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The Weekly News Source for Wyoming's Ranchers, Farmers and AgriBusiness Community

Grazing Wyoming Rangelands

by Wyoming Livestock Roundup

The controversy over wild horses has again hit the news, and some of the recent developments could have impacts on Wyoming’s rangelands. Recently, the 10th Circuit Court of Appeals lifted the ban on horse slaughter plants in the United States. Of course this means after the final 10th Circuit ruling, it may be up to Congress to determine the next action. 

However, this ruling has definitely gotten the attention of horse advocates such as the American Wild Horse Preservation Campaign (AWHPC) and its parent organization, Return to Freedom (RTF). 

Interestingly, one of the requests made by the RTF and AWHPC is that the BLM stop “removing wild horses and burros from the wild and start managing them on the range with fertility control.” They also advocate sending wild horses “from holding facilities back to habitat areas that have been closed to wild horses and burro use over the past 40 years.” With this renewed interest in wild horses, it is pertinent to examine the potential impacts of horses on rangeland systems in Wyoming. 

Legal impacts

First, there are a few logistical considerations when dealing with wild horse and livestock grazing, including horses, cattle and sheep, on public lands. 

There are many areas in Wyoming that display a “checkerboard” pattern of ownership, meaning there is a mix of both private and public land laid out in a checkerboard fashion. Much of southwest and south central regions of Wyoming illustrate this pattern. 

This indeed raises the question of how wild horses, as a responsibility of the federal government and not of private landowners, can be managed within systems where it is difficult to separate public and private land that are intermixed and change from one section to the next. 


Along with logistical considerations, ecological issues are of utmost importance to the sustainability of Wyoming’s rangelands where many wild horses co-exist with cattle and sheep as well as antelope, elk and mule deer.  

Going back to historical records, it was the Spanish explorers and other European settlers that brought the horse back to North America, following their die-out after the last ice age that struck North America. Only a small handful of wild horses we see on western ranges today have lineage that can be traced back to stock brought over by Cortez and Coronado. 

The overwhelming majority are descendants of horses that escaped from their owners in the late 19th and 20th centuries. Many horses we see are not technically “wild” but “feral,” like an escaped house cat or other domesticated animal that has figured out ways to survive without human assistance (Crane et al., 1995). 

Range impacts

There has been much concern over the impacts feral horses have on western rangelands, due to horses’ aggressive and efficient grazing habits. 

Horses are able to eat various plants and their mouth allows them to crop forage practically down to the bare ground, if necessary. Our public lands are mandated for multiple use, so one obvious question is whether horses compete with other livestock and wildlife for forage? A horse’s habitat is quite variable, ranging from lowland and mountain sagebrush grasslands through boggy meadows to grasslands, stream bottoms and coniferous forest. 

A study conducted in 1992-93 found that feral horses in southcentral Wyoming preferred streamsides, bog/meadows and mountain sagebrush habitats while lowland sagebrush habitats were avoided relative to their availability. No apparent selection behavior was observed for grassland and coniferous forest habitats. 

Nutritional impacts

The study also indicated that a feral horse’s diet consists mostly of grasses and sedges with a significant amount of this forage being plants growing along streams. The issue increases in complexity as other animals are added into the system. 

Other studies have shown potential competition with other grazing animals, such as wildlife and livestock also preferring streamsides and mountain sagebrush habitats to other surrounding vegetation (Crane et al., 1997). Most dietary studies of elk suggest there would be considerable overlap with the primarily graminoid horse diet. 

A separate study suggests that the dietary overlap between horses and cattle during the summer averages 72 percent and in the winter increased to 84 percent (Krysl et al., 1984). 

Put into context, can our rangelands support the number of animals that currently inhabit them? Dietary preferences overlap highly, so whether or not there is enough forage available to horses, livestock and wildlife grazers is a carrying capacity issue. 

Although livestock occupy federal lands only portions of the year, occupancy of horses and wildlife species can be 12 months out of the year. This can mean a lot of AUMs harvested from our rangeland systems and a need for even greater consideration to the forage resource.

Proper management

Regardless of which animal species are being considered, we emphasize the need and importance of proper rangeland management. 

Whether Wyoming rangelands are supporting livestock, wildlife or horses, we, as land managers, are responsible for conducting, supporting and promoting good science with regards to protecting the ecological services that our rangelands provide. 

Services like forage for livestock, habitat for wildlife and water for all consumers are the very reason our rangelands are so important and vital to many individual’s livelihood and wellbeing. Rangeland health assessments and appropriate monitoring of user impacts are necessary for maintaining a thriving ecological balance and to better understand the multiple potential impacts when diverse groups of animals are present on the landscape.   

For more information, the following sources are available.

Crane, K., M. Smith, D. Reynolds. 1995. Horse Pasture. Wyoming Wildlife Publication of the Wyoming Game and Fish Commission. 59(3): 32-35.

Crane, K., M. Smith, D. Reynolds. 1997. Habitat selection patterns of feral horses in southcentral Wyoming. Journal of Range Management. 50(4): 374-380. 

Krysl, L., M. Hubbert, B. Sowell, G. Plumb, T. Jewett, M. Smith, J. Waggoner. 1984. Horses and cattle grazing in the Wyoming Red Desert, I. Food Habits and Dietary Overlap. Journal of Range Management. 37(1): 72-76.

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