By Angie Burke
Volunteer Coordinator, The Nature Conservancy
We are all familiar with the saying “It’s the little things that matter”, and it’s the management of the tallgrass prairies at Nachusa Grasslands that has made a big difference for the littlest of things— mammals. Our paper “Early Small Mammal Responses to Bison Reintroduction and Prescribed Fire in Restored Tallgrass Prairies”, coauthored with Dr. Holly Jones and Dr. Nick Barber, sheds light on how the varying management of prescribed fire, coupled with the reintroduction of grazing bison, has created a habitat haven for the small mammals in a mix of agriculture and rural development.
blocking our safe access to a site, to capturing meadow jumping mice awakening from their winter slumber, every sampling season held a new adventure for us.
Some of the little buddies we captured and released were deer mice, white-footed mice, prairie voles, northern short tailed shrew, meadow jumping mice, harvest mice, and my favorite, the 13-lined ground squirrel. Rain, snow, or shine, the little buddies are welcomed to the study each season with excitement by the many stewards, volunteers, and scientists that call Nachusa home.
In the first two years since bison were reintroduced, we found fewer small mammals in older sites relative to new restorations and fewer as time since fire increased. Additionally, there was a higher diversity of what we did document in those older sites and slightly lower diversity (fewer than one species, on average) in sites where bison were present. This difference was driven mainly by prairie voles; fire removes litter and residual dead vegetation which is important habitat for voles. The overall abundance was especially influenced by the deer mice, which are able to use the areas with a higher prevalence of bare ground associated with frequent/recent fire on the landscape.
Overall we found that bison reintroduction had fairly weak impacts to small mammal communities in the first few years. Bison, when reintroduced at a relatively low stocking rate, are not likely to cause significant shifts to this community or, by extension, to the seed predation and dispersal functions they serve in prairies. The many different types of habitat created by the managers at Nachusa varying prescribed fire with grazing bison maintain the diversity of small mammals on the landscape scale. Continuing to document the changes in the small mammals through time, while capturing the changes with other animal, invertebrate, and plant composition, will help to show how the little things matter on a big scale when it comes to tallgrass prairie restoration.
By Jason Willand, PhD
I first visited Nachusa Grasslands in August 2008 while I was working for the Illinois Natural History Survey. I was overwhelmed by the sheer scale of the restorations that comprised the preserve and never envisioned myself conducting research on these restored prairies. As fate would have it, I returned to school in 2009 to start work on my doctorate degree and was able to fit part of my research into the restorations at Nachusa. The research was for the first chapter of my dissertation, where I examined the role of seed and bud banks for plant community regeneration during prairie restoration. The field portion of this work lasted only five days, and afterwards I was hoping that I would have a chance to return to conduct more research. As fate would have it again, I was able to conduct a small research project at Nachusa as I was wrapping up my dissertation in July 2014.
The research project was the result of brainstorming between my dissertation advisor Sara Baer and myself. With the imminent introduction of bison on the preserve in October 2014, we wanted to develop a potential long-term monitoring project. We decided that an interesting study would be to examine the resource availability of the remnant and restored prairies before the bison were introduced. Bison were the dominant grazers in the tallgrass prairie ecosystem before settlement by the pioneers. They play a “keystone” role in the maintenance and diversity of prairies because of their wallowing behavior and preferential grazing on graminoids (grasses and sedges). Most bison research to date has been conducted either on private game ranches or remnant prairies, with little research coming from restored prairies.
We collected data on three resources that could affect where bison would graze in the introduction area: plant biomass, the forage quality of the biomass, and soil carbon and nitrogen. Knowledge of plant biomass provides a rough estimate of the amount of plant matter available for bison consumption. Forage quality of plant biomass is informative because it not only tells us how much of the plant matter is actually digestible to the bison, but also the fat and crude protein content of the plant matter. Soil carbon and nitrogen are vital because as a plant uptakes them, they allow a plant to produce important macromolecules for growth, such as proteins.
In order to adequately sample the bison introduction area we surveyed three different prairie types: remnant prairies, restored prairies more than 15 years old and restored prairies less than 5 years old. To quantify potential differences in resource availability between the three prairie types we collected plant biomass and soil samples from three different “fields” in each prairie type. Both the plant biomass and soil samples were returned to the laboratory at Southern Illinois University, where they were processed. Forage quality samples were sent to the University of Wisconsin Madison Soil and Forage Laboratory for analysis of seven components of forage quality.
We found that the restored prairies less than 5 years old had almost twice the amount of plant biomass compared to the restored prairies more than 15 years old and more than twice that of the remnant prairies. Surprisingly, there was little difference in forage quality and stored carbon and nitrogen in soil among the three prairie types. The similarity in forage quality between the three prairie types may be attributed to prescribed burning, as all the fields were burned in April 2014 three months before we sampled them. Prescribed burning has been found to increase forage quality for up to a year after a fire and may have created homogenous plant biomass on the landscape. We expected soil carbon and nitrogen to be higher in the remnant prairies because these soils have not been tilled, a disturbance that has been found to reduce the storage of carbon and nitrogen in agricultural soils. The remnant prairies we sampled perhaps had a lower storage of carbon and nitrogen than expected because the soil was fairly shallow in comparison to the typical deep, loamy soils that characterize many remnant prairies.
The findings of this study suggest that bison may prefer the youngest restored prairies because there is simply more plant biomass available and little difference in the forage quality from the other prairie types. Even with these preliminary data it is still difficult to predict where bison will graze. Other factors that need to be considered are the dietary preferences of male and female bison and how prescribed burning creates a more heterogeneous landscape in the three prairie types. Post-introduction data have not been collected, so at this point any predictions of landscape use by bison is speculative at best. Maybe fate will strike again and I will be able to collect more data at Nachusa sometime in the near future.
Jason Willand is an associate professor of biology at Missouri Southern State University in Joplin, MO where he currently serves as the assistant department chair and chair of the conservation section of the Missouri Academy of Sciences.
By Ryan Blackburn
In the spring of 2013, I had little to no knowledge of tallgrass prairies or the various forms of life they held. I was an undergraduate at the time, and my class at Northern Illinois University had an opportunity to visit Nachusa Grasslands and receive a tour given by one of their dedicated stewards, Jay Stacy. As the class looked out across the beauty rolling over the tallgrass landscape, Jay directed our view downwards at our feet and started naming twenty or more plant species in just a little patch of dirt the size of a laptop. Jay also spoke of the rumors that bison may be coming to the landscape and how they were thought to have the ability to increase diversity of the prairie plant communities which already seemed teeming with life. This was the moment I realized that the tallgrass prairie and plant communities they held were something that I wanted to know more about. After a couple of growing seasons, a reintroduction of bison onto the landscape was accomplished, and my masters research was born.
Bison are large animals that require a lot of energy, which mainly comes from one family of plants, the grasses (Poaceae). Due to this selective grazing, bison create open space in their habitats for wildflowers to take root and increase the diversity of the tallgrass prairie overall. At least this is a summary of what had been observed in the research of remnant (never-plowed) prairies west of the Mississippi River which reintroduced bison as well. In hopes to recreate this tale of romance between bison and tallgrass prairies, Nachusa Grasslands reintroduced bison to their preserve of both remnant and restored lands. The question still remained: will their diet in this new area largely be made up of grasses, and how soon would we see changes in the plant communities following their reintroduction? To study this, I looked at both bison diet and differences of plant communities between sites with and without bison over a period of two years.
To figure out what the bison were eating, I used a technique called stable isotope analysis on bison tail hair pulled during the annual roundup. This allowed me to find signatures of plants within the bison hair and estimate these plants' abundance within bison diet. Better yet, I could cut bison hair into segments and look for seasonal changes. Through this analysis I was able to estimate major dietary groups of their diet between May 2016 and September 2016. I found that bison were doing what Nachusa brought them here to do: eat grasses (for the most part)! However, in late summer bison started to transition from largely grass species to wetland species and some wildflowers, something that had never been documented before. This was an unexpected shift that may lead to unforeseen consequences to wetlands, but further research is needed to speak to this.
Now that we know bison are mostly eating grasses during the growing season, we want to know how this might be impacting prairie plant communities. Attempting to answer this question, I, along with a team of dedicated plant enthusiasts, counted and measured percent cover of plant species across sites with and without bison. I quantified these communities in a variety of ways and compared them to see if bison were driving any differences between the two communities. Even though the bison had only been at Nachusa for three years, there were already evident changes happening within the plant communities. As predicted, areas with bison had more variation within their plant communities and had a higher ratio of native to non-native plants than those sites without bison. Further analysis shows that both variation and native to non-native ratios may be driven by bison preference of certain species such as bluegrasses (Poa compressa and Poa pretensis) suggested by a higher occurrence of these species in sites without bison.
The bison of Nachusa Grasslands were reintroduced to do a job: increase the diversity of plant communities. Though my research does not yet see an increase in diversity, it does suggest that bison are starting to go to work eating grasses and changing plant communities around them. Continued monitoring of these communities (especially those tasty wetland communities) is needed to gain a better understanding of bison impacts and how they progress in restored tallgrass prairies.
Ryan Blackburn just received his M.S. degree studying bison diet and their role in the restoration of plant communities in tallgrass prairies. Ryan is also looking at grazing impacts on a landscape scale using drone aerial imagery. In 2016, he received a $1,500 Friends of Nachusa Grasslands Scientific Research Grant for his "Determining Bison Diet and Bison Effects on Vegetation in a Chronosequence of Restored Prairie at Nachusa" project.
By Heather Herakovich, MS
Birds are known harbingers of spring. Although most stick around during the brutally cold Illinois winter, we don’t take much notice until they are everywhere in our yard, waking us up in the morning and pooping on our cars: spring time!
It’s finally springtime, and at Nachusa the birds are singing, vying for territory, and finding mates. These aren’t your typical backyard birds like the American robin and northern cardinal, who are your usual early morning alarm and repeating snooze. Nachusa holds a wide variety of bird species, including some of the ones in the most need of conservation: grassland birds. They come with funny names like bobolink and dickcissel, and in all shades of brown and yellow and sometimes black.
Grassland (prairie) birds are declining at a faster rate than most bird species, and a majority of this has been caused by habitat loss. Illinois is the prairie state, but only one hundredth of its original prairie remains. Places like Nachusa are doing their best to restore the agriculture fields and recreate the best prairie as humanly possible. Doing this requires a lot of hard work, hours of picking seed, planting seed, removing unwanted plants, burning portions of the prairie and mowing. The birds seem to be responding to this management fairly well. However, there is an elephant in the room, or shall I say a bison in the prairie.
American bison are our national mammal, and rightfully so. These large herbivores used to roam most of the contiguous United States, until they were hunted to near extinction. I’m sure you’ve heard the story. But now they’re back! Grazing is a crucial disturbance in prairie habitat, providing habitat for a lot of species and open space for a lot of plants. But how will birds respond to this large, iconic grazer on its new home in Franklin Grove, Illinois? When I started my graduate degree at Northern Illinois University in 2013, I was able to start trying to answer that question more specifically by looking at how their nests were going to be impacted by bison.
Bison can impact bird nests in a variety of ways. There are the obvious negative direct ones like trampling and dislodgement, but there are also some not-so-obvious impacts. These impacts can be either positive or negative and can affect the nesting habitat, nesting material, clutch size, and ultimately the survival of the chicks until they leave the nest (nest success). Seeing if bison are impacting nest success means I must find the nests first. This is the most difficult part. They are roughly the size of a compact disc, made from the vegetation they are in, and wickedly hard to find. If you come by Nachusa early in the morning this summer, I’m sure you’ll see me walking in the prairie, waving around a stick, and waiting “patiently” for a bird to fly from the vegetation.
Although difficult, watching these nests through time is a very rewarding experience. I’ve seen nests being built, eggs being laid, chicks hatching, and chicks leaving the nest. Please don’t try this at home, though. Nests are sensitive to human disturbance, and I follow specific protocol to not influence their nest success. Bison don’t seem to be influencing their nest success either, negatively or positively. This is good news. They are one of the main sources of disturbance in the prairie, and it is a relief that they are not trampling nests of birds in decline, at least four years post-reintroduction. Watching these nests is only a part of my graduate research. I am also looking at how bison may influence nest predators, brood parasitism by brown-headed cowbirds, and what bird species are present. So far, I am not seeing anything change enough to be consider a bison impact. Time will tell if there will ever be a noticeable impact of bison on grassland birds. If I were here in ten years, I would try to find out.
The beautiful prairie and bison are a great reason to visit Nachusa, but don’t forget about the birds. Sure, they all look similar and are hard to spot, but they are our harbingers of spring and make the prairie sing in the summer.
Heather Herakovich is a PhD graduate student at Northern Illinois University. Heather studies grassland bird nest density, nest success, and species composition in restored plots of varying age as well as remnant control prairies. Heather is attempting to quantify the effects of bison reintroduction, prescribed fire, and restoration age on grassland bird populations at Nachusa.
First things first: bison or buffalo? Bison is the scientific and more accurate term. Bison are not buffalo, like the African buffalo (Syncerus caffer) or water buffalo (Bubalus bubalis). The word "buffalo" has had a long usage on this continent and has accumulated so many layers of cultural resonance that it has also become an acceptable term.
There have been many ancient ancestors to our modern bison. Possibly arriving on the continent during one of the ice ages, Bison priscus, or steppe bison, may have originated in Siberia. Perhaps here as early as 600,000 years or as late as 300,000 years ago, B. priscus was larger than the modern bison, measuring at the shoulder about six and a half feet. B.priscus' horns were about one and a half feet in length.
After B. priscus died out, Bison latifrons became dominant. This bison was approximately 20 percent larger than modern bison, standing over 8 feet in height, with 7 foot horns. Bulls may have weighed as much as 4,000 pounds. It is the largest bovid ever found. This species was mainly located in the western part of the continent and may have arrived here 300,000 years ago.
Following B. latifrons was Bison antigus, much smaller bodied with smaller horns. This is the most common large herbivore found in the La Brea tar pits. They existed here for only about 12,000 years, to be replaced by Bison occidentalis. Again, notable for a smaller size than previous species, with horns that pointed upwards and not forward, B. occidentalis occupied the continent for some 5,000 years.
Bison bison, the modern bison, is the smallest bison species to ever occupy North America but is also the most prolific. Arriving between 12,000 to 10,000 years ago, estimates as to number have varied over the years, but scientists now agree that about 30 million bison roamed over the Great Plains, a vast grassland formed after the last ice age about 10,000 years ago. By the time of European settlement, B. bison were found in all parts of the present United States, except for the states of Connecticut, Rhode Island, New Hampshire, Vermont, and Maine, grazing in open grasslands around the edges of forests.
It was in the 19th Century that bison numbers dwindled down to almost extinction level. Reasons for this are varied and are still debated by scientists. Climate change was a factor, with long periods of drought affecting the grasslands. The settlement of the West reduced grassland habitat. European reintroduction of the horse to the continent greatly improved the efficiency with which native tribes hunted the animal. In 1869, the transcontinental railroad was completed, while the next year a new tanning process was developed that made bison hide much more pliable. With the new tanning process and an efficient means to get the hides to market, the demand for buffalo hides exploded. It is estimated that as many as 5,000 hide hunters, armed with the latest in firearm technology, descended on the plains, killing millions of bison. This may or may not have been sanctioned by the military, looking for ways to keep hostile tribes in check by diminishing their food supply. This is a controversial topic, not resolved presently.
On the other hand, it was in the 19th Century that measures began to be taken to protect bison. In 1872, Yellowstone was made the country's first national park, with a population of bison grazing its grasslands. In 1894 the Lacey Yellowstone Protection Bill was passed to protect all wildlife in the park, including the last 25 wild bison of Yellowstone. In 1905, the American Bison Society, composed of politically powerful men, was founded to help save the bison and make the public aware of their dire situation. Teddy Roosevelt, then President of the the United States, was made honorary president of the society. This was followed in 1908 by the creation of the National Bison Range in Montana, established to protect wild bison from extinction. These measures of protection led to a number of growing wild herds.
More recently, The Nature Conservancy has taken steps to insure the continuation of wild bison herds roaming free in restored prairie habitat. Wind Cave National Park in South Dakota has maintained genetically pure (no cattle genes) bison but can only sustain 500 animals. Partnering with Lame Johnny Creek Ranch, a privately owned ranch in South Dakota, The Nature Conservancy maintains a herd originally from Wind Cave, to increase the genetically pure bison at "satellite" sites in various locations. These bison can now be found at Broken Kettle Preserve in Iowa, Dunn Ranch in Missouri, Tallgrass Prairie National Preserve in Kansas, Midewin National Tallgrass Prairie near Joliet, Illinois, and our own Nachusa Grasslands.
On May 9, 2016, President Barack Obama signed into law the National Bison Legacy Act, making bison the United States' National Mammal. It is a hopeful sign that a mammal that once ranged freely across the entire continent in the millions, and then was almost lost to extinction, is once again making a comeback.
You too can be part of the legacy of protection by supporting organizations that protect their habitat. Visit http://www.nachusagrasslands.org/donate.html to see how you can help.
Lott, Dale F. American Bison: A Natural History. Berkeley, CA: University of California Press, 2002.
Flores, Dan. American Serengeti: the Last of the Big Animals. Lawrence, KS: University Press of Kansas, 2016.
Savage, Candace. Prairie: A Natural History. Vancouver, B.C.: David Suzuki Foundation, 2004.
The Nature Conservancy. "Putting Bison Back on the Prairie." (2016). Retrieved from: http://www.nature.org/ourinitiatives/regions/northamerica/unitedstates/northdakota/explore/putting-bison-back-on-the-prairie.xml.
This week's blog was written by Charles Larry, a volunteer and photographer at Nachusa. To see more of his images, visit charleslarryphotography.zenfolio.com.
Nachusa welcomes the newest member to the herd, a bright rusty-red 40-60 pound calf. The calf was first spotted at 12:40 on Apr. 24 by Susan Kleiman. Yesterday the new calf was easily seen from the visitor entrance, so bring your binoculars and maybe you will spot Nachusa’s newest addition!
Herd total: 75
Today’s blog was brought to you by Charles Larry, a photographer for Nachusa
(charleslarryphotography.zenfolio.com). Photos taken 4-25-2016.
I am a nature photographer, a freelance graphic designer, and steward at Nachusa's Thelma Carpenter Prairie. I have taken photos for Nachusa since 2012.
I have been a high school French teacher, registered piano technician, and librarian. In retirement I am a volunteer historian at Lee County Historical and Genealogical Society.