Be in the Bison Know!

When most people think of the word 'savanna', they picture an African acacia savanna - something out of The Lion King or a nature documentary. Rolling, grassy landscapes dotted with occasional open-grown trees and teeming with charismatic wildlife. Well, we have savannas here in Minnesota as well! In lieu of acacias, North American savannas are a mix of prairie grasses and fire-resistant oak trees. Since European settlement, this ecosystem has been decimated by development, fire suppression and the removal of large herbivore grazers. In fact, oak savanna is considered Minnesota’s most threatened ecosystem. Scientists at Cedar Creek have been studying how to preserve, restore and maintain this unique mosaic environment since the 1960s. 

Past research 

Specifically, scientists onsite have been examining the role of fire on these landscapes. We’ve found that burning about 4 to 7 times per decade eliminates shrubs and non-savanna tree species and restores prairie grassland species, but that these frequent and intense fires also prevent oaks from regenerating. Our savanna research has partially restored the 2nd largest stand of oak savanna in Minnesota, but it is becoming clear that fire on its own leads to the slow conversion of the savanna into a grassland. When you walk along the public nature trail at Fish Lake, you can see this result with your own eyes – in the most “savanna-like” areas, there are very few small- and medium-sized oak trees: only mature adults.

Bringing Bison Back 

Why add bison to this long-running experiment? Bison may help support the regeneration of oak trees. Research elsewhere has shown the importance of bison in restoring prairies and grasslands, but their role in savanna restoration is unexplored. In grasslands, bison promote plant coexistence and diversity by preferentially eating the grasses that otherwise dominate the landscape. In this new experiment, which began in summer 2018, we hope to find out if this same preferential grazing will take place in the savanna. Grasses are the primary fuel for fires in the savanna, and compete with oak seedlings for light and resources. If bison preferentially eat these grasses, it could help young oaks in two ways – by reducing both the intensity of fires and the abundance of competitors. Our research has the potential to uncover an effective new strategy for restoring and maintaining a unique and vanishing Midwest ecosystem.

In 2018, we had an experimental herd of bison onsite, grazing from mid-June through mid-September in a 210 acre enclosure. With seven cameras inside the enclosure and an eighth just outside the fence looking in, there will be plenty of bison images showing up on Eyes on the Wild as our uploads progress! From the day they arrived, the bison were right at home in our savanna, and the cameras show them wallowing, exploring the enclosure, interacting, feeding and resting. Check out the gif below from the herd's first evening at Cedar Creek - all images that will shortly be up on the classification page!


This research also provide a chance for Minnesotans of all ages to look into the past, to a time when both bison and savannas were common across our state. If you find yourself in the area, we invite you to stop by our viewing gazebo on Saturdays to meet scientists, trained naturalists and other staff to learn about the research and view the bison! The savannas also provide excellent bird watching opportunities (including for the declining red-headed woodpecker) and a wonderful nature walk.

Fun bison facts:

  • Cedar Creek had 32 two-year old male bison in summer 2018, grazing in ~210 fenced acres of oak savanna. We don't know yet how many or which sex of bison we will have in 2019. Hosting a herd that is single-sex, single-age, and not fully adult minimizes the social pressures that might cause the bison to sustain injuries or try to escape their fenced area.
  • Our bison come to us each summer from NorthStar Bison just across the border in Wisconsin - a wonderful family-run commercial bison ranch that also loans bison to other conservancies and research/natural areas in Minnesota. 
  • The bison are the only animals at the reserve with ID tags. These tags are part of NorthStar's ranching operation rather than our research, but are an excellent clue to look for when classifying!
  • Our gazebo open hours, a handful of tours, and other associated programming reached >1500 people in 2018.


  • Bison are listed as “Near Threatened” on the 2017 IUCN Redlist. They are listed at “Regionally Extinct” in Minnesota – there are no wild herds in the state, although there are multiple herds managed by tribal groups, state parks, ranchers and conservation organizations.
  • Bison are grazers – they mostly eat grass, and after a summer of grazing, showed that they avoid the woody species in the savanna (including young oak trees!). Cedar Creek scientists spent much of the summer and fall sampling and measuring vegetation inside the enclosure, inside and outside grazing exclosures, and outside the whole area. Bison spend a whopping 9-11 hours a day foraging. A single adult bison needs about 24 lbs of food and 5-10 gallons of water a day!
  • Lots of grass in means lots of dung out - the average bison produces about 3 gallons of dung a day. This dung provides important nutrients for savanna plants, particularly in Cedar Creek's sandy soils, and supports a whole ecosystem unto itself. Scientists have found that a single bison dung pat can house as many as 300 different kinds of insects. Samples were collected at Cedar Creek during summer 2018 for diet analysis!
  • Bison are near-sighted and can’t see particularly well. However, they have excellent senses of hearing and smell! They are adept at sneaking up on people and are able to moving nearly silently despite their massive size, but humans can rarely sneak up on them.
  • Although adult male bison can weigh more than 2000 lbs, they are incredibly agile and athletic. Bison can run 40mph, jump 6 feet vertically, and turn on a dime. 
And in case you need more bison.... 
(because who doesn't?!), here's a quick video of them getting unloaded off the trucks last summer! When the camera pans to the right, look for the post with the little box on it in center screen - that's one of the Eyes on the Wild cameras! Then imagine my frustration watching this play out in real life with every. single. bison. going BEHIND the camera post rather than in front of it! :)

Like Eyes on the Wild, funding for the bison project is provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative‐Citizen Commission on Minnesota Resources (LCCMR). The Trust Fund is a permanent fund constitutionally established by the citizens of Minnesota to assist in the protection, conservation, preservation, and enhancement of the state’s air, water, land, fish, wildlife, and other natural resources. Currently 40% of net Minnesota State Lottery proceeds are dedicated to growing the Trust Fund and ensuring future benefits for Minnesota’s environment and natural resources.

All photos and video on this post were taken at the reserve by Cedar Creek staff and researchers and are used with permission.


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