Assessing Prairie Restoration Through the Eyes of Small Mammals – Part 1

We’ve taken another step in the right direction…

Over the last several years, we’ve begun to evaluate our prairie restoration work beyond just looking at plant communities.  Our primary objective for restoration is to functionally enlarge and reconnect fragmented remnant (unplowed) prairies by restoring the land parcels around and between them.   (See more on that topic here.)  Because of that, it’s pretty important that we look at whether or not species – plant and animal – living in those remnant prairies are actually using and moving through our restored prairies.   In 2012, we brought James Trager and Mike Arduser to our Platte River Prairies to help us start measuring our success in terms of ants and bees, respectively.  We’re still early in that effort, but things look good for both so far.  Most ant and bee species living in our prairie remnants are also showing up in nearby restored prairies.

A deer mouse peers out of the thatch.

A deer mouse peers out of the thatch.

Now we’re hoping to find similar patterns with small mammals.  Mike Schrad, a Nebraska Master Naturalist, has volunteered to help us see whether the small mammal species in our remnant prairies are also in adjacent restored prairies.  We’ve begun by looking at a single 200 acre prairie complex that consists of a remnant prairie surrounded by several restored prairies (former crop fields seeded with 150 or more plant species back in the mid-1990’s).  Mike came out for three nighttime sampling periods in 2013 to see what he could catch in the remnant prairie and one of the adjacent restored prairies.

Mike and I have been looking over the data from this first year, and I’m pretty encouraged by what he’s found so far.  He caught four species in the remnant prairie, and all four were also in the adjacent restored prairie.  In addition, a fifth species, the short-tailed shrew, was caught only in the restored area – but only once.  The five mammal species he caught were:

Prairie vole (Microtus ochrogaster)

Meadow vole (Microtus pennsylvanicus)

Harvest mouse (Reithrodontomys sp.)

Deer mouse (Peromyscus maniculatus)

Short-tailed shrew (Blarina hylophaga)

The relative abundance data for each species caught by site are interesting (see the table below), and reflect the fact that the sites had been largely rested from fire and grazing during the last couple of years.  Voles are attracted to the kind of thatchy grassland habitat found in ungrazed/unburned prairie, and they were caught more often than any other species in our site.  The higher numbers of voles in the remnant prairie might indicate a more dense vegetation structure there than in the restored prairie (or might have just been happenstance).  It was also interesting to see more harvest mice caught in the restored prairie, though the total numbers were low enough that we aren’t drawing any strong conclusions from them.  The total number of animals caught by species and site are below:

2013 Data

On the one hand, seeing the same species in both remnant and restored prairie might not seem very surprising.  Our restored prairies have the same plant species in them as the remnant prairies, and are managed the same way.  It seems likely that small mammals can find everything they need for food and shelter there.  On the other hand, it’s dangerous to blindly assume that we’re providing for the needs of all species when we restore prairies.  The mouse and vole species we saw this year have been pretty well studied, but we still don’t know everything about what they need to survive.  What looks like two identical habitats to us might be very different to a 2 inch tall little critter.  For those reasons, it’s nice to see some support for our assumptions – though we still need much more data.

Mike Schrad records data from one of his trapping efforts.  Mike is a Nebraska Master Naturalist, one of many volunteers being deployed around the state to help with conservation and science projects.

Mike Schrad records data from one of his trapping efforts. Mike is a Nebraska Master Naturalist, one of many volunteers being deployed around the state to help with conservation and science projects.

Over the next month or two, Mike and I will be planning future sampling efforts.  Ideally, we’ll repeat the same kind of trapping he did in 2013, but do so at other sites were we have adjacent remnant and restored prairies.  If we continue to see the same pattern of use – the species in the remnant prairie also using adjacent restored prairie – I’ll start to feel even better about our ability to defragment prairies from a small mammals’ perspective.

However, even if we continue to see results similar to this year, there will be more to learn.  First, there are several less common species of small mammals in our prairies (we think) that weren’t caught this year.  Two of those are plains pocket mouse and plains harvest mouse, both of which could be in our upland areas and are priority conservation species in Nebraska.  Another is Franklin’s ground squirrel, a species we see periodically in our lowlands, but which has disappeared from most tallgrass prairies in the eastern U.S.  I’d like to know that we’re creating habitat for those less common species, as well as for the common ones we caught this year.

There is still a lot to learn about how well our restored prairies are working.  However, with each step we take, I feel a little better about our ability to reduce the impacts of habitat fragmentation by restoring strategic parcels around and between prairie fragments.  Knowing we can do it doesn’t make it economically or socially feasible, but those other factors are irrelevant if we can’t solve the technical issues first – and prove that we’ve done so.

One step at a time…

21 thoughts on “Assessing Prairie Restoration Through the Eyes of Small Mammals – Part 1

  1. Very interesting, I really like the idea of re-assessing conservation work from the point of view of other species rather than the obvious ones. It often takes the work of a lichenologist for example to make me re-evaluate woodland management designed to generally improve woodland structure. Grassland mammals on the prairie need a variety of sward structures and food sources I guess. Really good informative post, thanks

  2. I love getting just another little peek into the diversity found on prairies and I really look forward to hearing more as additional trapping is conducted. One question – what was the size of the remnant prairie, and what size the restored? I only ask to gain a sense of scale; I understand that the trapping was no doubt designed with relative size taken into consideration.

    • Teresa, the remnant site was about 90 acres and the restored field we sampled was 45. Total area of the prairie those two are embedded within is about 200 (there are two other restored fields on the other side of the remnant).

  3. This is quite interesting, Chris. It is a nice start, but I think the study could be enhanced by adding a control of sorts, sampling what occurs in non-prairie fields in the area, since the critters in question are generalists. As you say, colonization by some of those rarer elements woudl be good to see.
    Years ago, I had a student doing small mammal sampling here on our prairie plantings. One striking find was the near abandonment of recently burned sites. Various predators really have a “hay day” after burns. Hawks fly over while the site is still smoking, and for days thereafter, searching for exposed mousies skittering about, and coyotes dig up seemingly every vole warren or rabbit nest. If there is snow after a burn that leaves some patches unburned, the small mammal tracks in and out of the unburned patch are very numerous.

    • Thanks James. You’re absolutely right about having more to do! There have been a couple of studies of small mammal responses to patch-burn grazing, showing some very big differences in mammal community composition relative to time since last burn. As you say, recently burned areas can be tough places to live – they sure don’t have much cover – but the recovery phase is pretty nice. I think your idea about sampling adjacent areas is a good one – it would be best, of course, to sample across an entire section of landscape that includes prairie, woodland, cropfield, to see the dynamics of how populations colonize and recolonize after land use changes and disturbances. One of my big hopes is to somehow figure out how far some of these animals can move across the landscape to find appropriate habitat when conditions change where they’ve been living. That’s a big question with lots of implications for how we manage prairies.

  4. Chris,
    I just attended a symposium on grazing for conservation at the Midwest Fish and Wildlife Conference. There was a grad student studying small mammal use of the patch burn graze system that has been implemented on Konza Prairie.
    I’ve attached the link to the abstract; his talk is titled, “Small mammal responses to patch-burn grazing”.
    Thought it might be a useful contact to make considering your interest.

  5. Chris i was just thinking how hard it is to connect these small restoration/remnants together and wondered if using ditch rows as connecting strips was possible? It could be easier to convince farmers of this if presented right than some other methods that could infringe on there land. I know all the chemical use might make this impractical in some areas.

    • Ernie, I’m not current on the research that’s been done on this topic (I’m actually hoping to become more current on it soon) but my impression is that those connecting strips can be very important for helping small mammals colonize new areas and move around the landscape. I know that there are often high numbers of some small mammal species along cropland edges because they can forage in the fields, especially in the fall and winter. If you walk the edge between cropfield and prairie in the snow, there are often incredible numbers of mouse trails heading back and forth between them.

  6. I’d be interested in learning more about how to trap and ID small mammals so that I can get a better inventory of these animals on my property. Do you have any good references or guides to recommend?

  7. Hi Chris, interesting results. Could you elaborate on what method(s) you used to trap the animals? In the areas I work on (in Australia) we generally rely on Elliot traps and pit-fall trapping for small ground mammals. Motion-sensing cameras seem good but it can be pretty difficult to distinguish one species from another using just this method.

    • Matt and Patrick – for this first attempt, we just used simple snap traps (mousetraps like you’d buy at the hardware store). We would like to use Sherman live traps or some other non-lethal method as we expand our effort and especially when we start sampling areas where we’re more likely to catch rare species. For the first year, we were working low budget and quick. In addition, some of the species can be really difficult to distinguish from one another (grooves in teeth, etc. to separate them!) so snap traps made it easier to get familiar with identifications. Matt, I’m not an expert on small mammal trapping, so don’t rely on me for advice! Patrick, if you want to do some trapping on your land, be sure to check with the state DNR first. In Nebraska, we had to get a permit to trap small mammals and get approval of our protocols, etc. I assume you’ll have to do the same, and you’ll also want advice about how to avoid some potentially dangerous diseases that can be carried by small mammals.

  8. Chris,

    You mentioned a few at-risk species that you hope to find someday but how many total small mammal species are possible for your area?

    Thanks, David

    • David – a recent graduate student project on our neighbor’s properties (and some of ours) found 11 species. I don’t think I’ve ever seen a comprehensive list of what’s possible here (though I’m sure someone has one) but it’s likely slightly higher than 11. Small mammals are like birds in that they have preferences for particular types of habitat structure. In our work this year we focused on one type of structure, so limited our catch some. That was fine because we were really comparing restored vs. remnant and it was a first attempt. To be comprehensive, we’ll want to know whether the same small mammal species use the same habitat structure in both restored and remnant prairie. That will be a much bigger challenge to test!

  9. Apparently the short-tailed shrew has venomous saliva and eats voles. How cool that we have some on our prairies! Way to go Mike!

  10. I wonder what changes would occur if all rodents were excluded from a prairie. In contrast, I wonder what changes would occur if rodent predators were excluded. Rodents chew a ring of bark off of many woody species during the winter. Would certain opportunistic woody species retreat with more pressure from rodents? It is already known that rodents devastate a number of rare prairie species. Do the large swings inherent in rodent populations provide opportunities for diversity?

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