Colorado Parks and Wildlife gain more information about the presence of bighorns in and near active grazing allotments in the San Juan Mountains – especially in the Weminuche Wilderness.  

Here is a link to a beautiful and informative short video (about 4 mins.) produced by CPW about Colorado’s Bighorn Sheep.  Please take a moment to watch it.  


BHA spearheaded this project in 2017.  In 2018 BHA is partnering with Mountain Studies Institute to expand the scope of the project and the volunteer base. This project is open to all members of the public. 


During domestic sheep grazing season – Mid-June through Mid-October 2018. Choose any date that works for you, your friends and family – be it part of a camping vacation, a scouting trip or a special trip just for the challenge of finding bighorns!  


The bighorn observation program includes the landscape of all of the San Juan Mountains as shown on the maps below. Figures 1-3. 

Figure 1.  National Forests of Southwest Colorado and Weminuche Wilderness 


Figure 2.  Schematic map of Weminuche Wilderness and Area of Bighorn Project Interest 


Figure 3 Active Domestic Sheep Allotments in Relation to Bighorn Core Home Range in Weminuche Wilderness 


Researchers are particularly interested in looking for bighorns in and near three active domestic sheep grazing allotments in the Weminuche Wilderness. These allotments (Tank Creek, Virginia Gulch and Endlich Mesa) are in the area between the Animas River and Vallecito Creek south of Needle Creek/ Chicago Basin.  Major hiking trails of special interest in this area include the Endlich Mesa Trail, City Reservoir Trail, and the Upper Lime Mesa Trail.  

To look for bighorns near the active domestic sheep grazing allotments shown in Figure 3 please download and review the Grazing Allotment Maps and the Grazing Schedules listed below.  Each allotment will have a band of sheep (approx. 750 ewes and their lambs for a total of about 1500 plus sheep) and one herder.  The maps show the boundaries of the allotments and pasture and camp locations. The rotation schedules show the dates the pastures and camps will be in use during the 2018 grazing season.  


Grazing Allotment Maps and Corresponding Grazing Schedule 

A very helpful FS map of all the active allotments including grazing dates (from 2017) can be found here for general reference: 

Below is a new comprehensive map of active domestic sheep grazing allotments in Southwest Colorado in relation to bighorn core summer home range.  The area outlined in green is of particular interest now.


Be Prepared  

Prepare for an adventure in the wilderness. Some areas of the wilderness are accessible by day hikes or you may wish to spend a few days exploring an area and looking for bighorns. You will need good backpacking gear including rain gear, maps, GPS, binoculars and/or spotting scope and smart phone adapters (see section on adapters). The area is spectacular, wild and rugged. Be prepared for afternoon thunderstorms and some cold temperatures.  During fire season, be aware of the risks of accessing areas served by only one route and plan your escape route(s) accordingly. Avoid areas where you could be trapped by fire. Above all, be safe. 

Plan your hiking/backpacking and camping schedule according to your ability, desired destination and route. More information for the Weminuche Wilderness can be found here:


Tips for spotting and photographing bighorns 

Good optics are essential!  A good pair of binoculars for surveying a large area for sheep and a good spotting scope for close up viewing and photography can greatly increase the odds of seeing bighorns and enhance your overall experience.  Your smartphone can be attached to either your binoculars or spotting scope with a special adapter to allow you to take some important and beautiful close-up shots. BHA and Glassitup have arranged for a 40% discount on adapters used by volunteers on this project. Go to select the model you need for your phone and optics and enter bha40 to get the discount! 

Additional information on viewing bighorns can be found in the resource section below. 


How Do I Record Observations? Follow these 3 steps: 

  1. Report- If you see bighorn sheep near domestic sheep or in domestic sheep grazing allotments, IMMEDIATELY report your sighting to Brad Weinmeister, terrestrial biologist, Colorado Parks and Wildlife 970-375-6714. If you reach voicemail, leave a message with your location, date, time, and observation description. 
    1. Also call Columbine Ranger District 970-884-2512 and follow the same procedure.
    2. To report stray domestic sheep, call Jared Whitmer, USFS Rangeland Manager – Columbine Ranger District 970-799-1221
  2. Submit your observations to MSI using the iNaturalist App,, or a paper datasheet See detailed instructions at
  3. Email smart-phone photosand observation notes to [email protected]. This redundancy helps us verify your data validity and ensures that a back-up is stored.

Immediately reporting sightings can facilitate a more rapid confirmation and agency response.


Negative Findings:   

Even if you don’t observe bighorns it is important to report the date and general locations where you attempted to find them.  

  • To report that you didn’t see bighorns in the locations that you visited, simply send an email describing your observation route, an estimate of time spent looking for bighorns and a few of your digital photos (geolocation enabled) to [email protected].  For example, send a photo of the trailhead you started at, some points where you tried to locate bighorns along your route (preferably with identifiable landmarks) and where you ended your trip.  MSI will create a map of all observation points.  This information will help with coordination of this season’s volunteer efforts as well as give an overview of the project once completed in October.  


Positive Findings: 

  • Again, any sightings of bighorns near (within a mile or two) or in any active allotment should be reported immediately to the CPW and /or Forest Service as noted below.Reports should include the date, time, GPS coordinates, photos (with geolocation) or other accurate, verifiable location information. Time is of the essence! As soon as you have a cell signal, call, text or email the officials listed below and let them know this is high priority information!
  • If you use iNaturalist you can report that you positively observed and recorded bighorns in the locations that you visited. iNaturalist will create a map of positive bighorn sightings that will be monitored by MSI, BHA and the agencies.
  • Likewise, if you notice stray domestic sheepthat are clearly separated from their bands or that remain on the forest after the grazing season, please note their locations (take a photo) and report immediately to the officials noted below.
  • CPW and the Forest Service are also interested in reports of any pack goatsnear any bighorns or in bighorn core home range. Pack goats can also carry pathogens that can cause disease in bighorns.


In summary: You may want to take a photo of this with your smartphone

If you see:

  • bighorns in or near active grazing allotments when domestic sheep are permitted
    • Call Brad Weinmeister at 970-375-6714
    • Upload your digital photo(s) of bighorns to iNaturalist
    • Email [email protected] 
  • stray domestic sheep
    • Call Columbine Ranger District 970-884-2512 or Jared Whitmer at 970-799-1221
    • Upload your digital photos of domestic sheep toiNaturalist,
    • Email [email protected]
  • pack goats

Please know that timely, as soon as possible reporting is very important for effective response by agency personnel.  Agencies will need an accurate report from you including date, time, location (GPS coordinates preferred) of observation as well as other pertinent information such as proximity to domestic herds, if known. 

If you don’t see:

Please remember that even if you did not see any bighorns your observations are still needed.  After your trip, please report all your observations (locations that you looked for bighorns) and time spent in the field by simply sending an email describing your observation route along with your digital (geolocation enabled) photos to [email protected]


What happens with all the observations and data points?

MSI will compile all the observation information and produce a summary report to be given to CPW and the Forest Service at the end of October 2018.  BHA will provide a summary report to its members then too. 


What do I do if I encounter domestic sheep or livestock protection dogs while looking for bighorns? 

Our goal is to get our members and other interested individuals out in the wilderness for enjoyment and a chance to be of assistance to the Forest Service in gathering information about bighorn activity in or near active sheep allotments.  We are to act as observers only.  Please be respectful of the permitee’s livestock, livestock protection dogs and herders. 


  • Keep your distance and choose the least disruptive route around the flock.
  • Watch for livestock protection dogs near sheep (usually large, white or tan dogs).
  • Remain calm if a livestock protection dog approaches you. 
  • Verbally tell the dog “go back to the sheep” or say “no” in a firm voice. 
  • Keep your dog leashed. 

Do Not:

  • Chase or harass the sheep or the livestock protection dogs. 
  • Make quick, threatening movements toward the sheep or dogs. 
  • Try to outrun the livestock protection dogs. 
  • Attempt to befriend, pet or feed the dogs. 
  • Allow your dog to run towards or harass the sheep. 
  •  Mistake a livestock protection dog as lost and take it with you. 

Thank you for your help with this important program! 


Background on Weminuche Bighorns: 

At almost 500,000 acres, the Weminuche wilderness located northeast of Durango is Colorado’s largest wilderness.  Renowned for its rugged high peaks, pristine alpine lakes and wide-open expanses of tundra and mountain meadows it is home to headwaters of the Florida and Pine Rivers as well as Vallecito Creek. This wild public landscape is also home to iconic Rocky Mountain Bighorn Sheep. Weminuche bighorns are highly valued by sportsmen, wildlife watchers and scientists. The Weminuche population, including the Vallecito Creek Herd is classified as Tier 1 by Colorado Parks and Wildlife (CPW) because it is a true native population – a genetically distinct remnant of the once large, wide-spread herds of bighorns that lived in southwest Colorado.  This population is made up of three herds that are believed to be interconnected and now number, in total, only about 425 animals.  

Historically, bighorn sheep were once among the most abundant wild ungulates in the American West. Population estimates range from 1.5 to 2 million at the onset of the 19th century. Bighorn populations declined with westward expansion of human populations because of market hunting, introduction of domestic sheep and overgrazing of rangelands. 

Aggressive restoration and protection efforts have allowed populations to grow in the West from an estimated 25,000 in 1955 to 70,000 now. Yet in recent years, bighorn population growth has stagnated across the West despite continued restoration efforts.  Bighorn populations in Colorado reflect this trend, increasing from an estimated 2000 in 1955 to a peak of nearly 7500 in 2002 to approximately 6800 now.    

Current scientific consensus is that bighorn populations fail to thrive in large measure because of recurrent herd-level respiratory disease outbreaks associated with exposure to domestic sheep. According to a joint issue statement of The Wildlife Society and the American Association of Wildlife Veterinarians released in March 2015, “... it is now apparent that disease transmission from domestic sheep to wild sheep is a significant risk factor for the conservation and restoration of wild sheep populations,” and “effective separation of domestic sheep from wild sheep is the only currently available management solution for preventing or minimizing disease transmission.” 

Weminuche bighorns are listed by the Forest Service as a sensitive species, meaning there is concern for their long-term viability on the forest landscape. Whether due to disease from domestic sheep or other factors, the Vallecito Creek herd, which summers nearest the current active grazing allotments, has declined in number from 125 animals in 2000 to approximately 70 now.  Hunting opportunities have been reduced from three ram tags to one annually.   

Because the Vallecito Creek herd (S-28) is interconnected with the Cimaronna herd (S-16) and Sheep Mountain herds (S-15), an outbreak of respiratory disease in the Vallecito Creek herd could potentially spread to this greater meta-population resulting in the potential loss of all of the highly valued Tier 1 bighorns on the Weminuche landscape. 

Young bighorn rams and ewes often wander in historic home ranges in search of new grazing or breeding opportunities. Foray distances of a few miles to 20 plus miles have been recorded. Bighorns are naturally attracted to domestic sheep and may mingle with them resulting in a transfer of pathogens (spillover) that often causes acute respiratory disease in the affected bighorns.  Once infected, the foraying bighorns may die before they return to their home herd or they may bring disease to the herd.  Once the pathogens are introduced into the herd, the herd may suffer anything from a non-lethal pneumonia outbreak to a catastrophic all-age die-off.  Even subclinical infections of adults can cause respiratory disease in lambs that may negatively impact lamb survival for decades. As such, bighorns known to be exposed to domestic sheep are killed by CPW staff in a desperate effort to prevent further disease spread.  Durango Herald article (Nov. 30, 2016) 

In addition to foray activity by bighorns, separation is influenced by grazing practices that may result in some domestic sheep straying out of allotments and/or being left behind after the grazing season and potentially coming in contact with nearby bighorns.  In the Weminuche Wilderness and in many other public lands in the West there is a lack of current data documenting distribution of bighorns and foray activity in or near active domestic sheep grazing allotments.  There have been a few reported sightings (none verified and recorded by agencies) of bighorns in the active allotments in the Weminuche Wilderness. CO BHA hopes to help the Forest Service and CPW obtain more information about foraying bighorns, overall bighorn distribution and the presence of stray domestic sheep on the landscape by putting some BHA “boots on the ground” as bighorn observers.  

The Forest Service is responsible for managing bighorn habitat and livestock grazing on the Weminuche Landscape. Currently the Forest Service has delayed its final decision on the Weminuche Grazing Analysis pending further review of data being collected now. Six bighorns from the Vallecito Creek Herd (S-28) were captured in early 2017, fitted with GPS collars and released. Blood samples were also collected for disease screening. More bighorns will be captured, collared and tested in 2018/2019.  GPS data will help researchers note the movements of collared bighorns across the landscape.  A final decision will likely be made based in part on this new information and possibly from verifiable citizen science observations like this bighorn monitoring project. 

Verified sightings of foraying bighorns in or near active allotments, although perhaps unlikely because of the size of the landscape and the small number of bighorns in the area, will trigger necessary and required actions by the Forest Service, CPW and the permittee. CO BHA thanks all volunteers in this endeavor and thanks the Forest Service and CPW for the opportunity to be of service. 

Weminuche Wilderness information 

Living with livestock protection dogs 

Bighorn biology and viewing tips 

Current References for Bighorn Sheep Pneumonia 

The Wildlife Society and American Association of Wildlife Veterinarians Joint Issue Statement, Domestic Sheep and Goats Disease Transmission Risk to Wild Sheep.  March, 2106  

The Wildlife Society Fact Sheet, Impacts of Disease on Bighorn Sheep Management.  February, 2014. 

Bighorn respiratory disease 

The following very current and important articles and related articles can be found at 

Cassirer, F., Manlove, K., Almberg E., Kamath P., Cox M., Wolff P., Roug, A., Shannon J.; Robinson R., Harris R., Plowright R.K., Hudson P., Cross P., Dobson A., Besser T. 2017. Management of pneumonia in bighorn sheep: risk, reservoirs, and resilience. Journal of Wildlife Management. doi:10.1002/jwmg.21309 

Plowright, R. K., Manlove, K. R., Besser, T. E., Páez, D. J., Andrews, K. R., Matthews, P. E., Waits, L. P., Hudson, P. J. and Cassirer, E. F. (2017), Age-specific infectious period shapes dynamics of pneumonia in bighorn sheep. Ecology Letters. doi:10.1111/ele.12829 

Frances Cassirer, Kezia R. Manlove, Raina K. Plowright, Thomas E. Besser. Evidence for strain-specific immunity to pneumonia in bighorn sheep. 2016. Journal of Wildlife Management. doi:10.1002/jwmg.21172.


About Dan Parkinson

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