On my June road trip from southern Arizona to northern Nevada, I made a stop just southwest of Ely, Nevada. Ely is surrounded by interesting mountain ranges, such as the Egan, Schell Creek, and Snake Ranges, some of which I’ve written about in previous posts. On this trip I picked the White Pine Range to explore, and after stopping for gas in Ely, I headed for a campground labeled on the map as the White River Campground. I drove up a long dirt road along what I thought was the White River and eventually passed a US Forest Service sign that said camping limited to 14 days. But no campground. I continued on, and passed an encampment of students from UCSB and finally found a nice little hunters camp in a patch of pinyon pines, not too far from a meadow.
Fresh tracks and a large dung pile told me that I was in the territory of a band of wild horses. Wild horses are often called mustangs locally, but are actually feral horses. Some may have originated from horses left behind by the Spanish in the 1500-1600s, but most come from horses “dumped” by ranchers and other horse owners. They are common in the Great Basin; I’ve seen at least one band on nearly every trip I’ve made during the last few years. Almost nothing stirs the human spirit the way the sight of a horse running wild and free does. But they are also considered a scourge upon the land, causing damage to sensitive riparian areas, and ranchers complain that they eat grass that should be for their cows. With few predators, their numbers can increase rapidly; attempts by land managers to control their populations by rounding them up and adopting them out have been expensive and resulted in thousands of horses living out their lives in cramped holding pens. There is also a lot of debate about whether or not the wild horses can be considered “native” wildlife as, although horses evolved in North America, they became extinct about 10,000 years ago.
As part of another project, I’ve been reading a lot of papers on the paleobiology of the southwestern US. The biological prehistory of the Great Basin is especially interesting. As the glaciers retreated at the end of the Pleistocene, what is now the Great Basin was grazed by horses, camels, mammoths and mastodons, and helmeted musk-oxen, in addition to the deer, pronghorn, and bighorn sheep that still occupy the area. They were preyed upon by dire wolves, American lions, American cheetahs, and short-faced bears. Most of the large grazers and predators disappeared by 10,000 years ago, shortly after the first humans appeared in the area, although the role of humans in these animal extinctions is controversial. As the large grazers disappeared and the climate warmed, the shrub-steppe developed into the big sagebrush and shadscale habitats that occupy much of the area now. Without large grazers, different plant and soil communities arose – grasses intolerant of heavy grazing, and cryptobiotic soil crusts that are easily damaged by heavy animals.
Livestock appeared in large numbers in the mid-1800s, with hundreds of thousands of domestic sheep and cattle covering the range. Wild horses also increased during this time, and the impacts of almost half a million sheep, cattle, and horses in the Great Basin by 1900 had a permanent impact on the big sagebrush habitats, for the livestock brought with them cheatgrass.
Cheatgrass, from the old world, thrives in the soils disturbed by livestock. It provides valuable forage for grazers, but is also highly flammable. Fires race quickly through fields of cheatgrass, killing big sagebrush, shadscale, bitterbrush, and cliffrose; all important wildlife foods. Cheatgrass quickly reestablishes following fire, and limits the reestablishment of native shrubs. While this suits livestock, it is devastating to the wildlife that are dependent of the big sagebrush/shadscale habitats, including pygmy rabbits and sage grouse. Cheatgrass also increases the fire frequency in an area, from 60-110 years of native big sagebrush, to as little as 5 years in cheatgrass grasslands, further inhibiting reestablishment of native shrubs.
The ability of big sagebrush to tolerate grazing also depends upon moisture levels, slope, the timing and intensity of grazing and a variety of other factors. Most of the research on the relationship between big sagebrush and cheatgrass has been directed by range managers looking to improve foraging for cattle, in other words, trying to increase the amount of cheatgrass. A few studies have been done looking at the impacts of cattle and wild horses on big sagebrush. Almost all of the studies have found that grazing by large animals negatively effects big sagebrush, and presumably the animals dependent on it.
I don’t know if its possible to separate the impacts of wild horses from the impacts of cattle and sheep in the conversion of big sagebrush/shadscale habitats to cheatgrass grasslands. It may not be possible to restore big sage habitats once the conversion has taken place. Ranchers don’t want to give up grazing their cattle or sheep, and horse fans don’t want to remove wild horses. However, preserving native big sage/shadscale habitats by limiting disturbance such as grazing and mineral/oil development is critical to saving this rich and vital ecosystem.
Near my camp south of Ely, the big sagebrush looked pretty healthy, but the soils showed the hoof impacts of horses, cattle, deer and elk. Back in camp, I walked around a bit and enjoyed a nice sunset over the high peaks of the White Pine Range, cooked up some chili and headed for bed. It was a very quiet night, like many others I’ve spent in the middle of the Great Basin. No coyotes, only some distant Great Horned Owls and nighthawks I listened for the sound of horses hooves on sand, or alarm calls, or even the quiet sounds they make when talking to each other, but heard nothing. The dawn was greeted by a variety of sparrows, which started singing and chirping around 4:30 in the morning, joining the whooshes of nighthawks.
As I was packing up the car, I noticed Shadow sniffing intently in the spot where my tent had been. I went over to see what had him so captivated, and found a large, rather pissed-off scorpion. It didn’t move, didn’t try to strike at Shadow, even though he put his nose pretty close, and let me take some close-ups. It probably would have been at least 5 inches long if stretched out. But as I went back to packing, I was fervently hoping there wasn’t another scorpion packed up with my tent.
Beever, E.A., R.J. Tausch, and N.E. Thogmartin. 2008. Multi-scale responses of vegetation to removal of horse grazing from Great Basin (USA) mountain ranges. Plant Ecology 196:163-184.
Grayson D.K. 2006. The late Quaternary biogeographic histories of some Great Basin mammals (western USA). Quaternary Science Reviews 25: 2964-2991.
Knapp, P.A. 1996. Cheatgrass (Bromus tectorum L.) dominance in the Great Basin: history, persistence, and influences to human activities. Global Environmental Change 6: 37-52.
Mack, R.N. and J.N. Thompson. 1982. Evolution in steppe with few large, hooved mammals. American Naturalist 64:1-6.
Strand, E.K. and K.L. Launchbaugh. 2013. Livestock grazing effects on fuel loads for wildland fire in sagebrush dominated ecosystems. Great Basin Fire Science Delivery Report 2013. Available at: http://www.gbfiresci.org/storage/docs/syntheses/2013-04_DraftGrazingFuel.pdf.
Recorded with a PCM-M10 and Audio Technica AT2022 mic with Felmicamps pre-amp.
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