I have had several close encounters with bison while on vacations in Yellowstone and Grand Canyon National Parks and on Catalina Island. I’m glad to say that I maintained an appropriate distance and thoroughly enjoyed studying the creatures in their habitat. Researchers have also been studying these massive herbivores in recent years and their efforts indicate that increasing bison populations may help maintain ecosystem stability.

Bison are impressively huge and muscular animals. Adults can attain a height of 2 meters (6 feet, 7 inches), a length of 3.5 meters (11 feet, 6 inches), and a weight of 1,300 kilograms (2,870 pounds). They can easily flip over a full-sized pickup truck. Bison are the largest surviving terrestrial animals in North America.

Before the arrival of Europeans in North America, 50–60 million bison roamed from Mexico to Canada’s Northwest Territories, from Virginia and Pennsylvania to Oregon and Nevada. By the late nineteenth century, wholesale slaughter of bison had driven their population down to only a few hundred individuals. Thanks to conservation efforts, the bison population in North America now stands at half a million.

Bison Promote Biodiversity
Megafauna have a top-down effect on ecosystems. Field studies show that the largest herbivorous mammals are keystone species, meaning that they significantly enhance their ecosystem biodiversity.1 They do so by selectively foraging on palatable plants that dominate in the absence of big animal grazers, which provides room for other plant species to take hold and proliferate.2 With bison roaming long distances, their waste products distribute important nutrients to those parts of their environment that would otherwise remain nutrient-poor.3

Bison contribute to increasing biodiversity in a manner unique among megaherbivores. They engage in wallowing (see figure 1) to a degree not observed in other megaherbivores. The reasons for such extensive wallowing are not yet fully understood. Bison wallow more than what’s needed to control parasites affecting their fur and skin. Extensive wallowing by such large and powerful animals creates depressions that augment habitat diversity and form moisture-catch basins in what otherwise would be flat, dry prairie.


Figure 1: Bison (Low Center) Wallowing to Form a Depression
Credit: Hugh Ross

Long-term Bison Biodiversity Field Experiments
A field experiment published in 2005 compared the effects of bison and cattle grazing on tallgrass prairie compared to tallgrass prairie that was ungrazed.4 This study showed that plant diversity changed little during the 10 years the field observations were conducted. Both the bison- and cattle-grazed prairies exhibited increases in plant diversity, with the bison-grazed prairie showing a greater increase in plant species richness than the cattle-grazed prairie.

A team of eight ecologists led by Zak Ratajczak performed a follow-up field experiment with the goal of achieving quantitative, not just qualitative, outcomes.5 Therefore, instead of prairie enclosures of just 5 hectares (12 acres), they conducted field observations in prairie enclosures that were greater than 18 hectares (more than 45 acres). They also extended their field observations from 10 years to over 27 years. All of their tallgrass prairie enclosures were in the Flint Hills ecoregion of eastern Kansas (see figures 2 and 3).


Figure 2: Part of the Flint Hills Ecoregion
Credit: Edwin Olson, released into the public domain


Figure 3: Flint Hills Tallgrass Ecoregion Map
Credit: Cephas, Creative Commons Attribution

Ratajczak’s team noted that compared to ungrazed prairie, bison-grazed prairie showed a 103% increase in native plant species richness. Domesticated cattle-grazed prairie showed a 50% increase.

In the previous field study there was little change in climate. However, during the 27-year study conducted by Ratajczak and his colleagues, there was a two-year-long (2011–2012) severe drought, as severe as the Dust Bowl drought of the 1930s. In fact, 2012 was the most extreme dry year on record in the state of Kansas. Ratajczak’s team observed that long-term, year-round bison grazing resulted in plant communities that were remarkably resilient to the two-year severe drought. Such was not the case for cattle-grazed and ungrazed prairie.

Creation and Creation Care Implications
The ecologists concluded that “rewilding native megafauna could help to restore grassland biodiversity” worldwide.6 They also pointed out that large-scale reintroduction of bison throughout the American and Canadian prairies could greatly mitigate the economic threats from droughts and climate change.

This research affirms that bison were wisely created and designed by God to provide for and benefit North America’s plants, animals, and humans and to ensure that the continent remains full of the creatures God created. As the psalmist declares, “How countless are your works, Lord! In wisdom you made them all; the earth is full of your creatures.7

In Genesis 1 God gave a mandate to Adam and Eve and their descendants to manage Earth’s resources for the benefit of all Earth’s life. Ratajczak’s team’s research reminds us that part of that mandate is to continue to rebuild the population of bison and extend their habitat. That rebuilding and habitat extension has the added benefit of allowing many more humans to enjoy these magnificent animals and ponder the wisdom, power, and love of their Creator.

Check out more from Reasons to Believe @Reasons.org


  1. Allison Louthan et al., “Large Mammals Generate Both Top-Down Effects and Extended Trophic Cascades on Floral-Visitor Assemblages,” Journal of Tropical Ecology 35, no. 4 (July 2019): 185–198, doi:10.1017/S0266467419000142.
  2. Scott L. Collins et al., “Modulation of Diversity by Grazing and Mowing in Native Tallgrass Prairie,” Science 280, no. 5364 (May 1, 1998): 745–747, doi:10.1126/science.280.5364.745; Caroline A. E. Strömberg, “Evolution of Grasses and Grassland Ecosystems,” Annual Review of Earth and Planetary Sciences 39 (May 2011): 517–544, doi:10.1146/annurev-earth-040809-152402.
  3. David J. Augustine and Douglas A. Frank, “Effects of Migratory Grazers on Spatial Heterogeneity of Soil Nitrogen Properties in a Grassland Ecosystem,” Ecology 82, no. 11 (November 2001): 3149–3162, doi:10.1890/0012-9658(2001)082[3149:EOMGOS]2.0.CO;2. A free pdf of the entire paper is available at https://www.ars.usda.gov/ARSUserFiles/30180000/AugustinePDF/5.2001_Ecology.pdf.
  4. E. Gene Towne, David C. Hartnett, and Robert C. Cochran, “Vegetation Trends in Tallgrass Prairie from Bison and Cattle Grazing,” Ecological Applications 15, no. 5 (October 2005): 1550–1559, doi:10.1890/04-1958.
  5. Zak Ratajczak et al., “Reintroducing Bison Results in Long-Running and Resilient Increases in Grassland Diversity,” Proceedings of the National Academy of Sciences 119, no. 36 (August 29, 2022): id. e2210433119, doi:10.1073/pnas.2210433119.
  6. Ratajczak et al., “Reintroducing Bison,” page 1 of 7.
  7. Psalm 104:24.

About The Author

Dr. Hugh Ross

Reasons to Believe emerged from my passion to research, develop, and proclaim the most powerful new reasons to believe in Christ as Creator, Lord, and Savior and to use those new reasons to reach people for Christ. I also am eager to equip Christians to engage, rather than withdraw from or attack, educated non-Christians. One of the approaches I’ve developed, with the help of my RTB colleagues, is a biblical creation model that is testable, falsifiable, and predictive. I enjoy constructively integrating all 66 books of the Bible with all the science disciplines as a way to discover and apply deeper truths. 1 Peter 3:15–16 sets my ministry goal, "Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect, keeping a clear conscience." Hugh Ross launched his career at age seven when he went to the library to find out why stars are hot. Physics and astronomy captured his curiosity and never let go. At age seventeen he became the youngest person ever to serve as director of observations for Vancouver's Royal Astronomical Society. With the help of a provincial scholarship and a National Research Council (NRC) of Canada fellowship, he completed his undergraduate degree in physics (University of British Columbia) and graduate degrees in astronomy (University of Toronto). The NRC also sent him to the United States for postdoctoral studies. At Caltech he researched quasi-stellar objects, or "quasars," some of the most distant and ancient objects in the universe. Not all of Hugh's discoveries involved astrophysics. Prompted by curiosity, he studied the world’s religions and "holy books" and found only one book that proved scientifically and historically accurate: the Bible. Hugh started at religious "ground zero" and through scientific and historical reality-testing became convinced that the Bible is truly the Word of God! When he went on to describe for others his journey to faith in Jesus Christ, he was surprised to discover how many people believed or disbelieved without checking the evidence. Hugh's unshakable confidence that God's revelations in Scripture and nature do not, will not, and cannot contradict became his unique message. Wholeheartedly encouraged by family and friends, communicating that message as broadly and clearly as possible became his mission. Thus, in 1986, he founded science-faith think tank Reasons to Believe (RTB). He and his colleagues at RTB keep tabs on the frontiers of research to share with scientists and nonscientists alike the thrilling news of what's being discovered and how it connects with biblical theology. In this realm, he has written many books, including: The Fingerprint of God, The Creator and the Cosmos, Beyond the Cosmos, A Matter of Days, Creation as Science, Why the Universe Is the Way It Is, and More Than a Theory. Between writing books and articles, recording podcasts, and taking interviews, Hugh travels the world challenging students and faculty, churches and professional groups, to consider what they believe and why. He presents a persuasive case for Christianity without applying pressure. Because he treats people's questions and comments with respect, he is in great demand as a speaker and as a talk-radio and television guest. Having grown up amid the splendor of Canada's mountains, wildlife, and waterways, Hugh loves the outdoors. Hiking, trail running, and photography are among his favorite recreational pursuits - in addition to stargazing. Hugh lives in Southern California with his wife, Kathy, and two sons.

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