Hubbard Fellowship Post – Grasshopper Mice

This post was written by Jasmine Cutter, one of our Hubbard Fellows.  Jasmine has written earlier about her independent research project looking at small mammals (or s’mammals, as she calls them) in our Platte River Prairies.  All photos are by Jasmine unless otherwise credited.

S’mammal Spotlight: the Fearsome Northern Grasshopper Mouse

While I finish up the data entry for my independent project on small mammals, I thought it’d be fun to share some more information about some of the s’mammals out in our prairies. Some of them are really, especially awesome, and hopefully knowing a little more about them will elucidate why we think they’re worth studying!

The northern grasshopper mouse.  Note the big eyes and ears.

The northern grasshopper mouse.  See the note at the end of this post about how this photo was taken.

I thought I’d kick off this series with one of my favorites, the northern grasshopper mouse (Onychomys leucogaster). There is no other way to describe this critter except beefy. This is a mouse made for fighting, for pouncing, for striking fear in the hearts of the other lil s’mammals (I haven’t obtained any critter statements about the last part, but if I was pocket mouse-sized, I’d be wary). They are a handful to work with – very aggressive, and surprisingly agile. They’re able to shrink out of pretty much any corner I try to limit them to, and their pointy carnivorous teeth ensure that I am very aware of the distance between my fingers and their mouth!

If you’re wondering if you’ve seen one, northern grasshopper mice have big eyes, big ears, and relatively short tails that are consistently about 42 mm long (Mike and I measured many grasshopper mouse tails). The majority of them are silky gray-brown on top and white below, though there are a few whose backs are more cinnamon-y than gray. Juveniles tend to be lighter colored. Most of the grasshopper mice I caught were approximately the size of my fist, maybe a little smaller, about 33-45g (for reference, pocket mice are generally 8-12 grams).

cute lil grey guy. I would guess this one is on the younger side of things. Its fur has some of that downy, juvenile look to it. [good ones for the disclaimer? When I open a trap, I gently plop the critter into a bag in order to minimize handling exposure. I can weigh, identify and sex the critter while it’s in the bag. It’s safer for me, and the animal is only in there for a few seconds to a minute.

Cute lil grey guy. I would guess this one is on the younger side of things. Its fur has some of that downy, juvenile look to it. DISCLAIMER: When I open a trap, I gently plop the critter into a bag in order to minimize handling exposure. I can weigh, identify and sex the critter while it’s in the bag. It’s safer for me, and the animal is only in there for a few seconds to a minute.

This is one of more cinnamon-y colored ones.

This is one of more cinnamon-y colored ones.

The impressive muscle mass of a northern grasshopper mouse is achieved by a largely carnivorous diet. True to their name, grasshopper mice consume a lot of grasshoppers, as well as other insects, and sometimes other mice, including others of their species. Allegedly, grasshopper mice stalk their prey and will emit a shrill cry before attacking. It is thought that they tend to have a longer period of maternal care than most mice (which isn’t saying much) so that young grasshopper mice can be taught to hunt. Ideally, I’d like to camp out by their burrows in the spring so that I can hear them sing and see their fearsome predatory skills in action.

This is probably one of the youngest-looking grasshopper mice I found. It is fairly small, its fur is still more downy than silky, and its head/eyes to body ratio makes me think it's pretty young. Also it wasn't very good at being elusive or aggressive compared to most, so hopefully mom is still giving it some lessons! [The clip on its tail is attached to my mouse scale. While it is undoubtedly a little uncomfortable, there is no permanent damage. Using the clip means I am touching them less, and speeds up the photo taking process so they can be released faster!]  This is probably one of the youngest-looking grasshopper mice I found. It is fairly small, its fur is still more downy than silky, and its head/eyes to body ratio makes me think it's pretty young. Also it wasn't very good at being elusive or aggressive compared to most, so hopefully mom is still giving it some lessons! [The clip on its tail is attached to my mouse scale. While it is undoubtedly a little uncomfortable, there is no permanent damage. Using the clip means I am touching them less, and speeds up the photo taking process so they can be released faster!]

This is probably one of the youngest-looking grasshopper mice I found. It is fairly small, its fur is still more downy than silky, and its head/eyes to body ratio makes me think it’s pretty young. Also it wasn’t very good at being elusive or aggressive compared to most, so hopefully mom is still giving it some lessons! [The clip on its tail is attached to my mouse scale. While it is undoubtedly a little uncomfortable, there is no permanent damage. Using the clip means I am touching them less, and speeds up the photo taking process so they can be released faster!]

 

The underside of a grasshopper mouse. If you look closely, there's a faint orange circle on this one's chest, suggesting that I marked it on a previous week's transect.

The underside of a grasshopper mouse. If you look closely, there’s a faint orange circle on this one’s chest, suggesting that I marked it on a previous week’s transect.

If you’re looking for a northern grasshopper mouse, you are mostly likely to find them in sandy soils. They seem to prefer sandy areas that had sparser and often shorter vegetation. Apparently the sandhills portion of our Platte River Prairies are ideal habitat because they are loaded with northern grasshopper mice. It is exciting that we have such a robust population, especially because it gives us a chance to learn more about them.

The sandhills area of the Platte River Prairies - habitat of the northern grasshopper mouse.  Can you spot the flag marking a trap location?

The sandhills portion of the Platte River Prairies – habitat of the northern grasshopper mouse.

Learning more about their habits will not only aid in our management of our prairie, but could potentially help fill some gaps in the broader scientific literature. While the life histories of some small mammals are pretty well understood, it seems to me that there is some updating to do in terms of the natural history descriptions of northern grasshopper mice. For example, most natural history sources will tell you that the northern grasshopper mouse is very territorial and will fight to the death any other grasshopper mouse that wander into its territory. However, Mike and I have been catching several northern grasshopper mice within 10-14 meters of each other. This seems like a much higher density than one would expect for a highly territorial species, especially one that is known to have a fairly large home range in relation to its size.

Greg Wright, a wildlife biologist at the Crane Trust says he’s seen reports that grasshopper mice might hunt as family units, which could explain the densities we were catching. [It will be intriguing to see if our data supports that idea]. It could also be that northern grasshopper mice are only especially territorial during the mating season? A small study in Colorado found that several individuals shared a burrow in the winter.

I think these critters have a compelling story, and I look forward to our future studies and new research questions so that we can expand our understanding of the awesome, fierce northern grasshopper mouse.

BEHIND THE SCENES

Can you spot Chris' black camera? You may think that Chris spends a lot of time wander through prairies flipping over leaves, but really, the majority of his photos are staged in a cardboard box... This is a behind-the-scenes look at the photo assistant setup during our first field day, when Mike and I brought a grasshopper mouse to show people before we released it. Can you spot Chris' black camera? You may think that Chris spends a lot of time wander through prairies flipping over leaves, but really, the majority of his photos are staged in a cardboard box... This is a behind-the-scenes look at the photo assistant setup during our first field day, when Mike and I brought a grasshopper mouse to show people before we released it.

Can you spot Chris’ black camera? You may think that Chris spends a lot of time wandering through prairies flipping over leaves, but really, the majority of his photos are staged in a cardboard box… This is a behind-the-scenes look at his photo setup during our first field day, when Mike and I brought a grasshopper mouse to show people before we released it.  The result was the first photo used in this post.

Editor’s Note:  Ok, two things, gigglepants.  First, have YOU ever tried to take a photo of a grasshopper mouse in the wild?  Exactly.  They don’t tend to sit still and pose, do they?   Second, I have not hidden my photo techniques in the past, and on the rare occasion when I use something like a cardboard box to get a photo that would be otherwise impossible, I try to be transparent about it.  Many readers will remember my very serious technical piece on how to use a wheelbarrow as a photo studio, for example.  At least I don’t use something silly like a plastic bag…  : )

Jasmine’s favorite s’mammal information sources:

University of Michigan’s Museum of Zoology Animal Diversity Web. This site has photos, skeletons/skulls, life history information, range, and usually some tidbits from recent studies.   http://animaldiversity.ummz.umich.edu/

Mammals of Kansas
Clearly, most of the range information is specific to Kansas. But has good pictures, good descriptions (lengths, weights, color), and succinct life history information.
http://kufs.ku.edu/libres/Mammals_of_Kansas/list.html.

The Colorado paper I mentioned:
Size and Habitat Characteristics of Home Ranges of Northern Grasshopper Mice (Onychomys Leucogaster). Paul Stapp. The Southwestern Naturalist, Vol. 44, No. 1 (Mar., 1999), pp. 101-105

So Similar, Yet So Different

It’s wrong to assume that successful restoration or management tactics from one prairie will work in another.  Instead, every prairie has its own “personality” and responds accordingly.  The key to success is experimentation and adaptive management.

Bill Kleiman is one of my favorite people.  We have much in common: a love of prairies and restoration, a drive to learn from our mistakes and share what we learn with others, and a strong belief in the importance of conservation.  We’ve both worked for The Nature Conservancy for a long time (he’s got a couple years on me) and have been co-leading the Grassland Restoration Network for the last several years.  He’s also a great guy and a good friend.

Bill Kleiman (white hat) leads a tour of a restored prairie at The Nature Conservancy's Nachusa Grassland.

Bill Kleiman (light-colored hat) leads a tour of a restored prairie at The Nature Conservancy’s Nachusa Grasslands.  2014 Grassland Restoration Network workshop.

However, despite the fact that Bill and I are friends and have a lot in common, there are some big differences between us as well.  Bill is much more patient than I am, and better at the social niceties needed to build close relationships with neighbors and volunteers.  I tend to say what I think – sometimes inappropriately.  Bill is not shy about expressing his opinion, but does it less frequently, and usually with kindness and self-deprecation.

Bill and I both manage grasslands for The Nature Conservancy, but just as there are differences between us as people, there are also some stark differences between our sites and the approaches we take toward prairie restoration and management.  Bill’s site, TNC’s Nachusa Grasslands, is located in rolling hills about two hours west of Chicago, Illinois.  My Platte River Prairies are on mostly flat alluvial (river-formed) soils in south-central Nebraska.  As a result, the soils, topography and climate vary greatly between the two sites.  Moreover, our sites each have unique land use histories, invasive species legacies, and social and cultural contexts.

Bill again, talking to a tour group - with the Nachusa Grasslands in the background.

Bill again, talking to the same tour group, with Nachusa Grasslands’ undulating topography in the background.

I was thinking about all of this last month as our Platte River Prairies crew traveled to Nachusa Grasslands where Bill and his team were hosting this year’s annual Grassland Restoration Network workshop.  It was fascinating to compare the land management and restoration strategies we each use, especially knowing that both of us have diligently tested and refined our methods to meet the individual challenges of our respective sites.  Below are some of the similarities and differences between our approaches.

1. Seed Mixtures and Seeding Rates

Both Nachusa Grasslands and the Platte River Prairies have been actively restoring cropland to high-diversity prairie habitats.  At both sites we broadcast our seed (as opposed to drilling it).  The seed is broadcast either by hand or with a drop spreader – a fertilizer spreader that drops seeds onto the ground.  In fact, broadcast seeding is the technique of choice for the vast majority of sites that participate in the Grassland Restoration Network.  (You can learn more about fairly universal strategies and tactics in the “Lessons from the Grassland Restoration Network” document several of us put together.)

However, while we both broadcast seeds, Bill has found that successful prairie plantings at Nachusa require much heavier seeding rates (around 50 bulk pounds of seed per acre) than we use along the Platte River (8-10 bulk pounds).  Bill’s seed mixes include lots of seed from wildflowers, sedges, and “subdominant” grasses such as little bluestem, prairie dropseed, and sideoats grama, but almost no seed from more dominant grasses such as big bluestem and indiangrass.  In our Platte River Prairies seed mixtures, dominant grasses make up about half of the weight of the mixture.

James Trager (Shaw Nature Reserve) and Nelson Winkel (TNC Platte River Prairies) look over a restored prairie at Nachusa Grasslands.  This prairie was relatively unique in that it had a fair amount of indiangrass in it.  Most of the seed mixtures have none, or very little, seed from big grasses such as indiangrass and big bluestem.

James Trager (Shaw Nature Reserve) and Nelson Winkel (TNC Platte River Prairies) look over a restored prairie at Nachusa Grasslands. This prairie was relatively unique in that it had a fair amount of indiangrass in it. Most of the seed mixtures have none, or very little, seed from big grasses such as indiangrass and big bluestem.

Both Bill and I have experimented with many variations of these seed mixtures and have settled on these broad recipes as appropriate for our respective sites.  Though we do things differently, we both end up with very diverse prairies that meet our objectives.  When Bill uses lighter seeding rates, his new prairies get swamped out by invasive species before native plants become well established.  He’s also found that adding dominant grasses to the initial seed mix leads to plant communities that become overly grassy and not very diverse.  In contrast, using lighter seeding rates on the Platte allows us to plant more acres per year with the same seed harvest effort, and while it takes longer for our plantings to establish, they still end up being very diverse.  As our plantings mature, fire and grazing management helps suppress the dominance of big bluestem and indiangrass and maintain high plant diversity.

2.  Weed Control in New Restored Prairies

Weed control strategies for new plantings also vary greatly between Nachusa Grasslands and the Platte River Prairies.  At Nachusa, Bill and his crew walk every inch of new plantings multiple times each year until the native plant community is well established.  They remove (by pulling or spraying) every invasive plant they find – focusing mostly on perennial legumes such as birds foot trefoil, crown vetch, and sweet clover.  Once the native community is established, they can relax a little, but they still watch each site very closely.  In some cases, they’ve not been able to keep up with the pressure from invasive plants and they’ve made the difficult decision to just give up and start over, rather than fighting a losing battle for years.

The soybean field on the left is a former restored prairie that just never established as Bill hoped, so he and his crew made the decision to start over.  After it is farmed for a few years, they'll try again.

The soybean field on the left is a former restored prairie at Nachusa Grasslands that never established as Bill hoped, so he and his crew made the decision to start over. After it is farmed for a few years, they’ll try again.  While it’s a lot of work to start over, it’s less work than many years of fighting weeds and never winning.

Our weed control on the Platte River Prairies looks much different.  We don’t really have problems with perennial legumes or other non-native forbs.  In fact, we pretty much ignore sweet clover, and most other “weeds” during the establishment phase of a new prairie are annuals such as foxtail, marestail, and annual sunflower that just fade away as perennial prairie plants take over.  Our major fears have to do with perennial invasive grasses, such as smooth brome and Kentucky bluegrass, and we deal with those mainly by suppressing them with fire and grazing management.  We also worry about deciduous trees, such as Siberian elms, that we have to control with herbicides because fire and grazing don’t do the job.  However, during the first few years of establishment, while Bill and his crew are painstakingly patrolling their sites, we can mostly ignore our new plantings – except for an occasional prescribed burn to limit the buildup of thatch.

3. Overseeding

A third difference between our sites has to do with overseeding.  In both remnant (never plowed) and restored prairies, we occasionally want to add missing plant species.  At Nachusa, they just burn the prairie and throw the seed out on the bare ground – and it works!  In our drier Platte River Prairies, we’ve not had very much luck with that strategy.  Using grazing to weaken the dominant grasses seems to help us get better establishment of new plants because it suppresses competition for moisture and other resources.  Bill’s crew doesn’t seem to have to worry about that – even in sites with lots of grass.

Bill (left) oversees some "data collection" during this year's Grassland Restoration Network, which was done to help tour participants evaluate an overseeding project.  Becky and Hank Hartman (volunteer stewards) have used repeated overseeding to transform an area from exclusively grasses to one with very nice wildflower diversity.

Bill (left) oversees some “data collection” during this year’s Grassland Restoration Network, which was done to help tour participants evaluate an overseeding project. Becky and Hank Hartman (volunteer stewards) have used repeated overseeding to transform an area from exclusively grasses to one with very nice wildflower diversity.

 

Mike Konen (in orange) from Northern Illinois University talks about soils during this year's workshop at Nachusa.  He is standing in prairie that is going to be grazed by the newly introduced herd of bison.  Grazing will give Bill and I one more thing to compare notes on...

Mike Konen (in orange) from Northern Illinois University talks about soils during this year’s workshop at Nachusa. He is standing in prairie that is going to be grazed by a newly-introduced herd of bison (the bison should knock the height of that indiangrass down some…) Now that Nachusa is using grazing  as a management too, Bill and I will have one more thing to compare notes on…

Bill and I have done extensive experimentation to come up with effective prairie restoration and management strategies at our respective sites, and we continue to adapt as we go along.  We can learn from each others’ experiences, but there is also much that doesn’t translate well between sites.  Some of that is due to the distance between Nachusa and the Platte, and the corresponding differences in climate and soils.  However, even prairies that are much closer together can respond very differently to management and restoration tactics.  Soil types, seed banks, topography, management history, landscape context, and many other factors combine to give every prairie it’s own “personality”.

It might seem overwhelming to learn that every prairie requires a unique set of restoration and management strategies, but it’s really not that bad.  There are a still a lot of commonalities between prairies – just like there are many similarities between Bill and me.  However, just as you would need to consider differences between Bill’s personality and mine in terms if you wanted a positive response from us, the same holds with prairies.  (If you want a favor from Bill, you might want to invite him to a little gathering and serve good beer.  On the flip side, if you want something from me, pizza would make a better bribe, and while I’m not against parties, the less small talk needed, the better…)

Above all, beware of anyone who tells you’ve they’ve figured out the magic formula for how to manage or restore prairies.  It’s just not possible.  Instead, take a look at what others do, learn from their experiences, and then experiment with a variety of techniques at your own site.  It won’t take long to figure out what moves your prairie in the direction you want.   Fortunately, unlike Bill (I’m kidding!) prairies are pretty forgiving, so if you try something and it doesn’t work, they aren’t likely to hold a grudge.

P.S. Bill will be appalled that I’m giving him so much credit for the work at Nachusa.  Clearly, both Bill and I have crews of staff and volunteers that do most of the work and much of the thinking.  For this post, however, I was trying to build an illustration of personalities in people and personalities in prairies.  It was a lot easier to do that by focusing just on Bill and me.  Please understand that the ideas and work of Nelson, Cody, Mardell, Hank, Becky, Karen, Al, Bernie, Jay, Susan, Leah, and many others are represented here as well.  (There, does that make you happier Bill?)