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

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About Chris Helzer

Chris Helzer is the Director of Science for The Nature Conservancy in Nebraska. His main role is to evaluate and capture lessons from the Conservancy’s land management and restoration work and then share those lessons with other landowners – both private and public. In addition, Chris works to raise awareness about the importance of prairies and their conservation through his writing, photography, and presentations to various groups. Chris is also the author of "The Ecology and Management of Prairies in the Central United States", published by the University of Iowa Press. He lives in Aurora, Nebraska with his wife Kim and their children.
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17 Responses to Hubbard Fellowship Post – Grasshopper Mice

  1. Matt BS says:

    When I worked on a small mammal project we put a layer of duct tape on the clip of the scale so it wouldn’t cut their tail. It still held them firmly. Might be worth trying even if you aren’t seeing any obvious injury.

  2. Ernest Ochsner says:

    OK you two behave or else.
    Great article, wonder how these guys would fare with the shrews I have around the library here in Aurora?

    • Jasmine says:

      Not that I condone animal fights, but a shrew vs grasshopper mouse showdown would probably be pretty epic. Both critters are pretty smelly, even to a human, so I imagine they probably have plenty of warning to avoid each other. Also, shrews tend to prefer thatchy, dense areas, whereas grasshopper mice prefer more open areas, although there is some overlap. I think the shrew’s venomous saliva would probably give it an advantage.

  3. I will never understand how some people ( I’m embarrassed to say women) are afraid of mice; any kind of mice. All s’mammals are cute critters, but mice enchantanly so. (Perhaps I watched “Cinderella” too many times?) Thanks for posting the pics and sharing the info.

  4. Karen Hamburger says:

    gigglepants????? :)

    Karen

  5. Jasmine says:

    woah, woah, woah. I believe I DID manage to take an excellent shot of a ghop mouse in the wild. No box. No tail clip. Nothing else sneaky.

  6. Inger Lamb says:

    Thanks Jasmine – cool info, great enthusiasm too. Looking forward to the rest of the series.

  7. The Birding Bunch says:

    Very interesting article and great pictures. I was curious as is one of the children… why the cotton balls?

    We have plenty of mice in our little prairie-to-be, but we have clay soil, so probably none of these fellows. I happen to enjoy all kinds of critters, but cannot convince my husband that spiders are ok. :)

    • Jasmine says:

      The cotton balls are so that the critters have nesting material when the weather is cooler. It helps them stay warm and dry. Normally, if it’s cooler than 40ºF I won’t trap because I’d be worried that the critters wouldn’t be able to survive the night in the trap. I’m sure some people trap throughout the year, they just check traps more frequently.

      I’ve been petitioning Dillon to rename our house SpiderHaven. They help with the flies, so I don’t have a problem with them, although I’m less excited when they pop out from under my pillow…

  8. anastaciast says:

    I am enjoying your posts immensely! If not for this migraine, I would wax eloquently on the content, excellence of photographs and jealousy of Chris. :)

  9. randomtruth says:

    Great post. I’ve been hoping to catch Onychomys here in CA on my camera traps in Mono County, but no luck yet.

  10. Laura Hughes says:

    Great post, Jasmine! I love grasshopper mice! This might be a dumb question but what do you bait your traps with to get grasshopper mice since they are carnivores? Thanks!

    • Jasmine says:

      That’s a great question! It’s actually kinda funny because Mike and I use a mix of oats and birdseed (millet, thistle) to bait – no meaty bait at all! That mixture does attract crickets and beetles (and slugs). I honestly don’t know enough about northern grasshopper mouse dietary preference to know if that’s enough to entice them into the trap, or if they’re just curious and investigating (which is true of shrews and probably many of the mice). Potentially, they could be pursuing a smaller mouse, but none of their scat in the trap has had bones or fur… Grasshopper mice are also ~90% carnivorous, so a nice pile of seeds may be just fine for a night. There were a fair number of recaptures, too, so clearly they were satisfied with what they found.

      That’s long answer to a short question. If I was specifically baiting for just grasshopper mice, I might consider baiting with crickets or mealworms, but I’m also not sure if it’d be so great for the prairie if those escaped. Even the seeds are tricky, I started microwaving my bait when I realized some of it was sprouting when it got wet! The mice didn’t seem to care.

  11. Pingback: Hubbard Fellowship Blog – Plains Pocket Mouse | The Prairie Ecologist

  12. Jen says:

    I am interested in camping in a location where I would have a relatively high probability of hearing the mouse howling (I have no ideas of grandiose concerning in seeing the mouse). Do you have any insight on locations where this might be possible? Perhaps back country desert locations (but which one…)? All information I have seen about habitat range is too broad for me to narrow down somewhere that seems like something more than just a shot in the dark. If you have any suggestions it would be appreciated. Thanks

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