Another Grazing Myth Exposed
A review of the growing body of scientific research questioning the myth that the West's wildlife rely on livestock waters for their survival.
by Jeff Burgess
Previously published in the Arizona Riparian Council Newsletter, The Canyon Echo, and Arizona Wildlife News
A couple of years ago I accompanied some U.S. Forest Service staff on a horseback inspection of a livestock grazing allotment located in the eastern Superstition Mountains of Arizona's Tonto National Forest.
As we neared a muddy cattle tank, perched on a chaparral-covered hill, we scared off several mule deer that were taking a drink. The District Ranger turned in his saddle toward me and told me how he was glad livestock were allowed to graze public lands because deer would be scarce if there weren't any livestock waters. The theory that wildlife native to the West's arid ecosystems depend upon livestock waters for survival is a popular one.
It seems many federal land managers believe it. Almost every environmental assessment of a livestock management plan on working with nature I've read has warned that eliminating grazing could result in local wildlife populations suffering from the lack of livestock waters.
Most ranchers also seem to believe it and they frequently offer it in defense of livestock grazing on public lands. I've even had ranchers tell me there was hardly any wildlife in Arizona before ranchers arrived and "improved" the land, which is, of course, ridiculous. (Davis 1982)
The idea that wildlife depend upon livestock type waters is so prevalent there's a 1300 member conservation group of healthy people, called the Arizona Desert Bighorn Sheep Society, that works with the state's Game and Fish Department (AGFD) to try and increase sheep numbers by constructing permanent water holes in the Sonoran desert. Statewide, the AGFD maintains more than 725 water holes at an annual expense exceeding $200,000.
But considering how widely the theory is accepted, it's surprising how little scientific evidence there is to support it and how much there is that contradicts it. Even long-time proponents of these water developments are now questioning their effectiveness. (Brown 1997; Krausman 1997)
For instance, a recent review (Broyles 1995) of the bighorn sheep water development program AGFD has conducted in the Cabeza Prieta National Wildlife Refuge during the last 50 years concluded,
"It has not been shown that these developments are necessary, beneficial, or without harmful side effects."
Another study recently conducted in southern New Mexico (Burkett and Thompson 1994) compared wildlife populations at 20 sites that had man-made waters with the same number of similar sites lacking permanent surface water. They found that
"definitive effects of artificial water sources on native wildlife species were not detectable."
In other words, they didn't find more wildlife in the area with the man-made waters.
Another recent study on the health of the land conducted in western Arizona (Krausman and Etchberger 1995) looked at desert mule deer and bighorn sheep populations in the area of the Central Arizona Project canal before and after its construction. They found that,
"additional water was not important to the deer or sheep populations."
In addition to questioning their utility, there are studies suggesting livestock-type waters may even have negative effects upon native wildlife. For example, they can provide habitat for exotic fish and frogs that can get washed down in to streams during floods. (Sponholtz 1997) Introduced species are the major factor in the decline of native Western fish and amphibians. (Simms 1997)
The concentration of wildlife at artificial watering holes may also facilitate the spread of diseases. Some biologists worry they increase local predator populations by creating easy ambush opportunities. Another problem is they can allow cattle to abuse upland areas that were historically too dry for them to visit. (McAuliffe 1997)
Yet the idea that more water means more wildlife, like so many myths of the Old West, sounds good. It's an easy concept for hunters and hikers to believe because they know one of the best places to spot wildlife is around water holes. However, just because an animal stops to take a drink doesn't necessarily mean it's relying on that particular water for its survival.
But what about all of those biologists warning us the majority of the West's wildlife depend, in some way, upon riparian areas for their survival? Well, just because there's water doesn't mean there's riparian habitat. The fact is, few livestock waters support significant amounts of riparian habitat. Many of them are so trampled by cattle they are considered sacrifice zones.
Livestock Trough, Tonto National Forest, Arizona
Stock Tank, Coronado National Forest, Arizona
Livestock Pond, BLM Phoenix Area, Arizona
Besides, numerous studies have shown it's the amount and quality of suitable habitat that has the most influence on wildlife populations. For instance, as long ago as 1962 the AGFD completed research that showed Gambel's quail (Callipepla gambelli) don't need standing water, and that quail numbers in areas without it can be greater than those in adjacent areas with it. They discovered the quantity and quality of forage was the most important limiting factor on quail populations. In other words, you cant cram a square peg in a round hole and water is just one component of wildlife habitat and most Western wildlife species are adapted to its usual scarcity.
The tacit message from this new research is that just because something's good for cattle doesn't mean it's good for the land and the wildlife. (Heresy!) Any analysis of the impacts of livestock grazing on native wildlife populations should focus on grazing's net effects. And I doubt if there are very many situations on Western public lands where the marginal benefits to wildlife being provided by livestock waters are outweighing the degradation cattle are inflicting upon the area's entire wildlife habitat.