Livestock threatened by toxic invasive species on rangeland

Preface.  Will cattle, sheep,goats, and horses have to be raised on feed lots in the future to prevent range land poisoning from invasive plants? Each year poisonous plants adversely affect 3-5% of the cattle, sheep, and horses that graze western range lands. There are many causes of livestock losses including (Global Rangelands 2020): 

  • Animals graze infested range lands when plants are most toxic.
  • Animals are driven, trailed through, or unloaded from trucks onto range land or pasture areas infested with poisonous plants.
  • Animals are not watered regularly or are allowed to become hungry, making them more likely to eat lethal quantities of poisonous plants.
  • Animals are allowed to graze in heavy stands of plants that are highly poisonous.
  • Animals are grazed on range lands early in the spring when there is no other vegetation except poisonous plants.

The USDA article below suggests livestock could be fed on feedlots to prevent them from eating toxic invasive plants on rangeland, but after oil decline, the energy to transport crops to feed lots is unlikely, and growing extra crops for livestock will be difficult without pesticides (see post “Chemical industrial farming is unsustainable”).

Rangeland and pastures comprise nearly half of the total land area of the United States. There are over 300 rangeland weeds in the U.S. that reduce carrying capacity and cost over $5 billion a year to control.  These species also reduce wildlife habitat and forage, deplete soil and water, the quality of meat, milk, wool, and hides, poison livestock, and reduce biodiversity (Mullin 2000, DiTomaso 2010).

In the U.S. invasive plants occupy 200,000 square miles of rangeland and are spreading at a rate of 14% a year.  Invasive plant-infested areas also experience far more wildfires at greater intensity and area burned (DiTomaso 2017).

More research needs to be done on this now while there is still time to do so, such as research on how and when to get animals to graze on yellow star thistle (Voth 2016).  Reduced livestock postcarbon may also reduce homo sapiens carrying capacity.

Alice Friedemann  author of “Life After Fossil Fuels: A Reality Check on Alternative Energy, 2021, Springer, “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer; Barriers to Making Algal Biofuels, and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Collapse Chronicles, Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report


USDA. 2011. Plants Poisonous to Livestock in the Western States. United States Department of Agriculture.

Poisonous plants are a major cause of economic loss to the livestock industry. Each year these plants adversely affect 3 to 5 percent of the cattle, sheep, goats, and horses that graze western ranges.

All too often the losses to individual livestock operations are large enough to threaten the viability of that ranch. Livestock losses can be heavy if animals:

  • graze ranges infested with poisonous plants when plants are most toxic.
  • are driven, trailed through, or unloaded from trucks onto range or pasture areas infested with poisonous plants. Animals are less selective in their grazing at these times of stress.
  • are not watered regularly.
  • are allowed to become hungry. Such animals are more likely to eat lethal quantities of poi- sonous plants.
  • are grazed on rangelands early in spring when there is no other green vegetation except poisonous plants.
  • are stressed, such as when they are trucked, penned, or handled (branding, vaccination, etc.).
  • are not limited on how much and how fast they consume the plants

Economic Impact of Poisonous Plants on Livestock Direct losses (effects on animals) include the following: • Deaths of livestock • Abortions • Birth defects • Weight loss (due to illness or decreased feed intake • Lengthened calving interval • Decreased fertility • Decreased immune response • Decreased function (due to damage to organs such as the nervous system, lungs, liver, etc. • Loss of breeding stock due to deaths, functional inefficiency, etc.

Indirect losses (management costs) include the following:
• Building and maintaining fences • Increased feed requirements • Increased medical treatments • Altered grazing programs • Decreased forage availability • Decreased land values • Opportunity costs • Lost time to management • Stress to management

Hundreds of plants are poisonous to livestock. Here are a few of the toxic plants or toxic plant categories in the West:

Bracken Fern (Western Bracken)
Colorado Rubberweed (Pingue)
Death Camas
False Hellebore (Veratrum)
Groundsel (Threadleaf and Riddell) and Houndstongue
Halogeton (invasive)
Hemp Dogbane
Nitrate-accumulating Plants
Poison Hemlock
Ponderosa Pine Needles
Rayless Goldenrod
Selenium-accumulating Plants

Snakeweed (Broom and Threadleaf)
Spring Parsley
St Johnswort
Sweet Clover
Tansy Ragwort
Water hemlock
Yellow Star Thistle and Russian Knapweed (invasive)
Yew Taxus

Other Poisonous Plants
Noxious Weeds

Leafy spurge, an unpalatable European plant invading Western rangelands,andUnpalatable Eurasian plants-spotted knapweed infests 7 million acres in nine states and two Canadian provinces

Foreign weeds spread on Bureau of Land Management lands at over 2,300 acres per day and on all Western public lands at twice that rate.

Increased wildfires

The spread of fire-adapted exotic plants that burn easily increases the frequency and severity of fires, to the detriment of property, human safety, and native flora and fauna. In 1991, in the hills overlooking Oakland and Berkeley, California, a 1,700-acre fire propagated by Eucalyptus trees planted early in this century destroyed 3,400 houses and killed 23 people [including my home — now there is a group fighting removal of eucalyptus because they’re “pretty”]

Meleuca invasion in Florida: sawgrass dominates large regions of Florida Conservation Area marshes, providing habitat for unique Everglades wildlife. Although sawgrass may be more than 9 feet tall, introduced Australian melaleuca trees are typically 70 feet tall and outcompete marsh plants for sunlight. As melaleuca trees invade and form dense monospecific stands, soil elevations increase because of undecomposed leaf litter that forms tree islands and inhibits normal water flow. Wildlife associated with sawgrass marshes declines. The frequency and intensity of fires change, as do other critical ecosystem processes. The spread of melaleuca and other invasive exotic plants in southern Florida could undermine the $1.5-billion effort to return the Everglades to a more natural state

In parts of the southern Appalachians, two related insects, the hemlock woolly adelgid and the balsam woolly adelgid, defoliate and kill dominant native trees over vast tracts.

Schmitz, DC. 9 July 1997. Biological Invasions: A Growing Threat. An army of invasive plant and animal species is overrunning the United States, causing incalculable economic and ecological costs. issues in science and technology. National Academy of Sciences.

A quarter of U.S. agricultural gross national product is lost to foreign plant invaders and the costs of controlling them. Exotic species have contributed to the decline of 42 percent of U.S. endangered and threatened species.

The chestnut blight fungus, which arrived in New York City in the late 19th century from Asia, spread in less than 50 years over 225 million acres of the eastern United States, destroying virtually every chestnut tree. Because chestnut had comprised a quarter or more of the canopy of tall trees in many forests, the effects on the entire ecosystem were staggering.

References & Recommended reading

DiTomaso JM, et al. 2010. Rangeland invasive plant management. University of Arizona.

DiTomaso JM, et al. 2017. Invasive plant species and novel rangeland systems. In: Briske D. (eds) Rangeland Systems. Springer Series on Environmental Management. Springer.

Global Rangelands. 2020. Poisonous plants on Rangelands.

McKnight BN ed. 1993. Biological Pollution. The Control and Impact of Invasive Exotic Species. Indianapolis. Ind.: Indiana Academy of Sciences.

Mullin BH, et al. 2000. Invasive plant species. Council for Agricultural Science and Technology Issue paper #13.

Sandlund OT, et al. 1996. Proceedings of the Norway/UN Conference on Alien Species. Trondheim, Norway: Directorate for Nature Management and Norwegian Institute for Nature Research.

U.S. Congress, Office of Technology Assessment. 1993. Harmful Non-Indigenous Species in the United States. Washington, D.C.

Voth K. 2016. Grazing reduces yellow starthistle.

Williamson, M. 1996. Biological Invasions. London: Chapman & Hall, 1996.

USDA. April 2011. Plants Poisonous to Livestock in the Western States. United States Department of Agriculture, Agricultural Research Service Agriculture Information Bulletin Number 415


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4 Responses to Livestock threatened by toxic invasive species on rangeland

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  2. Arthur Noll says:

    Goats look like part of the answer to this problem.

    • energyskeptic says:

      Arthur, except that goats cause even more erosion than sheep, both of them bad for the environment in that respect, though perhaps if managed better the harm could be lessened.

      • Arthur Noll says:

        It is definitely a matter of management. Goats properly managed don’t cause erosion, nor do sheep. The animal on the planet causing by far the most erosion is human beings with bad management of animals and cultivation of annuals. Grazing and browsing animals have been part of ecosystems lasting for many millions of years. If anything is suspicious as far as long term unsustainability due to erosion, it is is farming, not grazing-browsing animals. That is obviously management, given the long term sustainability seen in the fossil record of such animals. No such long term record exists for an animal killing perennial grass and trees to plant annuals, though.