Whence the Buffalo Roamed

Integrated evidence based extent of occurrence for North American bison since 1500 CE and before .

Jeff M. Martin | Rachel A. Short | Glenn E. Plumb |Lauren Markewicz | Dirk H. Van Vuren | Bradly Wehus-Tow |Erik Ot’arola-Castillo | Matthew E. Hill Jr.

Buffalo Tracks– tracking the foundation herds. 

Whence the Buffalo Roamed: When and Where Were Bison Roaming During Colonial North America and Before?

By: Jeff M. Martin, Ph.D. Center of Excellence for Bison Studies, South Dakota State University


Our recent academic article, “Integrated evidence-based extent of occurrence for North American bison since 1500 CE and before” uses archival data to reassess the historical geographical range where bison once naturally roamed during or near the arrival of colonial explorers to this continent, and well before that, too (Martin et al., 2022).[1]

 Whence the Buffalo Roamed-=JM Figure 1d
Figure 1. Map of bison observations since 1500 AD (black points, n = 3,379) integrating three disciplines of historical ecology, archaeology, and paleontology to establish the historical extent of occurrence for bison (dark gray polygon with black border). Adapted from Martin et al. 2022.

(click on images to expand)

The data were compiled using extent of occurrence, a technique that identifies the geographic range of a species. It is found by pinpointing all of the known points of a species and then outlining them in a way that totally envelopes those known points with the fewest possible number of sides. (See the dark gray polygon with the black outline in Figure 1). Compiling a historical extent of occurrence in bison is important to ongoing restoration efforts because it shows that bison once lived and roamed over more geographical areas than previously thought. This indicates that 1) bison can potentially be reintroduced to more areas of the continent than previously thought, and 2) bison are adaptable to different ecosystems.


Armed with this information, potential reintroduction efforts can be prioritized depending on who owns the land, including private production, public wildlife conservation agencies, nonprofit NGOs, and tribal sectors. In fact, of the 6,400 observations in the article, approximately 3,400 observations firmly establishes that bison once spanned an impressive 59% of the North American continent since the year 1500 (about 500 years ago).


Although this number of bison probably didn’t occur at one moment in time, the data tells us that bison explored well outside of their typical habitat of prairie ecosystems found in the center of the continent, something much broader than previously depicted in other studies (thick gray outline in Figure 2).

Whence the Buffalo Roamed- JM Fig 2
Figure 2. Map comparing previous bounding edges of historic bison distribution by 1500 AD to 1950 AD (adapted from Martin et al. 2022) including previous works from Hornaday 1889 (thick gray outline; modified from Allen 1876), Sanderson et al. 2008 (thick red outline; modified from Hall and Kelson 1959), and Martin et al. 2022 (thick black outline; the focus of this summary). Blue dots are historical sites since the year 1500.


Figure 2 shows how understandings of historical bison distributions have changed over time. One of the famous historical bison distributions based on Joel A. Allen’s study (1877), later modified by William T. Hornaday (1889), is represented by the thick gray outline in Figure 2. This distribution omits historical sites since 1500 (represented by the blue points) that lie outside the thick gray outline in nearly all directions, especially in northern Canada and into Alaska, in the southeast along the Gulf of Mexico, and the desert southwest. 


The thick red outline in Figure 2 represents a more recent historical range distribution of bison which was presented in the book “Mammals of North America” by Hall and Kelson (1959), later modified by Sanderson and colleagues (2008). This distribution did a better job at including northwestern Canada and Alaska, the southeast, and the desert southwest. However, the blue points show that it still omits some data points in the Basin and Range region of the desert southwest in Nevada extreme northwestern Alaska, and mid-Atlantic of the Carolinas, and perhaps overextending into eastern Pennsylvania and eastern New York state.


A limitation of this new information, though, is that the data points are far more informative than the extent of occurrence (thick black outline in Figure 2). The extent of occurrence envelopes all the points using the fewest possible number of sides, thus including the Pacific coast as it connects the sites in northern Mexico to western Alaska. Even though sites are absent on the west coasts of both the U.S. and Canada, we lack sufficient evidence that bison were or were never there historically. 


This same logic applies to the arboreal forests of northern and eastern Canada. Coniferous forests notoriously have acidic soils that erode and deteriorate bone; therefore, skeletons do not become fossilized to later be discovered by excavation activities. Furthermore, these areas are wilderness, lacking major earth moving infrastructure activities that normally discover fossil and archaeological resources.

Whence the Buffalo Roamed- JM Fig 3
Figure 3. Map comparing bounding edges of previous studies on historical bison distribution by Hornaday 1889 (thick gray outline; modified from Allen 1876), Sanderson et al. 2008 (thick red outline; modified from Hall and Kelson 1959), and Martin et al. 2022 (thick black outline; the focus of this summary). Blue dots are historical sites since the year 1500 AD to 1900 AD, purple triangles are prehistoric sites prior to 1500 AD but after 10,000 years ago, and cyan squares are ancient sites prior to 10,000 years ago (adapted from Martin et al. 2022). The five orange arrows point to specific areas of interest where prehistoric and ancient bison distribution is far outside the “historical” distribution.


The extent of occurrence technique is useful in that, by design of its methodology (Grace et al., 2021; IUCN SSC Red List Technical Working Group, 2021), it creates a buffer to account for potentially unknown or lacking data. For example, if we instead include sites from the prehistoric era (purple triangles in Figure 3; sites occurring between 1500 AD and 10,000 years ago) and ancient era (light blue squares in Figure 3; sites occurring older than 10,000 years ago), then we see an even broader distribution of prehistoric and ancient bison extent on the continent (Figure 3). Note the five orange arrows indicating prehistoric bison sites well outside the “historical” ranges in: 1) El Salvador, 2) Belize, 3) southern Florida, 4) Orcas Island in western Washington state and Vancouver Island of British Columbia in Canada, and 5) Victoria Island of the Northwest Territories in Canada.


This dataset offers five take aways for researchers and bison managers: 1) a methodology for other species of concern to follow for their own assessments for historical and prehistorical distributions that integrate three disciplines of natural history; 2) the dataset allows future researchers to standardize their historical datasets for modeling past environmental change and animal response which allow for anticipatory management strategies under future environmental conditions; 3) this dataset creates a better understanding of the distribution of bison across several periods of time (i.e., millennial, century, decadal, annual, etc.) to better understand trends in reliance on hunting bison among the subsistence practices of prehistoric Indigenous peoples, 4) this dataset enables researchers to evaluate restoration status of bison into their native habitat, and 5) this new historical extent of occurrence illustrates where managers of the Bison Management System (private ranchers, NGOs, public agencies, and tribal entities (Martin et al., 2021)) could focus on bison reintroduction, at minimum, into their “historical” native range, if not even into their “prehistorical” and “ancient” ranges especially on the leading edges of changing climates favorable to bison. 


[1] The data collected for this article (which anyone can access online through FigShare; doi: 10.6084/m9.figshare.19314455) includes approximately 6,400 observations that span back to 200,000 years ago. We found this data by combing through archives from the disciplines of paleontology (fossils), archaeology (Indigenous and cultural use associated with bison remains), and historical ecology (first-hand exploration observations in journal entries).



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Hall, E. R., and K. R. Kelson. 1959. The mammals of North America. Ronald Press Company, New York City, New York.

Hornaday, W. T. 1889. The extermination of the American Bison. Government Printing Office, Washington, DC.

IUCN SSC Red List Technical Working Group. 2021. Mapping Standards and Data Quality for the IUCN Red Spatial Data. Available from: https://www.iucnredlist.org/resources/mappingstandards

Martin, J. M., R. A. Short, G. E. Plumb, L. Markewicz, D. H. Van Vuren, B. Wehus‐Tow, E. Otarola‐Castillo, and M. E. Hill. 2022. Integrated evidence‐based extent of occurrence for North American bison (Bison bison) since 1500 CE and before. Ecology. doi:10.1002/ecy.3864. Available from: https://onlinelibrary.wiley.com/doi/10.1002/ecy.3864

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