Small Mammals—The Little Things That Matter

​By Angie Burke
Volunteer Coordinator, The Nature Conservancy

It's shortly after sunrise as my volunteers and I begin to check the small mammal traps we set the night before.

​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.
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Dr. Holly Jones

​​This research, established by Dr. Holly Jones at Northern Illinois University in 2014, focuses on understanding how time since restoration began, fire frequency, and bison grazing all play a role in the variety of small mammals we encounter. These creatures play important roles in various ecosystems and respond to pressures above—predators like hawks and coyotes, and below—the plants they rely on for food and shelter.

​​For three years I had the honor of leading this project of collecting data on the preliminary changes in the “critter community”— and there was never a dull moment. ​From bison delays, where the bison were happily

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. 

Left to right: meadow-jumping mouse, deer mouse, thirteen-lined ground squirrel, and white-footed mouse

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. 

It's spring, so the traps are easy to see, as a line of them are checked right after sunrise.

​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. 

I'm measuring the tail length of a deer mouse. Before the small mammals are released they are identified, weighed and measured. A chip is also inserted under the skin so I know if an individual returns to the traps multiple times. Many did!

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.

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Angie Burke and a small mammal research helper

As a Northern Illinois graduate student, Angie Burke researched small mammals at Nachusa from 2014-2016. Her research was recently published in the Natural Areas Journal. Now Angie works for The Nature Conservancy in Ohio as a Conservation and Volunteer Coordinator.