When I was in college, one of my favorite courses was animal behavior.  One of the more memorable lessons I learned was the difference between proximate and ultimate causes of behavior. Proximate and ultimate causes of events are important to distinguish.

For instance, say a researcher finds that sedimentation in streams is causing reproduction failure in trout. That is the proximate cause. Often the sedimentation is the result of logging roads—the ultimate causes.  But agencies and even far too many environmental groups do not want to identify the ultimate factors causing environmental degradation because naming names is politically risky.

Worse, they often fail to connect the dots. Land management agencies tend to want to treat the symptoms, rather than confront the ultimate causes of these environmental problems. The reason for this is easy to understand from a bureaucrat’s perspective—confronting the causes for environmental degradation usually involves directly confronting some economic interest that is financially benefiting from the activity.

Livestock production and its impact on other species is one of the best examples of how ultimate causes are ignored. When we look around the West and enumerate many of the factors causing environmental concern, knowledgeable folks can easily trace the cause directly back to livestock production. For example, when streams are dried up to support irrigated hay fields, and trout/salmon populations decline due to removal of water, the proximate reason is lack of water. However, if the dewatering is used to produce hay that is fed to cattle, than the ultimate cause of aquatic ecosystem degradation is livestock production.

We see these kinds of proximate and ultimate factors with many endangered species throughout the West.  Nowhere is this connection between livestock production and species decline more apparent than with sage grouse. Yet the United States Fish and Wildlife Service doesn’t even consider livestock production among the major factors in sage grouse decline.

This past week I attended the Desert Conference held in Bend, Oregon I saw yet another example of this blindness to livestock.

Among the representatives on a sage grouse discussion panel, there was a representative of the Oregon Fish and Game (ODFW). During her presentation, she commented upon the agency’s policies regarding sage grouse and she listed the threats that Oregon Department of Fish and Wildlife (ODFW) thought were a threat to the bird. ODFW identified factors like energy development, wildfire, invasive species (cheatgrass), vulnerability to predators, and climate change among the issues, nowhere was livestock grazing considered. When questioned about this seemingly inexplicable omission, she explained that ODFW thought livestock grazing benefited sage grouse.

The omission of livestock production as a major factor in sage grouse endangerment points out a serious flaw in the way agencies articulate and characterize the threats to wildlife.  What the ODFW biologist did was a common error, often seen when studying natural resources issues,  as well as in many other controversial topics. People often focus on the symptoms rather than the causes of observations.  In this case, nearly all of the threats to sage grouse with the exception of energy development are ultimately caused by livestock production—yet the ODFW did not want to discuss, much less, mention the cow factor.

Invasive plants like cheatgrass are a problem for sage grouse, in part, because the annual cheatgrass out completes native grasses which are better hiding cover for the grouse.  Cheatgrass is highly flammable and burns frequently. Due to the widespread occurrence of cheatgrass in the West, fire regimes have been altered, and we now see more frequent fires in many of our sagebrush steppe ecosystems. While the native species like sagebrush and bunchgrasses are adapted to occasional fires, they cannot survive fire year after year—a situation that often occurs when cheatgrass takes over.

Thus, as more and more cheatgrass dominates the West, there is less and less good sagebrush habitat.

But why is cheatgrass so prevalent in much of the West? The short answer is livestock. By trampling soil crusts which otherwise cover the bare spaces between native bunchgrasses, cattle often create perfect disturbed sites for cheatgrass seeds to colonize. More over cheatgrass seeds are carried from place to place on the fur of livestock, helping to ensure its widespread distribution.

Livestock also impacts sage grouse in other ways. For instance, wet meadows and riparian areas by streams are important foraging areas for sage grouse chicks during the first 3-4 weeks of life. They hunt insects in these areas and the usually dense vegetation provides cover from predators.  But cattle love grazing in riparian areas and wet meadows, eliminating the cover, and often due to ”down cutting” as a result of cattle trampling of stream bank vegetation, even eliminating the wet meadows entirely.

Another factor of sage grouse mortality is fence collisions. Sage grouse are slow fliers and tend to fly only a little above the ground.  As a result, they frequently run into barbed wire fences. The ODFW did not mention this as a problem, but a number of studies have shown that fences may be a major  mortality factor. So the proximate cause of this mortality is collisions with fences, but again one must ask why are the fences here? They facilitate livestock production.  So once again livestock is again the ultimate cause of sage grouse mortality.

Fences also impact sage grouse in yet another way. The fence posts make natural perches for birds of prey that often predate on sage grouse. So predation by a hawk or eagle maybe the proximate cause of mortality, but again livestock production is the ultimate cause of mortality.  Without the fences strewn across miles and miles of sage grouse habitat, birds of prey would not be a major issue.

Another cause of sage grouse mortality is West Nile Virus. In some sage grouse populations as much as 25% of the females have died from the disease. The virus is carried by mosquitoes. so while West Nile Virus is the proximate cause of sage grouse mortality, the presence of mosquitoes is greatly enhanced by livestock stock tanks where the mosquitoes find ideal breeding habitat. So again livestock production is the ultimate cause of sage grouse mortality.

Climate change is yet another factor. Changing climate is one of the factors which includes severe drought and extended warm season are driving the fire cycles that converting many millions of acres of sage brush habitat to annual grasslands of cheatgrass and other invasive species.  The reason climate is again yet another ultimate cause  has to do with cattle methane releases.  The bacteria in cattle rumen produce methane as a bi-product of digestion. These gases along with conversion of native vegetation to cow pastures are among the largest contributors to global warming. One World Watch paper estimates that as much as 50% of global GHG emissions may be due to livestock production.

Some opponents of sage grouse listing argue that coyotes are responsible for sage grouse decline. Never mind that coyotes and sage grouse have always co-existed, so one must ask what is the difference? The reason sage grouse are vulnerable to predators is the result of livestock removal of grasses that provide hiding cover.  The proximate of sage grouse poor recruitment is coyote predation, but the vulnerability is due to the ultimate cause—livestock production.

Indeed, when considering all the mortality factors and limitations that are driving sage grouse towards extinction, livestock production is easily the dominant factor. Curiously, it was not even mentioned as a concern by ODFW, and in fact, the ODFW official said livestock grazing was considered beneficial.  How can this be? The short answer appears to be that it’s politically convenient to enumerate the proximate causes rather than confront the ultimate causes for sage grouse decline. Ranchers continue to have a lot of political clout. It’s obvious that ODFW does not want to antagonize these lords of the sage.

This example of sage grouse decline and how livestock causes decline is a good lesson in proximate and ultimate causes. When you look closely at many different environmental issues in the West, one can generally trace it back to livestock production.


  1. DB Avatar

    And we are the ultimate cause of livestock production with our love of beef and tolerance for the “western way of life.” Pogo said it: “We have met the enemy and it is us.”

  2. Barb Rupers Avatar
    Barb Rupers

    Another excellent essay; thanks George Wuerthner.

  3. Ken Cole Avatar

    Another proximate cause for many of the recent fires we’ve seen this year is crested wheatgrass. Millions of acres have been seeded with this grass to pad the books for grazing. Some managers even tout it as “green strips” which supposedly burn slower. That claim is bogus and the wheat field like conditions in places like the northern Jarbidge are tinder boxes ready to burn by July.

    Again, the ultimate cause is livestock grazing.

    1. Ralph Maughan Avatar
      Ralph Maughan

      And perhaps the ultimate cause of the crested wheatgrass is the land grant universities years ago (but still) pushing the BLM and others to plant exotic grasses from other continents, which crested and Siberian wheatgrass are.

  4. Louise Kane Avatar

    Your writing always astounds me. a big problem with our state and federal agencies is that they do not indeed look for the long term solutions because defining the proximate cause of the problem, as you pointed out, would mean that doing so would require identification of an activity most likely tied to an economic or special interest. Fishing, grazing, livestock production, agriculture. And trying to regulate or require alternative, “greener” approaches is always met with huge resistance even when they are common sense, practical and not so expensive, especially so in the long run. Thanks for another excellent essay

  5. Linda Jo Hunter Avatar

    I am really glad I took time to read this . . Could you say that the extermination of the Wedge wolf pack in Washinton State was also the ultimate cause of cattle grazing on public lands? Maybe it was a more direct cause perhaps like a tantrum by one ranch.

  6. mikepost Avatar

    George, I dont dispute your premise but did not the first 50% of your listed “ultimate” causes also take place when large populations of native ungulates (elk, bison, deer) roamed the prairie before the cattle/sheep came?

    1. Bob Avatar

      No. There were also apex predators that kept things moving. Standing in one spot for more than a few moments created dinner service for a higher trophic level.

  7. Ken Cole Avatar

    Mikepost, elk, bison, and deer don’t use the landscapes in the same way the cattle and sheep do. Also, in many parts of the arid west, there weren’t any bison, or their numbers were so low that they weren’t ecologically significant.

    The range of sage grouse and bison had some but not a huge overlap. The best remaining habitat sage grouse tends to be in the sagebrush steppe that has higher precipitation and more grass. The lower elevation areas have been fundamentally changed through conversion to grasses like cheatgrass and crested wheatgrass which frequently burn keeping the sagebrush from recovering.

  8. smalltownID Avatar

    Don’t take this to the bank. George is inaccurate on many of his analyses and comprehension of the primary literature regarding sage grouse. Quickly, some inaccuracies, 1) “A number of studies” document fence collisions. Actually, one, and “frequent” collisions would not be used by Brian, the author of that research, or the co-authors. I have been shocked by how much money has been dumped into marking fences when we really don’t know how this ULTIMATELY affects mortality. We have no idea how many die from collisions so its premature to designate this as a serious threat – especially when this research really hasn’t been replicated outside Idaho. Although an easy target since we know why barbed fences are on the landscape right?

    2nd inaccuracy, coyotes, really? Maybe if you had mentioned ravens but there isn’t an abundance of research on depredation rates(nests or adults) by coyotes neither is it commonly discussed (if at all) among sage grouse scientists or at sage grouse professional meetings. Actually, I take that back, the lack of documentation of coyotes at sage grouse is considerable research that fails to provide evidence of coyotes influencing reproduction.

    Using ecological terms is fun but if it were really as simple as you claim – every proximate cause is a result of the ultimate cause of livestock grazing – then we wouldn’t be spending millions of dollars each year studying sage grouse still. Just because you can use an ecological term(s) most people are unfamiliar with doesn’t mean you can paint with such a broad brush.

George Wuerthner is an ecologist and writer who has published 38 books on various topics related to environmental and natural history. He has visited over 400 designated wilderness areas and over 200 national park units.

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George Wuerthner