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!
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).
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.
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.
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
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.
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
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.
Thanks for the tip! That’s a great idea! I will try it out next time we trap.
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?
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.
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.
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.
Thanks Jasmine – cool info, great enthusiasm too. Looking forward to the rest of the series.
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. :)
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…
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. :)
Great post. I’ve been hoping to catch Onychomys here in CA on my camera traps in Mono County, but no luck yet.
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!
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.
Thank you very much for your response! Very interesting!
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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