---
title: "What the sources say about the American Bison | AnimalTracks.wiki"
description: "61 claims from the American Bison profile, each beside the words of the source that backs it."
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canonical: "https://animaltracks.wiki/animals/american-bison/sources/"
---

# What the sources say about the American Bison (*Bison bison*)

> 61 claims from the American Bison profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [American Bison](https://animaltracks.wiki/animals/american-bison/)

## American bison. Smithsonian's National Zoo and Conservation Biology Institute.

https://nationalzoo.si.edu/animals/american-bison

| The page says | The source says |
| :--- | :--- |
| North America's largest land animal | American bison are North America's largest terrestrial animals. |
| up to 2,400 pounds of it | Bison can weigh 1,800 to 2,400 pounds (816 to 1,088 kilograms). |
| Grasslands and prairie of North America | Originally, bison were found primarily in the grasslands and prairie of North America. |
| now in fragmented conservation herds across parts of Canada and the United States | Today, herds can be found in parts of Alberta ... in Canada, as well as Arizona ... in the United States. Modern conservation herds are substantially fragmented. |
| Mainly grasses year-round, plus flowering plants, lichens, and woody plant leaves when available | Bison are year round grazers. They feed primarily on grasses, but will also consume flowering plants, lichens and woody plant leaves depending upon availability. |
| A shaggy, heavily insulated head built to face straight into a blizzard and sweep snow off buried grass | The shaggy head is the most heavily insulated part of their body, which has adapted as such to withstand blizzards as the animal stands facing into the wind. ... To find grass in winter they sweep their heads from side to side to clear the snow. |
| backed by a 30 mph top speed | They can reach speeds of 30 miles per hour (48 kilometers per hour). |
| About 30 miles per hour (48 km/h) | They can reach speeds of 30 miles per hour (48 kilometers per hour). |
| Bison also have excellent hearing and smell but poor eyesight, so an entire herd can stampede if it is startled | They have an excellent sense of hearing and smell, but cannot see very well, so an entire herd can stampede if it is startled. |
| A bison's shaggy head is the most heavily insulated part of its body, adapted to withstand blizzards while the animal stands facing into the wind | The shaggy head is the most heavily insulated part of their body, which has adapted as such to withstand blizzards as the animal stands facing into the wind. |
| a bison also sweeps its head side to side to clear snow off the grass buried underneath | To find grass in winter they sweep their heads from side to side to clear the snow. |
| Bison are North America's largest terrestrial animals | American bison are North America's largest terrestrial animals. |
| A mature bull can reach 5.5 to 6.5 feet high at the shoulder hump and nine to 12.5 feet in length | bison are characterized by a hump over the front shoulders ... A mature bull can reach 5.5 to 6.5 feet (1.9 meters) high at the hump and nine to 12.5 feet (2.7 to 3.8 meters) in length. |
| cows run smaller, at about 5 feet high and 7 to 10 feet long | Females are normally smaller, at 7 to 10 feet in length (2.2 to 3.2 meters) and 5 feet high at the hump (1.5 meters). |
| Bison can weigh 1,800 to 2,400 pounds | Bison can weigh 1,800 to 2,400 pounds (816 to 1,088 kilograms). (note: ADW (2003) gives 318 to 900 kg (700 to 1,982 lb); the current Smithsonian page wins, and the page keeps its 'can weigh'.) |
| A bison can hit 30 miles per hour despite that bulk | They can reach speeds of 30 miles per hour (48 kilometers per hour). (note: ADW (2003) gives 62 km/h; the current Smithsonian page wins.) |
| its life expectancy is 15 to 20 years | The life expectancy of American bison is 15 to 20 years |
| Bison were once widespread from Alaska to northern Mexico | At one time, bison were widespread from Alaska to northern Mexico |
| Before 1800, bison roamed the Great Plains in vast numbers, with estimates ranging from 30 to 100 million | Before 1800, bison roamed the Great Plains in vast numbers; estimates range from 30 to 100 million. |
| By the 1890s, fewer than 1,000 were left on the continent | by the 1890s, there were fewer than 1,000 of these animals left on the continent. |
| The U.S. government slaughtered many bison in an organized effort to destroy the livelihood of the Plains Indians | The U.S. government slaughtered many bison in an organized effort to destroy the livelihood of Plains Indians. |
| Today around 30,000 bison live in conservation herds | conservation herds are comprised of around 30,000 individuals |
| which occupy about one percent of the original range | the current range occupied by conservation herds has diminished to one percent of its original status. |
| About 500,000 more are raised commercially as livestock | approximately 500,000 individuals are managed as livestock by private commercial ventures |
| a bison is mainly a grazer, eating mostly grasses but also flowering plants, lichens, and woody leaves when they're available | Bison are year round grazers. They feed primarily on grasses, but will also consume flowering plants, lichens and woody plant leaves depending upon availability. |
| working through about 1.6% of its own body weight in dry plant matter every day | On the average, bison ingest 1.6 percent of their body mass per day of dry vegetation. |
| A bison's shaggy head is the most heavily insulated part of its body, and it's built to face straight into a blizzard | The shaggy head is the most heavily insulated part of their body, which has adapted as such to withstand blizzards as the animal stands facing into the wind. |
| it sweeps its head side to side to clear snow off the grass buried underneath | To find grass in winter they sweep their heads from side to side to clear the snow. |
| After a few days, the calf can keep up with the herd | After a few days, the calf can keep up with the herd |
| Calves are nursed for seven to eight months and are fully weaned by the end of their first year | Calves are nursed for seven to eight months and are fully weaned by the end of the first year. |
| From Millions to Fewer Than a Thousand | by the 1890s, there were fewer than 1,000 of these animals left on the continent. |
| an animal of up to 2,400 pounds | Bison can weigh 1,800 to 2,400 pounds (816 to 1,088 kilograms). (note: vibe.reason; replaces 'unstoppable 2,000-pound prairie momentum', an unclaimed figure and a mood (#180)) |
| that can still hit 30 miles per hour | They can reach speeds of 30 miles per hour (48 kilometers per hour). (note: vibe.reason) |
| whose bulls prove their fitness by charging and butting heads | Male bison display their fitness by charging and butting heads with other bulls. (note: vibe.reason) |

## Aune, Jørgensen & Gates (2017). Bison bison. The IUCN Red List of Threatened Species 2017: e.T2815A123789863.

https://doi.org/10.2305/iucn.uk.2017-3.rlts.t2815a45156541.en

| The page says | The source says |
| :--- | :--- |
| Near Threatened | IUCN Red List category: Near Threatened (NT). |

## MacNulty et al. (2014). Influence of Group Size on the Success of Wolves Hunting Bison. PLoS ONE.

https://doi.org/10.1371/journal.pone.0112884

| The page says | The source says |
| :--- | :--- |
| a lone wolf that attacks an adult catches it only about once in 100 tries | the very low capture rate of a single hunter (1%; Fig. 2b) (note: 1% converted to once in 100. 'Capturing' is the attack-to-capture transition, so the denominator is attacks; a capture is biting and restraining, not a kill, hence 'catches'. The adult scope is its own claim.) |
| a lone wolf that attacks an adult | We limited our analyses of capturing to adult bison (note: Scope: the capture analysis, and so the 1% figure, covers adult bison only.) |
| Researchers studying Yellowstone's wolves describe bison as the most difficult prey for wolves to kill in North America | we use a unique dataset of observations of wolves hunting bison ... in Yellowstone National Park (YNP) ... Bison are the most difficult prey for wolves to kill in North America (note: The paper states this in its introduction, citing earlier work, so the page attributes it ('describe') rather than calling it the study's finding.) |
| three times more difficult to kill there than elk | in YNP they are 3 times more difficult to kill than elk |
| bigger, more aggressive, and more likely to injure or kill a wolf that attacks it | Bison are more difficult to kill than elk because they are larger, more aggressive, and more likely to injure or kill wolves that attack them |
| A lone wolf attacking an adult bison captures it only about 1% of the time | the very low capture rate of a single hunter (1%; Fig. 2b) |
| A lone wolf attacking an adult bison | We limited our analyses of capturing to adult bison (note: Scope: the capture analysis covers adult bison only (FAQ 2 and body).) |
| a bison that wolves bite and hold often escapes anyway | capturing was not necessarily killing because bison that were bit and physically restrained by wolves often escaped |
| Each extra wolf in the hunting group improves its odds of a capture, up to a group of about nine to thirteen | the threshold group size was 3–6 wolves for attacking and 9–13 wolves for capturing ... Beyond each threshold, groups size had no significant effect on success ... below these thresholds, each additional wolf improved group success by 67% ... and 40% (OR = 1.40±0.13, P <0.001) in attacking and capturing, respectively |
| Elk are the main year-round prey for Yellowstone's wolves | in YNP they are 3 times more difficult to kill than elk ... which are the main year-round prey for Yellowstone wolves |
| Researchers studying those wolves describe bison as the most difficult prey for wolves to kill in North America | we use a unique dataset of observations of wolves hunting bison ... in Yellowstone National Park (YNP) ... Bison are the most difficult prey for wolves to kill in North America |
| in Yellowstone they are three times harder to kill than elk | in YNP they are 3 times more difficult to kill than elk |
| a bison is larger, more aggressive, and more likely to injure or kill a wolf that attacks it | Bison are more difficult to kill than elk because they are larger, more aggressive, and more likely to injure or kill wolves that attack them |
| A lone wolf attacking an adult bison manages to bite and restrain it only about 1% of the time | the very low capture rate of a single hunter (1%; Fig. 2b) |
| manages to bite and restrain it | Capture Biting and restraining prey. (note: Table 1 ethogram: the study's definition of a capture.) |
| 93% less often than a lone wolf hunting elk | solo bison capture success (0.01) was 93% less than solo elk capture success (0.14 |
| A capture is not necessarily a kill, because bison that wolves bite and restrain often escape | capturing was not necessarily killing because bison that were bit and physically restrained by wolves often escaped |
| Each extra wolf in the hunting group raises its odds of a capture, up to about nine to thirteen wolves | the threshold group size was 3–6 wolves for attacking and 9–13 wolves for capturing ... below these thresholds, each additional wolf improved group success by 67% ... and 40% (OR = 1.40±0.13, P <0.001) in attacking and capturing, respectively |
| One Wolf, One Percent | the very low capture rate of a single hunter (1%; Fig. 2b) |

## Fuhlendorf et al. (2009). Pyric Herbivory: Rewilding Landscapes through the Recoupling of Fire and Grazing. Conservation Biology.

https://doi.org/10.1111/j.1523-1739.2008.01139.x

| The page says | The source says |
| :--- | :--- |
| Research at the Tallgrass Prairie Preserve in the southern Great Plains found that free-roaming bison and random fires interact across the landscape in a shifting pattern scientists call pyric herbivory, literally "grazing driven by fire," and that this interaction provides the foundation for biological diversity in North American grasslands | We call this spatiotemporal interaction pyric herbivory (literal interpretation means grazing driven by fire). Pyric herbivory is the spatial and temporal interaction of fire and grazing, where positive and negative feedbacks promote a shifting pattern of disturbance across the landscape. We present data we collected from the Tallgrass Prairie Preserve in the southern Great Plains of North America that demonstrates that the interaction between free-roaming bison (Bison bison) and random fires promotes heterogeneity and provides the foundation for biological diversity and ecosystem function of North American and African grasslands. |
| Fire and free-roaming bison interact across the landscape in a pattern researchers call pyric herbivory, literally "grazing driven by fire," and at the Tallgrass Prairie Preserve in the southern Great Plains that pattern was found to provide the foundation for biological diversity in North American grasslands | We call this spatiotemporal interaction pyric herbivory (literal interpretation means grazing driven by fire). Pyric herbivory is the spatial and temporal interaction of fire and grazing, where positive and negative feedbacks promote a shifting pattern of disturbance across the landscape. We present data we collected from the Tallgrass Prairie Preserve in the southern Great Plains of North America that demonstrates that the interaction between free-roaming bison (Bison bison) and random fires promotes heterogeneity and provides the foundation for biological diversity and ecosystem function of North American and African grasslands. |

## Bison Bellows: Birth of K-selected Species. National Park Service.

https://www.nps.gov/articles/bison-bellows-5-26-16.htm

| The page says | The source says |
| :--- | :--- |
| A newborn bison can stand and nurse within 30 minutes of being born, and within a couple of hours it begins to travel with the rest of the group | Within 30 minutes of birth, newborns can stand and nurse, and within a couple of hours, they will begin to travel with the rest of the group. |
| by which point a calf can weigh 350 to 425 pounds | By the time they are completely weaned of their mother's milk around 7 to 12 months, bison calves can weigh between 350 to 425 pounds (160-190 kg) |

## Safety. Yellowstone National Park, U.S. National Park Service, 2026.

https://www.nps.gov/yell/planyourvisit/safety.htm

| The page says | The source says |
| :--- | :--- |
| In Yellowstone, bison have injured more people than any other animal | Bison may appear tranquil, but these large animals have injured more people in Yellowstone than any other animal. (note: body; the sentence stats.dangerLevel: High rests on (injuries, none stated fatal, so High, not Deadly) (#180)) |
| The park tells visitors to stay at least 25 yards (23 meters) away | Keep at least 25 yards (23 meters) from bison at all times and never approach a bison to take a photo. (note: body; stats.dangerLevel) |
| a bison approached too closely may bluff-charge | If approached too closely, bison may respond by bluff charging (note: body; stats.dangerLevel ('Dangerous when cornered or provoked')) |