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.
As a native of Utah, I never gave much thought to tall grass prairies. I was always obsessed with the mountains, assuming I would work in that ecosystem. Yet, here I am in Illinois, working in a tall grass prairie for my thesis. Although I never anticipated ending up here, I am so glad that I did.
My advisor, Dr. Holly Jones, introduced Nachusa to me as the perfect place to conduct research. It has a chronosequence of sites, a bison unit, a non-bison unit and units with different burn intervals. I understood what she meant by the perfect place, but I couldn’t fully appreciate it until I became immersed in the potential of Nachusa. I am continually finding myself inspired with new research questions and ideas, to the point where I swear I could stay here forever.
My research interests revolve around predators. Predators have fascinated me since I was a kid pretending to be a lion. There is a beauty and grace about predators. They are fierce, powerful, and incredibly influential in an ecosystem. Predators can shape an entire ecosystem through hunting, creating fear that results in behavioral changes in their prey. These effects can ripple down the food web all the way to impact decomposition.
Nachusa is unique place to study predators. Historically, wolves were the top predators here. Since they were driven to local extinction in the 1800s, coyotes have taken over that role. This change in “top dog” has major implications for the way an ecosystem functions and which prey species are most abundant. That in itself is interesting. However, in addition, Nachusa is a rich and diverse landscape surrounded by agricultural fields. These conditions can be very supportive of coyote and fox predators. Furthermore, I discovered that the coyotes at Nachusa are depredating a state-listed turtle species many of us know and love: ornate box turtles. This makes understanding the role coyotes play at Nachusa even that much more important.
My research focuses on how coyote removal impacts small mammal prey species. Using stable isotope analysis, I investigated the diet of coyotes at Nachusa. The first step in the process was getting tissue samples from consumers (i.e. coyotes) and all the prey sources they ate. I tried countless times to entice coyotes to non-invasively “donate” their fur, but they just wouldn’t cooperate. In the end, the supportive community at Nachusa graciously collected nasty hair samples from road kill for me. (Thank you all so much!)
I’m currently looking at seasonal effects on coyote diet; the coyote hair is cut into segments and examined. Food availability in the prairie shifts over the seasons, so this method could provide some interesting insights as to what coyotes are eating when. Potentially, this could tell us more about when ornate box turtles are at highest risk for coyote depredation!
We now know that the Nachusa coyotes are opportunistic, generalist feeders. They hunt and eat small mammals in the greatest proportion collectively, but have a wide variety of dietary items. This is hardly surprising considering the menu of small mammals that are out there!
I have come to love Nachusa and each and all of its ticks. I can’t believe my time as a researcher here is coming to an end. Not only have I fallen in love, but my family has too. We will miss and cherish our time spent at Nachusa.
Kirstie Savage is a graduate student in the Department of Biological Sciences at Northern Illinois University. To read more about her work, visit the Jones Lab webpage.
Nachusa’s small creatures help citizen scientists monitor stream quality. Collection, identification, and a tally of macro-invertebrates from the local streams are used as an indicator of stream health. The monitoring is done through a statewide program called Illinois RiverWatch, established to help determine stream water quality throughout the state and provide a warning of potential problems. At Nachusa, the program was started in the spring of 2014 before the bison arrived, so RiverWatch is not only used to monitor stream health, but also to help identify changes due to their introduction. This is the fourth year collecting RiverWatch data in three Nachusa streams: Wade Creek, Clear Creek, and Johnny’s Creek.
Illinois RiverWatch trains citizen scientist volunteers to collect, identify, and preserve important indicator species of macro-invertebrates found in streams throughout Illinois. Macro-invertebrates are invertebrates large enough to see with the naked eye. Examples include insect larva, snails, and aquatic worms. One person in the stream monitoring group is required to have the eight-hour RiverWatch training class; four hours in the classroom and four hours hands on in a stream. At Nachusa, we are fortunate to have several trained monitors and interested volunteers lead by Mary Vieregg. Others that often join in the fun are Cindy Buchholz, Mary Meier, Jan Grainger, Matt Friberg, Tim Ngo and myself. Interested people who have not been trained by RiverWatch can participate in the stream monitor with a trained lead.
A site is selected and the locations are documented and approved by RiverWatch. The same site and locations are used each year, so changes from year to year and over time can be observed. At the site, the first step is to mark off the sampling area with flags 50 feet and 100 feet upstream and downstream from the selected site. Then, a map is sketched marking stream contours, significant features, and the day's sample locations. In addition, water depths, stream velocity, stream color, and temperature are recorded. Lastly, the vegetation around the stream is noted, along with the amount of shade cover; the stream bottom substrate is observed and recorded. Pictures can be taken and included with the sample data. Much of this data is recorded after the dip net hits the water in order to minimize any disturbances to the stream and the macros living in it before the collection.
The preferred collecting tool is the dip net. Designed with a sturdy cloth sleeve and mesh bottom, water can easily pass through and allow macros to collect in the bottom. There are five stream habitat types that RiverWatch samples, using the dip net collecting techniques. In order of preferred use:
Once the samples are collected and placed in buckets, the challenge is to pull the fast-moving macros from their watery homes. This is done using a shallow white pan, forceps, eye droppers, and carbonated water to help slow the critters down. Once captured, the macro makes the ultimate sacrifice, as it is deposited in a vial of pure alcohol for later identification and recording. All the macros taken can be combined into one sample. Once all the macros are pulled from the shallow white pan and put in vials, the gear is packed up and the crew returns to the barn for lunch. After lunch the work of sorting, identifying and counting begins.
Macro invertebrates can be seen with the naked eye, but for identification some of the key differences only become clear under a microscope. For example, mayflies fall into seven categories and key features on the gills, legs, and antennae are more easily seen through a microscope. Damsel fly larva, whether broad-winged or narrow-winged will determine their indicator number. Dragonfly larva are large and don’t need to be identified down to species, only that they are present and the number found. The process of identifying, sorting, counting is continued until the specimens are determined and recorded. The vial containing all the day's collection is labeled and sent to the RiverWatch administrator, who then forwards it on to professionals who double-check identification and the count. Feedback is then provided to the citizen scientist to help improve identification in the future.
Each macro used as an indicator species is assigned a number. The lower the number, the more conservative the species and the less tolerant of pollution and other disturbances. A formula, based on the assigned number of each species, the total count of each species, and the number of organisms found, is used to determine the Macro-Invertebrate Biotic Index (MBI). The lower the MBI number, the higher the stream quality.
Nachusa stream quality is good in Clear Creek and fair in Wade and Johnny’s Creek. It is too early to see a trend in improvement or degradation of water quality. An effort is made to sample the streams close to the same date each year, but an annual variance in weather conditions can account for some difference in the MBI. Only after many years of monitoring are trends likely to be seen. Following the introduction of bison, changes to the stream banks have been observed. In the sample area around Johnny's Creek, the vegetation has been eaten or trampled. Stream banks that were heavily vegetated are now bare. Near Wade Creek bison hair was found on the plants, but no disturbance was noted in the Wade Creek sample area. The changes in streams being made as a result of restoration efforts and the introduction of bison won't be measured in months or even years, but in decades and centuries. Careful observation, good science, sometimes unnerving patience, and prudent management will help restore the portions of these streams that run through Nachusa back to a functioning and evolving ecosystem.
Note: Clear Creek is outside of the bison enclosure.
To volunteer for the RiverWatch program at Nachusa, contact Mary Vieregg. For more information about citizen scientist training, visit the website for Illinois RiverWatch .
The blog today was written by Paul Swanson, a volunteer citizen scientist for Nachusa.
The bison reintroduction has been exciting for everyone involved with Nachusa—staff and stewards, volunteers and visitors, and especially scientists. The project provides a unique opportunity to measure the impacts of these animals and their actions on the entire restored prairie ecosystem. I’m fortunate to be part of a small army of researchers and students working closely with Nachusa personnel to understand how bison influence plants, animals, and other organisms.
Anyone who has had the opportunity to spend time within the bison units over the past 2 years has undoubtedly seen evidence of these giant herbivores: dung! In addition to grazing on plants and wallowing in dirt, bison play an important role in nutrient cycling by depositing concentrated piles of plant material and nutrients around the prairie. Across the landscape, this may provide hotspots of growth for some plants, adding to the overall diversity at Nachusa.
An inconspicuous group of insects help to carry out this nutrient–cycling process. Dung beetles feed on animal waste, and many species collect dung as a food source for their offspring. Some species famously form it into spheres, and roll these “dung balls” away to bury and deposit eggs. Other species tunnel below the dung patty, building chambers where dung is stored and beetle larvae can develop. And some species are “dwellers” who simply dive in to fresh dung and start to feast, laying eggs along the way. When these eggs hatch, the larvae feed, pupae, and emerge as adults, completing their entire metamorphosis in a single patty before heading off to mate and start the process over again in fresh patty.
Burying small bits of dung in the soil helps make nutrients accessible to plant roots. In the soil, microorganisms like bacteria and fungi convert organic materials into inorganic forms available to plants. This can represent a significant amount of the nutrients. As dung dries, much of the nitrogen can be lost to the air as ammonia volatilizes. This is why dung beetles are important for ranching: every bit of nutrients back in the soil rather than lost to the atmosphere means more fodder for livestock.
So it was a reasonable assumption that the dung beetle community at Nachusa would respond positively to the introduction of several dozen large, dung-producing herbivores to the prairie. I credit Dr. Ken McCravy from WIU for first suggesting that we should investigate these communities. Over the past two years, with support from the Friends of Nachusa Grasslands, I have been working with NIU students to survey the dung beetles to determine which species are present and how their abundances differ between sites with and without bison. We use pitfall traps, baited with fresh bison dung, to collect beetles that are later pinned and identified under a microscope in my lab at NIU.
Our preliminary results are exciting: we have documented at least seven species, including rollers, tunnelers, and dwellers. The two most common species are Onthophagus hecate, a widespread species, and Onthophagus knausi, a uncommon species whose range extends west and south through Kansas, Oklahoma, and Texas. The other species are much less common but include the large, blue-black Geotrupes opacus and the spectacular rainbow scarab, Phanaeus vindex.
As a preliminary result, the presence of bison doesn’t seem to have a big effect on abundance, as some bison-free sites have high numbers of beetles. But this may not be surprising given how mobile these insects are. They can fly and specialize in seeking out their preferred food. Cattle pastures surrounding Nachusa likely provide population sources as well.
Over the next two years, we will be investigating these dung beetle communities in more detail. A Master’s student at NIU will be combining observations of dung decomposition with beetle measurements to understand how different species contribute to dung processing. Ultimately we hope to understand how the management actions that maintain high plant diversity at Nachusa (such as prescribed fire and grazing) affect beetle communities and their ability to process dung.
Keep an eye on fresh dung patties and you may see these small but fascinating insects carrying out some of the invaluable “dirty work” that keeps the prairie ecosystem healthy and biodiverse!
Nick Barber is an assistant professor in the Department of Biological Sciences at Northern Illinois University. To read more about his work, visit the Barber Lab webpage. Thank you Nick, for being our guest blogger this week!
As I prepare this week to graduate with my Master’s degree from Northern Illinois University, I found myself reflecting on how much my experience at Nachusa shaped my life. I fell in love with Nachusa in 2013, after a volunteer work day collecting seed for one of my courses at Northern Illinois University (NIU). After less than an hour out in the field, I realized how much natural beauty I had missed out on while growing up in “The Prairie State,” and I was determined to make a difference. Standing on that knob surrounded by smiling stewards, seeds and sunshine sparked an everlasting passion in me to conserve, protect, and connect communities to their natural areas.
I was honored to research the effects of bison grazing and prescribed fire on small mammal communities at Nachusa for my graduate degree. Being able to witness the reintroduction of bison to the prairie and to be part of the team of scientists documenting their impacts is a once in a lifetime experience that I will cherish. I had the privilege of witnessing first–hand how different mice, voles, and ground squirrels thrive in this ecosystem filled with towering grasses and successional bursts of flowers.
Bison are truly amazing and I honestly was clueless as to how they would influence my research, and the herd always made sure to keep me guessing. It is really no joke that bison can be hard to find in the tallgrass, and I spent just as many hours fascinated watching them as I did capturing little critters. In early 2015 when I first saw that they had been through one of my trapping sites, I laughed because they had kicked around a few traps and bent over poles marking where the traps were, making the message loud and clear that my equipment was apparently in their way as they grazed.
That following summer I saw many bison grazing patches dotted with the peaking heads of 13–lined ground squirrels and began to capture them more frequently in the areas the bison stuck around in. It was surprising to me how quickly the deer mice returned to the areas that were recently burned, making them appear like giants among the emerging vegetation. The elusive capture of specialist small mammals like the western harvest mice and meadow jumping mice were always a treat to photograph. From the excitement of not knowing which little small mammal I was going to capture to the increasingly frequent “bison delay,” my adventure was filled with many fun experiences that definitely made me a prairie enthusiast for life.
My time at Nachusa documenting this healthy and diverse ecosystem, filled with so many amazing small mammals, are among the best memories I have spent with friends and family. Watching the seasons and the colors of the flowers change was always the highlight of my time out there. I will never forget the colors of that first sunset and how the fog rolled between the remnant knobs as the sun came up the next morning. At that time I never would have guessed that capturing adorable small mammals in this breathtaking landscape would bring so many people of diverse backgrounds together.
Sharing my time with all of you in the prairie truly inspired me to pass on the Nachusa spirit and help connect more people with their natural areas. Recently I accepted a position with The Nature Conservancy in Ohio as their Conservation and Volunteer Coordinator. I can only hope that I am able to pass along even a small bit of the Nachusa spirit that makes us more than volunteers or nature enthusiasts, but rather a family working together for the benefit of everyone through restoring and protecting nature. For this I graciously thank the amazing people who made Nachusa my home away from home and for a prairie state of mind . . . now and forever.
Today’s author is Angie Burke, a graduate student and researcher from Northern Illinois University. To read more about Angie's research, visit The Jones Lab at NIU.
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.