What I Look For When I Walk Through My Prairies

Back in August, I posted some questions to readers about what they look for when evaluating their own prairies.  I got some excellent responses, which I really appreciated.  If you missed them, you can re-read that post and those comments here.

Walking around a prairie and getting a read on what's happening is probably the most important part of prairie management.  This is Scott Moats, The Nature Conservancy's Broken Kettle Grasslands, Iowa.
Walking around a prairie and getting a read on what’s happening is probably the most important part of prairie management. Scott Moats, The Nature Conservancy’s Broken Kettle Grasslands, Iowa.

As a follow up to that, here is more detail about what I think about as I walk around my family prairie, or one of our Platte River Prairies.  Of course, sometimes I just hike around and enjoy the day, but this post is about what I focus on when I’m evaluating our management and considering ideas for next steps.  We collect some relatively formal data on some sites, but most of our management decisions are really based on the kind of observation and evaluation I lay out here.  I’m certainly not trying to talk you into doing exactly what I’m doing – especially because what I look for is tied to my particular objectives, not yours.  Instead, I’m hoping that I might spark some ideas you can incorporate into your own decision making processes.

To start with, the basic objective at both my own prairie and those I help manage professionally is the same.  I want to provide a shifting mosaic of habitat structure patches (short, tall, mixed-height, etc.) so that the quilt pattern of those patches looks different each year.  I assume that a dynamic management regime like that will support high plant diversity because it doesn’t allow static conditions that allow a few plant species to become dominant.  I also assume that those shifting habitat patches will facilitate a healthy community of insects, birds, mammals, reptiles, and other life – above and below ground.  These are not blind assumptions; they are based on my own experience and research, along with that of many others.  (You can read more about those assumptions here.)

Grazing can create very important habitat structure such as this short grass/tall forb habitat at our Platte River Prairies.
Grazing can create very important habitat structure, including this short grass/tall forb habitat at our Platte River Prairies.  This habitat allows for easy movement along the ground, but provides plenty of overhead cover as protection from predators and the hot sun.

Not surprisingly, the first thing I look for, then, as I walk around a prairie is the pattern of habitat structure.  I hope to find the full range of variation, from tall and dense vegetation to almost bare ground.  Even more importantly, I want to see some of the important intermediate habitat types – especially short-cropped grass with tall forbs (wildflowers), which is incredibly important for many wildlife and insect species.  If I can find all of those habitat types, and they’re in different places than they were last year, I feel pretty good.

Next, I look at the plant community.  Plant diversity is an important foundation for invertebrate and wildlife diversity, so I want to see a rich diversity of plants as I walk around.  I also want to see that diversity at both large and small scales.  Across the whole prairie, I’d hope to find at least 100-200 plant species (though I certainly don’t count them every time) but I should also be able to count at least 10-15 plant species within arms’ reach if I kneel on the ground.  These numbers vary, of course, based on geography, soil type, etc., so they may or may not be reasonable at your particular site.

As I look at plant diversity, I want to see habitat patches with an abundance of “opportunistic” plants.  These are species that thrive in the absence of competition.  Depending upon your point of view, you might also call them “colonizers” or even “weeds”, but when they are abundant, it means that nearby dominant plants have been weakened.  We try to periodically knock back the vigor of dominant plants (especially grasses) through fire, grazing or mowing, to help less dominant plants maintain a foothold in the plant community.  A flush of opportunistic plants is an indicator of success because it shows that we successfully opened up that space and other plants are taking advantage of it – and not just the weedy ones.  Finding seed heads, and even new seedlings, of slower-to-colonize plant species (purple prairie clover, entire-leaf rosinweed, leadplant, etc.) within those weedy patches makes me feel even better.

Black-eyed susan  is a showy example of an opportunistic plant species that thrives when surrounding vegetation is weakened.  Other species I look for include ragweeds, hoary vervain, annual sunflowers, ironweed, ragwort, annual thistles, and many others.
Black-eyed susan is a showy example of an opportunistic plant species that thrives when surrounding vegetation is weakened. Other  opportunists I look for include ragweeds, hoary vervain, annual sunflowers, ironweed, ragwort, annual thistles, and many others.

In sites where cattle are present, I spend time looking at what they’re eating and not eating, as well as which parts of the prairie are being grazed most and least.  In our patch-burn grazed prairies, we expect most grazing to take place in recently-burned areas, so I check to see if that’s happening.  Often, cattle target their favorite grass species first and then graze wildflowers only if they’ve already eaten the best parts of those grasses.  If I see something other than that pattern, it can tell me a lot about our stocking rate or other issues – not necessarily in a bad way.  There are also a few plant species that our cattle can’t seem to resist (some milkweeds, rosinweed, Canada milkvetch, and spiderworts) and we like to make sure those species get a release from grazing pressure every few years.  As a result, I pay special attention to whether or not – and how intensively – those plants are being grazed.  If I notice that they haven’t been allowed to grow and bloom for a few years, it’s time to change up our management and give them a rest.

The other group of plant species I look closely at is invasive species.  At our sites, invasive grasses such as smooth brome, Kentucky bluegrass, tall fescue, and others get special attention because of their ability to form monocultures, but there are plenty of others to watch as well.  I look not only at the current abundance and density of invasive plants, but also compare what I’m seeing to previous years to see how things are changing.  Finally, I pay attention to whether or not there are conditions that appear to be giving invaders an advantage.  For example, it would be important to know if cattle are grazing all the plants EXCEPT those invaders, allowing them to encroach upon weakened competition.

Siberian elm trees are a major pest in our prairies, and one we track closely and try to keep up with.
Siberian elm trees are a major pest in our prairies, and we have to be careful not to fall too far behind in our control efforts.

Field notes and photos are really helpful when trying to decide whether populations of invasive species are expanding or not.  They can also be helpful when comparing grazing impacts, responses from opportunistic plants, and other interesting phenomena.  I sometimes flip back to last year’s notes while I’m in the field to see if there’s anything I saw then that I should pay attention to.  Then, when I periodically enter my field notes into the computer, I can look at all the notes from other years and look for patterns.  I don’t take extensive field notes, but try to write enough to be useful.  (See here for more on field notes).

As I continue to learn more about the way various animal and invertebrate species see and utilize prairie habitat, I’ve gotten better at looking our prairies through the eyes of those species.  I wrote about wearing “bee goggles” a while ago, but I also try to step back and think about what life would be like in our prairies if I was a grasshopper, mouse, coyote, or other species.  Could I find food all year round?  Are there places to feed/hunt or hide/escape?  If the habitat I’m living in changed dramatically because of fire or grazing, would I be able to find and travel to other habitat nearby?  It’s a really interesting exercise, and helps me think about habitat needs in new ways.

Looking at a prairie through (cute!) eyes of bees or other species is a great way to broaden your perspective.
Looking at a prairie through the eyes of bees or other species is a great way to broaden your perspective.

Finally, I try to look across the fences and note what is happening on neighboring lands.  In some cases, the prairie I’m walking in is the only real prairie habitat in the neighborhood, so it really needs to provide everything for every species living in it.  In other cases, there is more grassland habitat nearby, and I can think about how our prairie can help supplement and complement what’s available in those other sites.  For example, if all the neighbors graze pretty intensively, I might prioritize tall vegetation structure a little more than if that was the predominant habitat in the neighborhood.

So there you go – a quick look inside my head, for what that’s worth.  As I said at the beginning, what you look for should be tied to your objectives, but I also enjoy tagging along when other prairie managers walk their sites because I learn a lot from how they think.  I’d love to hear how similar or different my thought processes are from yours.

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…

Why Are We Spending So Much Time Studying Birds?

Believe it or not, I really do like birds.

(And thus starts another blog post destined to draw the ire of my ornithologist friends…)

But here’s the thing.  I just read yet another study of grassland birds in which the researchers looked at the relative importance of variables such as habitat structure (tall, medium, and short grass, amount of shrub cover, etc.) and landscape composition (how much grassland is in the landscape).  It was a nicely designed study, but I found myself wondering how much value these kinds of studies are really adding to our ability to do effective grassland conservation.

A dickcissel sings from the top of a Woods' rose in restored Platte River prairie. Compared to most other kinds of animals and plants, we have a pretty solid understanding of the breeding habitat requirements of dickcissels and other grassland breeding birds.

Yes, we still have a lot to learn about grassland birds and their habitat requirements.  The more we learn, the better able to design conservation actions to help birds.  On the other hand, we already know an awful lot about grassland birds relative to other groups of grassland species like snakes, ground squirrels, grasshoppers, leafhoppers, fungi, and nematodes.

It’s kind of like we’re going to high school but only really studying in art class.  Art is important and enjoyable, but focusing only on art is not going to prepare us very well for dealing with the world.

If I was going to design a grassland landscape to maximize bird conservation, I think I could do a pretty good job based on what we know right now.  I’d start with multiple large blocks of prairie (hundreds of acres in size – much bigger, if possible).  Those blocks of prairie would need to include both upland and lowland grassland areas, and be floristically diverse enough to support an abundant supply of insects and seeds.  I’d include some scattered patches of shrubs and small trees in the landscape, but would place them so that there are still large areas of grassland with no woody vegetation at all.  Management would be important, and I would try to ensure that a variety of habitat structures was available each year, including the whole continuum between very short-cropped vegetation and tall dense and/or weedy cover.  It would be great to have those habitat types mixed together such that each block was a decent size (20 acres or more?) but that they were close enough together that birds species requiring more than one cover type during a season can easily move between them.  I’m sure those more up to speed on current literature might add a few tweaks to this landscape design, but I think this covers the more important components.

Sure, there are still a few holes in our knowledge of, especially in terms of their requirements for migratory habitat, but as a whole we’re in pretty good shape.  I would argue that our biggest limitation is not the ability to predict what birds need, but rather our ability to implement the necessary changes on the land.  However, that only applies to birds.  Does anyone feel they could similarly and accurately predict the landscape scale habitat needs of the smooth green snake, Franklin’s ground squirrel, or the long-jawed orbweaver spider? Not me.

A smooth green snake found in the Platte River Prairies, Nebraska. Very little is known about the habitat and/or landscape requirements of species like this one. We don't even really know much about how many there are. They are considered to be rare in most places, but we find them fairly regularly in our prairies - they're just really hard to see!

It would be different if we were confident that a landscape designed for birds would provide for the needs of all other prairie species.  I think we’re far from being able to say that.  Here’s just one reason I’m skeptical:  Grassland bird species are extremely mobile, and most migrate long distances between breeding seasons.  This allows those birds to find the best appropriate habitat (within reason) each year, even if that habitat isn’t where it was the previous breeding season.  Most other grassland species don’t have that kind of mobility, but many (most?) of them have fairly specific habitat structure requirements.  When the habitat structure where those species are living changes, how far can they travel to find appropriate habitat?  What kinds of terrain can they cross?  These are questions with huge implications for how we should be managing prairies and prairie landscapes, but we can’t do anything but make wild guesses because although we know how birds deal with those issues, we don’t know how most other species do.

I explored this issue of birds as indicators for the conservation needs of other species in an earlier post, if you’re interested in reading more.

Mice are fairly mobile species (compared to wingless invertebrates, for example) but we still know relatively little about their ability to find the kinds of habitat structure they need. When conditions change, do they travel long distances in search of appropriate habitat? Or do they just hunker down and wait for better times? If they travel, how far can they go, and what challenges do they face?

So why are we still spending so much time studying birds instead of branching out to other species and broader questions?  One big reason is inertia.  Scientists rightly like to build upon previous projects, so because there have already been a lot of studies of birds, there is a lot to build upon.  This makes sense in terms of efficiency (study methods are already designed and tested) and from the standpoint of funding availability (it’s often easier to sell a project that is builds upon what we already know than one that is reaching into the unknown).

A second reason we study birds so much is that they’re relatively easy to see, hear, and identify.  Since most research is done by graduate students and technicians, picking species that can be learned quickly is very helpful.  I should know – I did my own graduate research on grassland birds!  However, since then, I’ve learned that it’s not that hard to pick up on the sampling and identification skills needed to study other organisms, and that with invertebrate species, there are experts that can do the identification for you.

Of course, the biggest reason we study birds so much is that we LIKE birds so much.  If ground beetle watching was as popular as bird watching, prairie research and conservation efforts might look very different!  The irony, of course, is that we’re essentially focusing a very large proportion of our research and conservation effort on only a dozen or so grassland bird species (in any particular landscape).  At least if we were studying ground beetles, we’d be looking at several times that many species – and while I don’t know that much about ground beetles, I’ll bet they would be equally good indicators of the “health” of the prairie ecosystem.

A sedge wren on velvety gaura in the Platte River Prairies. Tiny birds, with cute little tails and aggressive personalities, sedge wrens are great examples of why birds are so compelling to people.

Look, I get it.  We’re not going to turn this battleship on a dime and move all the bird research funding and effort into smooth green snake and ground beetle research within a year or two.  However, I do think it would be really valuable for those doing bird research to incorporate broader community questions into their projects, whenever possible.  Maybe we could start by asking questions about how well birds really do represent the needs of other species?  Would funders of grassland bird research be open to that line of exploration?  It would allow us to build upon what we know about grassland birds by testing those known parameters on other taxa.  If we could figure out where the needs of birds and other species diverge, that’d be a great step forward in terms of defining future research needs.  Are great prairie chicken landscapes also great grasshopper landscapes, or not necessarily?  Do sedge wrens and massasaugas have similar habitat needs, or at least compatible habitat needs?  If not, how do we balance the needs of both species?  Let’s build on what we know about birds, but do it through some comparative analyses with other species.

Because you’ve got to admit – ground beetles are pretty cute too!

Ground beetles like this one (Pasimachus sp?) are abundant and diverse members of the prairie community. What do we know about their conservation needs? Not much.