Why Would Bison Have Done That??

I have an honest and earnest question:  What do we actually know about the movement and grazing patterns of historic bison herds in North America?

I’ve heard many similar versions of a story about the way in which historic bison herds moved across the North American prairie in pre-European days, but I’ve never been able to find someone who can substantiate it.  I’m not sure where the story (legend?) came from, but it seems to have become canon among many people in the grazing world.  It is particularly used by advocates of intensively managed grazing rotations, who say their grazing strategies mimic what bison did historically.

The most common variation of the story goes something like this: Back in the old days, bison herds were constantly on the move across the plains, grazing and stomping down the prairie as they went.  A bison herd would move into an area, stay briefly, and then move on – leaving behind short-cropped and trampled vegetation, which would get plenty of time to recover before another herd passed by.  The constant movement of bison was driven by humans, wolves, and other predators, who were constantly nipping around the edges of herds, picking off weak animals and keeping the herd moving.

I’m not saying the story is wrong, but I’m fairly skeptical.  Based on both observations and an impressive array of data from around the world, large grazing animals show a strong preference for recently burned and/or recently grazed vegetation.  The lush regrowth of grasses that have been recently burned or grazed is usually the easiest, tastiest, and most nutritious available, especially relative to undisturbed plants that are more mature.

This small area (a few hundred acres within a 12,000 acre pasture) of regrowth from a 2015 hay cutting became a predictable spot to find grazing bison during the remainder of that year and through 2016.  The animals visited the patch often, re-grazing many of the same plants over and over.  The Nature Conservancy’s Niobrara Valley Preserve.

In studies of patch-burn grazing, where cattle or bison are given access to both burned and unburned patches of vegetation, they graze spend something like 70% of their time grazing recently burned areas (and they stay on those areas most of the growing season), even when those burns make up a small percentage of the overall pasture.  The same pattern occurs in both small (a few hundred acres or less) and large pastures (10,000 acres or more).  These results are not coming from a few studies here and there; this is a large and comprehensive body of scientific research.  Bison and cattle are very good at optimizing their own diets, and when they are given the opportunity to regulate their own movements, without cross fences in the way, their optimal diet comes largely from recently burned and/or recently-grazed vegetation.

Given what we know about how bison and cattle (and many other large grazers) select their diets and grazing locations, how can that fit with the story I shared at the beginning of this post?  Why would bison have moved away from burned prairie into unburned/ungrazed grass that was more mature and less nutritious?  If they were forced to move from a particular place, why wouldn’t they have later circled back to graze the regrowth?  Many historic prairie burns, whether set by people or lightning, must have been of considerable size – probably plenty big to keep a herd of bison content for a full season, even if they were constantly bouncing around that burned area to stay ahead of predators.  No?  I just have a hard time imagining large areas of attractive, nutritious vegetation being sampled briefly by large herbivores and then abandoned and allowed to grow uninhibited for the remainder of the growing season.

I understand that much of our research on grazing patterns today is lacking the kind of predator pressure bison might have been under a few hundred years ago, and even a 10,000 acre pasture restricts the ability of bison to freely move across the landscape.  Given that, I’m open to the idea that movement patterns were different long ago than they are today.  Even so, I have a hard time imagining that bison wouldn’t have done everything they could to return to areas they knew contained high quality forage, even if they were being constantly pursued.  Can anyone provide some evidence to support that story?

In historic prairies, many patches of high-quality forage would have been transient (e.g., burned areas that were grazed for a season or so and then allowed to recover as bison switched to newer burns), but prairie dog towns might have represented a consistent supply of high-quality regrowth, and likely hosted fairly frequent visits from bison.

Even assuming (and I’m not) that bison herds were constantly on the move, never circling back to where they’d been earlier, it still seems unlikely that recently burned prairie would have been grazed for more than a few days and then just allowed to grow uninhibited for the remainder of the season.  Surely those burned areas (and later in the season, burned and previously grazed areas) would have been magnets for any other herd wandering nearby, and would have been grazed repeatedly (by a succession of nomadic herds) throughout the growing season?

Why does all of this matter?  In a way, it really doesn’t, other than for the sake of curiosity.  As I’ve discussed before, the way we design prairie management strategies should be based on today’s world, challenges, and objectives.  For example, it doesn’t make any sense to burn a prairie every three years just because we know that was the average historic fire frequency in that landscape.  The same is true with historic grazing patterns.  With increased levels of nitrogen deposition, woody plant encroachment, and habitat fragmentation, not to mention invasive species and climate change, today’s world is not the same as it was at whatever mystical point in history we might choose to try to replicate.  We have to manage today’s prairies in ways that make sense today.

Having said that, history does matter when it helps us understand how plant and animal species used to respond to the world around them, and what current adaptations and traits they have as a result.  That understanding can help us design and evaluate contemporary management strategies that fits with those adaptations.  It doesn’t mean we try to replicate history, it just means that we incorporate our understanding of it as we move forward.

Cattle seem to exhibit the same preferences for grass regrowth as bison.  These cattle are grazing in a burned patch in our Platte River Prairies this year.  That burned patch was grazed repeatedly and intensively all season while adjacent unburned areas were only lightly grazed.  The cattle were very selective, grazing mostly on their favorite grasses because of a moderate stocking rate.

If we’re going to incorporate a historic context into today’s strategies, however, we should make sure we’re as accurate as we can be about that history.  As I mentioned earlier, advocates of management-intensive grazing (and/or mob grazing, small cell grazing, and other similar strategies) mention the historic bison story often as a reason for managing cattle as they do today.  Because they contend that bison moved quickly across the historic landscape, never staying long in any one place, they propose that we manage cattle herds in that same way today.  I’m not saying those rapid rotation systems are right or wrong, I’m just wondering whether the historic context used to justify them is accurate.  I can’t understand why bison would have done what they’re supposed to have done, and would love to see evidence either way.

Even if bison were pushed off of areas they preferred, why wouldn’t they have returned later to take advantage of the nutritious forage?

I personally prefer the way prairies and wildlife respond to the kind of shifting mosaic approach we (mostly) employ on the sites I’m involved with, but that’s because I have a particular set of objectives, and I measure success based on those.  My personal guesses and extrapolations about how historic bison herds might have interacted with the landscape play a role in why I like our current approach, but they’re not really a major factor.  If I find out that historic bison acted very differently than I think they might have, I’ll appreciate that knowledge, but I’ll still evaluate our current strategies based on the objectives we have for today.  I will, though, pay closer attention to hints that species or natural communities might be showing stress due to exposure to conditions they’re not well adapted to.

Mostly, I’m just curious, and tired of listening to the same old story without knowing if it’s true.  Can anyone help me?

ADDENDUM:  Since writing this post a couple people directed me to this excellent article by Richard Hart that addresses my question fairly well.  Thanks to those of you who shared it!

60 thoughts on “Why Would Bison Have Done That??

  1. Chris, another excellent post! I believe there’s a tendency among some conservationists/environmentalists to think the goal of all conservation should be to return the land to a state as close as possible to what it was before European settlers arrived. But we’re never again going to have millions of acres of open prairie with million-strong herds of bison roaming those acres. I think you have it right that land management should be focused on meeting specific goals relating to environmental protection and sustainability, not on trying to recreate something long lost. But I’m also with you in wondering how the ecology of bison and the open plains actually worked.

    • That’s a group restoration ecologists doesn’t interact with much, but a good suggestion. Do you have any names or published works one could refer to, Tami?

  2. I don’t have any information about bison migration (I wonder if anyone really does) — but, of course, the Savory grazing method emanates from Africa, where largish grazing animals such as the wildebeest do definitely migrate. However, I believe that migration is totally weather-based — I’m sure there is lots of information on that particular migration. Whether or not bison did the same is a very interesting question. I don’t think they radio-collared, ear-tagged or leg-banded them in the 1800’s, so I don’t know how we’d ever truly know — but maybe one of your readers can help. I would think the last place that would have seen this pattern (if it existed) would be Alberta and Saskatchewan.

    Katie Stevens


  3. I’ve come across some thoughts on this. One is, a herd will eat favorite foods in a place, and move on when those are depleted. I have also heard of a ranch in California that grazes cattle with an eye to stewarding their land. What a concept!! They do not permit their herd to move at will, but rather hold them in place until they’ve eaten one patch fairly well. The thinking is this way the animals are not allowed to favor one or a few plants and then move on, which over time would alter the species balance of the vegetation.

  4. I wonder if there’s any evidence of learned migratory routes in bison as was found in mountain sheep. Then yes it would make sense that bison traditionally would have moved ahead leaving behind nutritous patches. The other question is how many other large herbivores shared the area ( i.e pronghorn or deer in such a way that is now found by sharing cattle and bison does not replicate the pre- colonial stage of prairie use by bison. Apart from wolves what other large predators were behind bison herds forcing them away from palatable patches?. What I’m trying to focus are about behavioral traits that could have over-ruled the mere nutritional sustainability patterns you describe. One other caveat are the historical descriptions that suposedly describe these massive movements. The observers were not 21 century trained scientists! Finally, although I live very far way from the N.Preserve, but have been involved in conservation management, what is evident is that the prairies have been fragmented and modified to such an extent that the management goals should be much less ambitious in terms of what could be accomplished in such a restricted portion of land. I’ve been following your posts for over a year now and simply just want to thank you for the good work you are up to: congrats!

  5. Hi!
    I worked at Kankakee Sands in Indiana last year, and they mentioned that the bison historically in that region regularly travelled hundreds of miles to a salt lick. So, to prevent their new herd from trying to leave, they provide salt and/or minerals.

  6. There is one piece of information you may be forgetting in your bison grazing scenario. Right now you have hundreds maybe thousands of head doing the grazing. the old bison herds counted in the millions. I’m sure the necessity to constantly be on the move was because there wasn’t regrowth on the prairie as fast as you would expect with a single small herd doing the grazing. Just a thought.

  7. How about searching for info from native Americans — they may have passed down oral histories from their traditions that could at least give you a hint.

  8. The best insight that comes to mind is elk browsing at Yellowstone. Prewolves they optimized their landscape foraging by browsing that which was best for them to eat. Add predators, and they move in ways that are more complex then simply what is the best place to eat.
    Caribou move constantly, providing a pulse of food for wolf packs they move through. For the rest of the year, the wolves need to live on voles, thereby limiting their growth of pack or general density in the landscape. Lower wolf density means less caribou loss.
    I think there are plenty of similar large grazer scenarios that fit the idea of moving regularly, but what we learned about bison movement in historical times during the great slaughter probably was different than what they did preslaughter.

  9. I’d guess that the biggest influence on the macro migrations of bison was seasonal movement. North to south, summer and winter. They were moving with the seasons to get to the best grazing.

  10. Another great post, Chris. I like htis moment of honesty: “Why does all of this matter? In a way, it really doesn’t, other than for the sake of curiosity.” Current goal for management of our micro-prairie remnants should consider, but not be constrained by history.

  11. The “news” about “Firehawks” in Australia makes me ponder. I’ve yet to find any reference to that behavior in North America. It may be that fire was more common than we think. Grazing herds sticking to burned areas and leaving unburned areas to mature, makes those areas more susceptible to fire. That preference by large herbivores also provides habitat for nesting birds, small mammals, and insects.

    What does burning do to the root systems of native grasses and forbs? How does it effect soil fungi? Soil animals? The depth of the prairie soil has always intrigued me. How do we recreate that?

    • I’ve seen swallowtail kites do this on Florida prairies being burned. Apparently they were once more numerous in the eastern plains up to Minnesota even. I even saw one this summer in the Loess Hills of Iowa. I speculate that historically they could have followed fires, but perhaps not intentionally spread them. But who knows?

    • Mara!! This is excellent! I can’t believe I’ve not seen this before, and couldn’t find it while searching. Thank you very much. I’ve just skimmed it, but it seems extremely relevant and helpful. I’ll dive into it more deeply with pleasure. Thanks.

    • Excellent. I met Hart through the Society for Range Management where he spoke on this very subject. Most memorable statement, “Sure the Great Plains were rotationally grazed, as one herd rotated off, another rotated on.”
      Thanks for posting this.

    • The Hart study describes bison as not possessing regular migratory routes, but rather being what I would call a fugitive species. The bison were always trying to stay ahead of Native Americans by disappearing once they had been located. Still, like migrating, their movement may have been along established trails that would create very severe disturbance in certain areas which is needed by some species.

      This study also mentioned that areas would not have been grazed by bison for many years due to various reasons like nearby human habitation or the local disappearance of herds due to drought or other factors. This lack of grazing would allow for recovery of those species that you have found always get grazed in a pasture despite whether or not they are in an area that had been burned. It would seem the rotation between fenced areas you have found to be necessary would be what is needed to replicate this dynamic and maintain what has been termed “ice cream” species.

    • But why would the migrate south because the would encounter more mature and less palatable vegetation? Not the same at all.

  12. I see no real contradiction between what you propose (shifting mosaic concept) and what you say that you doubt (3rd paragraph). Both of those ideas of bison movement are compatible and make good sense. Historic information exists about the movements of bison including the written accounts of George Catlin who lived with the Plains tribes for several years. He said “These animals are not migratory. They roam about and over vast tracts of country, from east to west and from west to east as often as from north to south”

    The author of the book “The Time of the Buffalo” Tom McHugh said ” Reliable eyewitnesses indicated that the majority of the herds, rather than moving north and south in uniform alternation, roamed their range capriciously,unpredictably, wandering with little regard for season, direction or climate”

    Certainly we know how fire influences forage quality and animal preference, and that was certainly one of the factors that affected their movement but perhaps not the primary factor.

    The “numberless” herds as they were described no doubt left the land grazed short due to the sheer number of grazers concentrated together. They were forced to move constantly just to obtain adequate forage. The short grazed / trmpled path of the herd most certainly must have been an effective fire break, altering the distribution of fire.

    Another factor not mentioned is that animals do not graze near their own manure. Once an area is fouled by dung, that species moves to a fresh area. The combination of predators, Indians, fire, forage supply, dunging, water, drought, and severe weather must all have been working together to influence how the bison moved. A shifting mosaic can occur at a very large scale.

    I see no problem whatsoever with the description of grazing patterns made in the 3rd paragraph, however, even at best, our grazing systems can only faintly mimic what we think the bison must have done.

    Plains Indians were nomadic and their movements were dictated by the presence of bison. If bison did not make large movements and vacate large areas for a long period, the Indians would not have had to be nomadic.

      • Steve Nelle makes some excellent points. I’d like to mention a couple of other things. In the article, Hart correctly points out that Native American communities put some limit on bison populations. However, from 1500-1700 the Native American population was reduced by 90% from exposure to European disease. This allowed the bison population to explode.

        My own Tribe was originally located in Mississippi. At the time of European contact, there were no bison in our country and hadn’t been since just after the Pleistocene. By 1700, bison had expanded all the way south and east into peninsular Florida as a result of diminished hunting pressure. Even during that period, bison herds were much rarer in our area than on the Plains, so their movements are easier to track, for what that’s worth. Our oral histories say that during severe droughts, specific herds moved over 100 miles from one river valley to the next. Written European accounts from the same place and time talk about bison herds and Native American hunters from outside the region passing through the area sporadically, so there must have been still longer “migrations”. Locally, these herds usually wintered in the river valleys, feasting on river cane (17% protein). They spent time on upland tallgrass prairie patches in the summer. Extrapolating these patterns to the time before the Native American population crash is obviously invalid, so is Hart’s attempt to do the same thing from even later data.

        The best indicators of the predominant grazing conditions on the Great Plains averaged over the last 10,000 years plus or minus, which I think is really your question, are the physiologies of the plants themselves. If the Plains resembled a heavily grazed pasture, with the occasional long resting period as Hart suggests, native prairies should thrive under those same conditions today.

        Obviously, they don’t. Here in southeast Oklahoma, the ranches are continuously grazed and are devoid of any of the palatable warm season perennials. We recently purchased such a place. After a year fallow period, we’ve begun putting our bison on an intensive rotational grazing pattern with a 90 day resting period. Now, formerly absent warm season perennials (big bluestem, little bluestem, Indian grass, and switch grass) are appearing from seeds in the ground that must be at least decades old. I have a friend who has been doing the same thing much longer. His land has sprouted up local native prairie plants as well as others that are today associated with distant prairie remnants on the Canadian and Mexican borders. Landscape restoration folks wondered where he got this diverse assortment of prairie seeds, but they were just in the soil waiting for the right grazing conditions. Obviously there was a tremendous amount of variability on the Great Pains in time and space, but the responses of these diverse plants seems to suggest that intensive rotational grazing with bison more closely approximates the predominant conditions that they evolved under than does the continuously grazed pasture.

        • Fascinating! Paying attention to ‘stories’ of our own histories is important and you have done that. The native american perspective which I (norwegian heritage from 1870s) don’t have and I also don’t hear often enough!

  13. Chris, if you get some good answers on this, do share! Also, you present a well-balanced approach to appreciating historical natural history while working within the realities of a changed (and ever-changing) present.

  14. Glad to see this post and comments. It has far more importance both in managing today’s prairie and in understanding and interacting with livestock graziers. First, both MiG and Mob graziers like to claim they are replicating natural herbivore grazing. Both are improvements over continuous grazing and set stocking (cg/ss) the latter results of which are what most people think of when grazing with livestock is mentioned. Both MiG and Mob will result in some improvement over cg/ss in plant diversity and soil coverage and health but they provide only limited improvement in grassland habitat for wildlife, undervalue the role and importance of periodic fire in a system that evolved with fire for thousands of years, and in fact the proponents of MiG and Mob claim that they replace the role of fire, and both are regularly abused. MiG and Mob probably occurred in some form from time to time but were not consistent in how bison interacted with the prairie anymore than fire at regular intervals or only certain seasons. I also believe in observations of bison by Yellowstone ranger Bob Jackson that historic bison herds were not large masses but large herds of internally segregated, maternally related groups, young bull groups, and old bull groups that to early travelers appeared to be one large mass. If we managed domestic livestock in a similar manner, we would probably see much different herd effect than we get from unrelated cows, steers or heifers all massed together. Even without, we come a lot closer to replicating the diversity and plant response under patch-burn grazing than under MiG or Mob, with Mob being the most similar to pbg in diversity and plant response due mainly to the much longer period of rest with Mob.
    Why should prairie managers care? Because, although prairies are composed of annual and long-lived plants and soil organism relationships but not even long-lived plants live forever. We must understand how to replicate the kind of disturbances that result in regeneration from seed as well as roots that just periodic burning without other factors such as variable herbivory can provide and how all affect associated organisms.

    • Chris,

      Great article.

      When I backpacked one October across Theodore Roosevelt National Park (an experience I highly recommend) I saw bison highly dispersed across the whole area (350 bison in 24,000+ acres at the time – herd was about to be culled). There were highly mobile pods containing around 30 mature females and young that were constantly on the move. Mature males were even more dispersed –they were all on their own or in groups of just a couple of animals. My understanding is that this is a typical pattern for much of the year and that the large aggregations of animals occur mainly during the rut in July and August. Is this a typical, natural pattern of bison dispersal? Is the notion of a giant concentration of bison being together year-round really a misnomer?

      • I’ll let others with deeper experience with bison answer your last questions definitively, but my strong impression/experience is that yes, bison spread out into smaller groups for much of the year. At the Niobrara Valley Preserve, for example, we might have 500 animals in a 12,000 acre pasture after calves are born, but I don’t think I’ve ever seen that many all in one place except during our roundups. We see them following pretty strong patterns in terms of how they use different parts of the pasture (especially focusing on recently burned areas, of course) but they don’t do that as one big massive group.

        • Very astute observation. The only larger gathering of nature’s herds is during the rut … and even this event pictures different groups of maybe 25-50 matriarchal s, 2 bulls (one 6-8 year old and one younger “hero’ worshiper male following 20-30 yds. behind his hero) chosen within this female group) all duplicated across ones view of that plain. Then there are the older bulls on that perimeter and then the teenanger bulls running from group to group… all in a high energy, but futile effort. Of course in any larger grouping of multiple families during this rut one sees one younger bull with one younger female .. maybe 200-300 yds. away from the main commotion. These are the elopers. The male can’t compete size wise with the big boys …so they go on a date. That female at any given time can run back to that comfort of family but chooses not to. Maybe a bit of indecision but not a lot.

      • Teddy Roosevelt has dysfunctional bison herds because of how they reduce that herd, but it is not near as dysfunctional as the Wind Cave herd (made up of crack whores and pimp bison). You won’t see the bull groups of 15-20 bulls at Teddy. and if those 30 or so matriarchal s only had the opportunity to have those necessary 2 males, the 5 and 4 yr. olds vital enough to keep up with that “always moving” then there might be enough to designate a somewhat functional ‘herd”. Of course, emotionally, all “herds” at Teddy are basket cases. Too many being ripped away from their families every fall. I say, compare to how slave families down South were bought and sold … put on the auction block … with one member ending up somewhere and another family member going to another plantation. and those left behind … to live in that shack …with all that empty feeling. This is Teddy for you.

  15. When European settlers came to the high plains and sand hills there were frequently large areas of bare sand dunes or as the settlers called them “blow outs.” I personally knew a family with a large ranch on the eastern edge of the sandhills that spent several generations revegetating some bare sand dunes. My interpretation has always been that the bare sand dunes were caused by overgrazing of burnt areas by free roaming bison herds for the very reasons that you mention.

  16. In the book 1493, a hypothesis is made about the huge bison herds seen when Europeans crossed the continent. It was supggested that the large herds were the result of a population boom that happened after the predator population crashed: European diseases crossed the continent ahead of settlers by several hundred years, giving ample time for the bison population to explode absent their top, human, predator. Historical reconstruction needs to consider all of the factors. It is a fascinating subject, indeed.

    • Glad you mentioned 1493. It and 1491 were mind openers for me, that further catapulted me into further reading. Also read Mari Sandoz The Buffalo Hunters. Heart wrenching because we know how it ends but gives an idea of how they went from region to region exterminating the species with no regard to life, bison or Indian.
      Also, Locust to learn about the migratory Rocky Mountain locust.

  17. In the book “1493,” a hypothesis was made about the huge bison herds seen when Europeans crossed the continent. It was suggested that the large herds were the result of a population boom that happened after the predator population crashed: European diseases crossed the continent ahead of settlers by several hundred years, giving ample time for the bison population to explode absent their top, human, predator. Historical reconstruction needs to consider all of the factors. It is a fascinating subject, indeed.

    • Every grazer species, just like Homo sapiens in his native element, has the ability to control its own numbers .. without that boom or bust. Predators are nice but not needed. Species HAVE to have that ability. And they do it by competition between the different extended families…. or “tribes”. It is war, but not in war in the modern sense. One “slowly” out competes another, pushing it out and down, over the generations. But the successful one does not just get bigger and bigger, but is limited in size by interactive recognition bonding. I know this is not in the biology books, but this is the way it is.

  18. Great insights from one and all. The more we know about the past, the better we can plan for the future of any given site. Even in the past the only constant was change. I assume that most of us manage for resilient natural communities, best as we can, emphasizing great diversity, apropos for our time and place. Maybe we would prefer to do without some elements of the past, such as the hordes of biting and stinging insects that early settlers encountered in our wetlands and prairies. Just wondering.

  19. Not all Plains Indians were nomadic, such as the Mandan. The Arikara were semi-nomadic. Some tribes may have used fire to bring the herds nearer to them by attracting them with the fresh re-growth vegetation.

  20. Has anyone studied wildebeest movement patterns on the Serengeti? It may be a different climate (i.e. wet and dry cycle), but it might offer insights into historic bison movements. Just a thought/suggestion.

  21. No one has mentioned flies. I am sure that God created flies to move bison. After a week or so, a large number would have hatched in any location to harass them.

    Mari Sandoz’s The Buffalo Hunters” is mentioned above. I seem to remember a map showing four large elliptical patterns representing herds of buffalo migrating which could be explained by moving into the prevailing wind away from the following flies. Moving away from flies would also contribute to dune formation because the buffalo would walk to the top of the dune ot be in the most breeze, just like we find cattle in a tromped out corner of a pasture on summer afternoons.

    Also, Mari Sandoz cites an estimated buffalo herd size that is about the same size as the number of cattle in the country today. And although the numbers estimated as slaughtered for tongues, hides, meat, etc are large, they are only a very small percentage of the number of cattle harvested. Hunting by white folk is not an adequate explanation for their near extinction.

      • No reference, but some context. Estimates used by Penn State and Mari Sandoz and others are that there were about 100 million bison. That is about the same as the total American cattle population. Weekly cattle slaughter last week was 571,000 head per the most recent USDA report or 28 million annually. That number has been almost constant for several years. It is sustainable. The human population in the areas where buffalo roamed (all the plains from Iowa &Minn west including the mountain states) was about 10 million in 1890. Annual meet consumption is about 100 pounds per capita. That would be about 1/2 a buffalo. Even that reports of wanton slaughter by the like of Lord Dunraven, or the accounts of Buffalo Bill killing a 30 a day do not suggest that the slaughter approached any thing greater than a small fraction of our current harvest.

        My hunch is that the bison population was already under pressure from nonpredator factors like venereal disease, parasites or respiratory problems to result in a stable population when hunted by natives and wolves. The pioneers probably introduced addition diseases that along with slaughter, sport and commerce hunting, and habitat conversion caused the bison population to collapse.

  22. Chris and everyone, great posts. Another possible factor is the differing expression of different classes of plants (even among grasses) under differing weather and precipitation patterns, resulting in bison seeking more palatable plants in differing areas. The bottom line in terms of today’s management however is that we should think in terms of managing for more than just grasses with the greatest forage production for livestock if the management goal is to benefit other uses and values.

  23. Certainly there are large animal migrations in Africa eg around northern Kenya and Tanzania along the Senrengeti Nat Park. So there are large animal migrations today, perhaps large animal herds migrate in great numbers because of a ‘herd affect’ just like Humans sometimes do things Because of the Herd, HAH! We are animals too!
    Lemmings even have seasonal migrations but you wonder if there are ‘triggers’ in very large herd migrations that might even be more behavioral. Met a fellow on the plane 5 yrs ago travelling the Gobi desert in all terrain vehicles and showed me an antelope ‘migration?’ herd that stopped his passage for an hour before he could restart! Birds Migrate but not all the groups at the same time nor the same destination. So there must be a ‘herd mentality’ like us Humans, (snicker), that plays a role and perhaps when the herd is not big enough it behaves differently. However even a small herd of cattle moves around a field together over a period of time.
    Good question you have here.

  24. Though we have lost the opportunity for eyewitness accounts, there is little doubt that the bison herds migrated with the seasons. Once the prairie grasses on the northern plains were covered with deep snow locating sufficient forage for large herds became quite difficult; and while bison do displace snow with side to side movements of their heads it is arduous grazing at best. And bison, like cattle, require increased feed in winter to maintain adequate body heat. Much easier to just move south ahead of the snow and cold. The southern plains would have been replete with forage as the herds had moved north to escape the heat of the southern summers, allowing the grasses to regrow and flourish. Keep in mind that before Europeans came the bison had very little competition for forage on the vast open plains. Deer, Elk, pronghorn antelope grazed as well but their numbers were dwarfed by the numbers of the bison. Indeed the biggest competitor for grass on the plains were the bison themselves by reason of their immense numbers. Of course not all the bison migrated. There were small bands who were able to locate shelter and enough forage to survive the winters, But survival of large herds of bison on the open prairies of the Dakotas, Wyoming, Montana and southern Canada during winter just isn’t feasible.
    Another indicator of bison herd migration is the oral history of the indigenous peoples who found reason for great celebrating and rejoicing upon the return of the herds as their very existence depended primarily on the bison.
    As stated in previous posts the reasons for the herd’s migration were many but the primary reason for a large herd movement is lack of forage. Whether due to fire, snow, or another herds grazing if there was nothing to eat the herd kept moving until sufficient food was found, And when it had been eaten they moved on. It boils down to ‘you gotta eat and I gotta eat and if there’s nothing to eat we gotta move’. And it is true that the herds were subject to hunting both by predators and Native peoples but there was never sufficient pressure from hunters in pre-European times to cause mass migrations due to that factor alone. Gray wolves were constant companions to the herds and they were a necessity in keeping the herd in good condition as they removed the old, weak and injured from the herd.
    If the bison had regular migration routes as suggested by some of the previous posts it may be that they moved along these routes because they knew where to find salt and other minerals necessary to their health in places along these trails. The bison were not stupid, if they were they would have died out long ago. They also used spots called wallows where they would roll in the earth for various reasons. Mostly it was for shedding winter hair but they seemed to use particular spots suggesting that these areas must have had something in the soil that made their skin feel good or killed parasites – or both. They would also roll in mud wallows to coat their hide with mud if they were being bothered unduly by flies.
    The bison, like most animals, had very good reasons for doing what they did; and though we may not know exactly what the reasons are it allowed to survive for thousands of years. And should man suddenly disappear from this country I have no doubt that, in a few generations, the bison would again flourish and cover the plains. They are survivors!

    • A few thoughts. There were no “large herds” of bison in the winter Pre Whiteman. They, like the Indian tribes, split into smaller groups for the winter. And the arrival of the large herds causing ‘rejoicing” was, I’d contend, Bison Mose’s leading their tribe through the wilderness. Those accounts were of later disrupted refuge camps on the move. To read further of those Indians…., the rejoicing was the arrival of old bulls. Thus being seen, in 2 weeks after all knew the mass would show.The cause of all these masses? Lack of all normal life of these bison. Think of all the isolated farm settlers in the New England states. Then Indian Wars .. and all settlers left their vulnerable homes for the towns and forts. Massing together for protection. As for wallows, most wallows along movement routes was for the same purpose as early mt. men blazing trees …to show those coming along behind where those in front were. In Yellowstone the bulls, 2 weeks ahead, would rub on a stump near the trail, wallow and snap 4-6″ saplings with their horns. But does every bull mean all follow? No. The cow-calf family following would have one of their family go over and sniff at each wallow or rubbed stump. What would be the need unless there were specific males needed to be followed? I saw this so many times in the fall, in the snow along those trails. Wallows here and there? There was no here and there. The perimeters of each families territory were marked by bulls ringing the matriarchal components. And wallowing in the herds? any number of reasons. Flies, dominant and sub dominance females (usually with urine) uptake of minerals through the skin (tis why fresh dirt was sought out), rolling in ash for parasite control … and finally, cause it all itches one time or another. The understanding and “expertise” is in picking out the types of wallow. One denoting boundaries is different than one where grazing takes place. I’d say any Native American hunter-gatherer knew a hell of a lot more than me.

    • I have had a few E Mail conversations with Savory in the last year. Allan talks of duplicating and mimicking nature, but all his “duplication”, whether in Africa or the USA or South America is with very dysfunctional animals. No male population, no extended families of grazers, all weaned, (except in Africa) and most all grazers segmented into stockers, “cow herd” etc. All grazers of the same ages, no males to eat coarse vegetation and no learning of broad leaf harvesting, from multi generational ancestors … means not at all mimicking of Africa’s wild game grazer populations. I would point this out to Allan … and his response and proof? all the young folk believe, believe, believe. Sounds like he is best at mimicking cult life… to me.

  25. An acquaintance let me know of this discussion. So … from my perspective.
    1) All grazers evolved with extended family order. To “raise” grazers without this social order means dysfunction at every level, grazing, disease fighting, genetic vitality, grassland restoration… and on and on. It also means those individuals and organizations trying to “help” bring back prairies …and those researching or managing for this supposed duplication of grazers ….Pre Whiteman … are on the wrong path. Without blood ties as focus (blood is a lot different than cohort association) it is all symptom science and management. All that is found is how one dysfunctional population of grazers compares with another dysfunctional grazer. Anyone who thinks herds are multiples of one …or think in terms of “herd density” … this means wild life biologists setting big game seasons, non profits who “reduce” herds based on only numbers of what they determine is the “proper” supposed duplication “natures” percentages of males, females and differing age groups … are all in the Dark Ages. All well intended, but none who have the foggiest of how actually reconstruct natural grazer systems. The good of these attempts is that it keeps ground from being plowed up and eroding. But reconstructing, no.
    2) All families have homes and all with homes have that specific area to defend (territories).
    3) Just as Omnivores can eat as a Carnivore instinctively, but need learning (think Grizzly bears) to eat from the plant community, Herbivores (grazers) eat grass as an instinctive survival food. But to eat (harvest) from native broad leave plants…. is a learned experience. I say harvest because compared to European agriculture’s top down eating Herb (Alfalfa-clover), “harvest” is selective picking of nutrient dense flowers, flower buds, seed heads, a whorl of leaves etc. To think a grazer learns all they need from trial and error is utopian thinking. I think of my old style (cows kept till 10-12 years old) cattle farmer bachelor brother neighbors. One fall day they told me “We see your buffalo eating all those locust pods. Once in awhile we see one of our old cows eating them”. Why so old and so few animals? Because all are weaned.
    4) There is no such thing as “matriarchal” when it comes to grazers (nor humans). At least not with my definition. The male groups located on the perimeters of each extended family are all part of the same family. All are needed by the matriarchal component for their support and other role needs. There are no “extra” bulls and no “non producing” old cows to “cull”. They all contribute to the welfare of that extended family. And all are needed to compete with other extended families. Yes, there is WAR between families of every grazer species. And this means between every families’ turf is No Man’s Land. And this No Man’s Land is so important in times of emergency. It is the “Soil Bank” or safety deposit box for each grazer species..
    5) The organization (and size) of grazer extended social order grazer extended families is limited to interactive recognition. IQ has nothing to do with it. Thus 300 in very favorable habitat (Plains and Mid West) to down to maybe 30-40 in the arid SW USA bison communities. It doesn’t matter if it is bison, elk, humans, chimpanzees, or ducks …or partridges in a pear tree…it is all around 300 max for blood ties. After this are associations …those recognitions of individuals crossing from one family to another, spanning territories ….. needed in times of competing emergencies, burn out, drought etc.
    6) This 300 magical number is divided into power groups and various spin off clans. On the matriarchal side, in fertile areas, maybe 50-60 max “matriarchal” power group and new spin off groups of 25-35 forming up. Those spin off matriarchal always have 2 males maybe 5 and 4 years of age with them year round. They have to have these young vigorous males because these vulnerable groups are its main protection … and any of the older main breeding males are too big to stay with spin off matriarchal components. It is the same for waterfowl and humans. Duck hunters always know those small flocks are easiest to deceive with decoys.
    7) The bull groups are segmented into very visible. .. and many 3-4 year olds, the lesser 6-8 yr. olds and then the even less smaller groups of 10-12 yr. old males. And then solitary or 2-3 in number of 15 year old ….and on up… ages of males. The younger male groups are the flankers on movements across their territory. The oldest bulls are in front and the 6-8 yr. olds are behind the female groups. It is a military movement.
    8) These male groups form the rings of protection for that extended families protection during static grazing (there are two types of grazing … movement across the landscape and static grazing (The teaching of young for Herb harvest happens during static. The younger male groups immediately near ….until the much older males guarding the very perimeters of that territory). If there is any movement from season to season (like from summer grazing on the Mirror plateau in Yellowstone to grazing on winter habitat on the Pelican Valley floor) then those big solitary bulls stay in winter graze areas to protect from encroachment from the much larger Hayden Valley bison herd.
    9) This ring of protection for bison …or wild cattle … is exactly the same for bison as it is in elk. Elk hunters complain the wolves of Yellowstone took a Northern herd from 18,000 down to 4,000…. An unnatural decline. But the N. herd all migrate out of the Park. Thus most all males are shot … leaving no rings of male groups to alert wolves coming in. But for comparison, the Park also has a 300 numbered elk herd in the delta area of Yellowstone lake. This herd doesn’t leave the Park. This means the 40% male population is still intact. That herd stays the same in number as before wolf introduction. Why, Why? Because each of those rings meant those individuals could discovery most every assault of wolf packs coming in for the matriarchal component. Years and years of glassing for poachers I saw those wolf packs coming in. I never saw those packs (YNP even had the one pack headquartering in this area the Delta Pack get past get past the ring of 6×6’s half mile away from matriarchal component)…. before those males somehow alerted those females and dependents. Off they ran to the woods. The ring of 7×8’s yes, half the time they got through. Too much distance, maybe a half mile between solitaries or a group of 2 or 3.
    10) I’d have to guess, with bison and wolves, those rings of turf protection, has more to do with protection against encroachment of other bison families. The accounts of fights between the bison herd bulls of one family on the move within a territory against other males of other families …well out of the rut season … is documented.
    11) Pertinent to grazing, it may seem Mob or MIG duplicates, but most all comparisons for its justification with very dysfunctional modern day cattle herds are with the moving bison refugee camps frontiers men saw. Those refuge herds of millions were like Moses and tribe wandering through the wilderness for 40 years without a home. Any grazer group under stress packs it up with other grazer groups for safety of that specie… albeit, with a lot of loss of efficiency for each individual family. Can one imagine what it was like to be in the back half of a million strong bison refugee camp movement trying to pick up any little bit of vegetation left from those front runners? Or what if a dysfunctional family group is overrun by the masses? Their home is eaten out. Nothing left but to join those masses. And with each group massing up with the larger group meant it was a exponential gathering mass of busted up homes and territories. But even these masses were composed of families within this mass. And when safety was reached each family spun off by itself for its own identity.
    12) Functional MIG in functional grazers means intensive grazing …close numbers of each family WANTING to be close with brothers, sisters, cousins and grandmothers moving across their territory. With the young, the yearlings and 2 year olds, in the immediate front. Leaders don’t “lead” unless it is needed. It takes energy to be in front. Thus those needing most nutrition, the growing ones, get to “creep feed”. The tight knit group eats what is in front, not spreading out and “eating the best and leaving the rest”. Thus one gets true tropic cascade effect …where all those behind this family, the eagles, hawks, coyotes, wolves (All those accounts of thousands of wolves ‘following’ meant not them predating bison (Wolves flank, not follow when hunting) meant tight knit bison families disturbed all those small mammals hiding in the vegetation …meaning easy pickings for those in the air or ground. The difference in mass movement of dysfunctional herds across large landscapes …and families with homes???? There was not the boom or bust for those species depending on that family of bison if that family had a well established territory … or home. The bison family was there 12 months a year, not once in a blue moon when that million head herd passed by. And as far as shit goes … what grazer wants to move through slurried poop trying to eat grass? And all that movement, all in place back and forth for MOB means shit gets slurried all over that vegetation. Take a lot at each gate opening. All the oldest or most aggressive cattle run to the other end of the paddock. This is because they can control movement through that graze by others. It isn’t because they are so happy, happy, happy. MIG would be like having to eat on a table where all the family shit on the same table as the food. Think of the stress this causes those cattle. In 30 years of back country patrol, where I lived in the back country 5 months a year, my horses never once took a dump in their corral. They always walked out of those open gates and into the woods, did their duty, then walked back in to stand under that fly free barn lean to. Unless the species is a pack rat, where urinating on its nest keeps predators at bay, species don’t like to be a part of their waste. And to think MOG grazing advocates can think this is how bison grazed in all those masses of dysfunction… where the last 500,000 bison had to pick through slurryed shit to eat??? Come on. It all makes no sense. At least those advocates could think of redesigning paddocks. Make them so there is continual moving forward in narrow, but long sections. Then give them resting places were none of that shit is all around.
    13)Having natures 40% male population meant those males ate the coarse vegetation. Then regrowth was there for the matriarchal component in that home territory. No need to brush cut to “knock those weeds down” or hay so cattle or bison had fresh growth. Females and males of all species eat differently. A big ole heavy steak for guys, yes? How can a Nature Conservancy think they get reenactment grazing by filling that prairie with stocker cattle? How can they think they can get anything remotely resembling natures grazing when all their grazers, whether bison or cattle, are merely a shell of that animal???
    14) Native American tribes, whether on horse or on foot, did most killing with surrounds, piskins or buffalo jumps .These were mostly the families of up to 100 matriarchal or the young bull groups of maybe 15-20. Those methods meant whole families of bison or elk were killed. Not the disruptive infrastructure loss by taking some of each family. To do as modern G&F hunting seasons impact would be like crippling the infrastructure of each of 3 towns (humans) as compared to destroying all of one and then having those 2 remaining well infra structured towns expand into the void of the lost town.
    15) Until the grazing community recognizes all grazers evolved, and needed, extended family social order to survive as a species all, as stated previously, is symptom research and management. Only after this recognition can adaptation be used to apply to all those dysfunctional cattle and bison herds in the world today.
    16) I suggest researchers study the wild Hereford cattle “herds” off Alaska to find answers …if they can’t “lower” themselves using “wild” grazer species as study basis. Of course what bison or elk herds on our public lands are functional? Basically none, except the Mirror Plateau bison herds or elk herd of the Yellowstone Delta? All those Nature Conservancy, Wildlife Refuge and National Parks herds are reduced based on the belief a herd is a multiple of one. Thus all family order in those herds is perpetuated with further dysfunction year after year.
    17) So in the end the question posed by the Prairie Ecologist will go on and on with symptom research and management…. and false answers …..as long as humans think we are superior to those other species on this earth.
    18) To study species with evolution’s answer means “we” will finally understand how a bison that doesn’t ever have offspring, still can contribute his genes to that family. And we will finally understand how disease fighting by any population is a lot more effective when undertaken by the entire family, than the genetic chance duplicated over and over by multiples of one.
    19) So much more but enough for now.

  26. Kind of an aside, but I put this blog post up on my Prairie Landscapes Facebook page and had someone reply with a comment about “woods bison”. Turns out the US supspecies (Bison bison bison) is about 75% smaller than the boreal one (Bison bison Athabasca). A comparison is in the link below, written when the herd was being re-introduced. Wonder if anyone has looked at this subspecies roaming patterns.

  27. Chris Helzer, thanks for this good post. It certainly stimulated many interesting comments. Evidence from La Brea tar pits strongly suggests seasonal occupation by pleistocene Bison antiquus, inferring a seasonal migration. Of course there was a broader suite of large herbivore species extant then, including now extinct mammoths, mastodons, camelids, horses, antelopes, etc. as well as extant pronghorn and deer. One wonders how the presence of now missing large mammals would have impacted patterns of seasonal distribution of bison on the plains.

    The historical records of bison include reports of mixed species, but of course far fewer species than during the ice age. There was some sort of historical association of bison with elk, antelope and reintroduced horses, but I doubt it would be easy to reconstruct details of those relationships now, given fragmentation. In east Africa, where there is a somewhat pleistocene suite of large animals (including elephants) the herds evidently migrate in the same season but according to slightly different schedules for different species. Smaller species are reported to take advantage of impacts of grazing by larger species to find more tender forage.

    As has been noted, weather patterns in Africa are different so it is difficult to say how relevant animal movement there is to discussions of N. American plains. Interesting that La Brea is located in Southern California which, like east Africa, does (and did) have a more clear rainy season. Fun to ponder all these complexities.

    • It takes energy to “migrate” any distance. And any migration needed means added dangers (predators, lost offspring, injuries etc.)Thus it is, any grazer that can do it all in place can establish better infrastructure than any other family “on the move”. And the better the infrastructure of that population the more competitive with other populations. But, of course any natural disaster can minimise this competitive edge. Early plains travelers became frustrated trying to follow bison trails. Most trails were intersected again and again, crossed over and over by different bison families going to where these travelers didn’t know where.Thus it is, hardy any “migration” of bison on those Plains …except for the trek by smaller numbered families to the specific river valleys each winter … and its high protein sedge ..and water.
      Yellowstone does have migrations … by elk. And the end of each of their migrations allows us a peek into families of all grazers moving between summer and winter homes. The mountains and all its drainages means it is easier to see how these “migrations” end … as compared to the Plains ….where geographic boundaries can not be easily discerned. The elk coming back into Yellowstone from Jackson Hole each Spring start as a “more or less” continuous line of animals. But as the trek goes on and on … a hundred miles …each family splits off to its particular drainage… to spend its summer. Some of these families go so far north into Yellowstone they cross the line of the Northern “herd” going South ..all to each of their specific summer homes. It must be quite the “Hi, good to see you again” as all try to stay on a foot wide path for miles and miles. It is quite impressive, especially the Northern herd going over the Mirror Plateau to Pelican Valley and points beyond. Any area of thick woods means “snow” 3 foot wide on each side of the trail. The “snow” is all the winter hair shedding off those thousands of elk. And this whiteness is there all summer long for one to see.
      Again, no migration on the Plains by bison, at least nothing of the like usually associated with MIGRATIONS. Movement, yes, but mostly because some human or environmental input that disrupted static infrastructure.

  28. Pingback: Choosing Your Destination Before You Choose Your Mode of Transport | The Prairie Ecologist

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