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.
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:
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.
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…