Another Example of the Value of Thistles

Thistles are among the most disliked plants in the world. Sure, they’re spiny, and some species have become invasive after being transported outside their native range. But thistle flowers are gorgeous, provide incredible resources for pollinators, and their seeds are nutritious wildlife food. American goldfinches even nest a little later than many other songbirds just (apparently) so they can feed thistle seeds to their kids.

Two painted lady butterflies compete with a digger bee for the bounty found in a native tall thistle (Cirsium altissimum) flower.

So why do people hate thistles so much? Don’t tell me it’s because they’re spiny. The thorns of roses don’t seem to have hurt their popularity. In my neck of the prairie, a lot of people dislike our native thistles because they assume all thistles are invasive, or at least weeds. But even when they learn that species like Flodman’s or wavy-leaf thistles (Cirsium flodmanii and C. undulatum) are native, most people aren’t impressed.

A few years ago, I tried to get some momentum behind the idea that thistles are important for pollinators. That movement didn’t get far, despite it’s catchy (I thought) slogan. I still try to convince people they should be more open minded about thistles, but I don’t really have much hope of success. Despite that, I’m going to present one more piece of evidence on the side of thistle value. Stick with me – the story doesn’t start with thistles but I promise it’ll get there.

This past weekend, I spent two afternoons cutting eastern redcedar trees out of our prairie. For the most part, we catch and cut those trees while they’re still small enough to nip off with loppers. This weekend, though, I was working on the ones that had flown under the radar long enough to grow bigger than loppers can handle. As a result, I was using my noisy chainsaw to knock them down.

As I worked, I started noticing big clumps of grass and other material – mouse nests – embedded in the branches of a few trees. Some were at the bases of the small trees and others were a few feet up the trunk. All were empty, and it took me longer than it should to realize that they were probably vacant only because my noisy saw was scaring the inhabitants off before I got close. I felt bad about disturbing the nests but also really needed those trees to die before they started producing seeds and swarming over the whole prairie. I tried to keep the nests intact as I laid the trees down, hoping the little critters would move back in once I left.

As I neared one particular draw, I started finding a higher percentage of trees with nests in them, and the composition changed from mostly grass to mostly white fluff. Looking more closely, it was clear the fluff was from thistle seeds. I’m pretty sure most of the seeds came from a patch of bull thistles (Cirsium vulgare) I’ve been keeping track of. (Bull thistle doesn’t tend to be very invasive in our area, despite being non-native, so I’m pretty tolerant and just monitor them to make sure they aren’t going crazy.)

A mouse nest built from thistle seeds about three feet off the ground in a small eastern redcedar trees.

I don’t know if the higher abundance of nests in that area was due to the availability of thistle seeds – or even if they really were more abundant versus just being more visible because of their pale color. Regardless, they looked extremely cozy; the insulating value of thistle fluff has to be pretty incredible. Some of the nests were nearly the size of volleyballs and pretty hard to miss, even when obscured by branches full of dark green needles.

So, add one more attribute in the positive column for thistles – they provide great insulating material for winter shelters of mice. And don’t tell me you’re anti mouse and try to spoil my argument. Even if you don’t think mice are cute little critters, which they objectively are, the prairie ecosystem would fall apart without them. Among other things, they’re key food sources for many larger animals and important consumers/transporters of seeds.

Speaking of transporting seeds, the biggest mental image that sticks with me from seeing all those thistle seed nests is not the volleyball-sized masses of fluff. Instead, I’ve been obsessively thinking about those poor mice hauling all that fluff several feet up into those trees. First of all, that’s a tremendous amount of work – gathering the seeds from the tops of spiny plants, hauling it down the plants, across the prairie, and up into the trees. Over and over.

But they’re not carrying those seeds in their paws… they’ve got to be carrying them in their mouths! Imagine stuffing your mouth full of thistle seeds and then scurrying over the ground and up a tree before trying to spit all that stuff out again. Think about what it feels like to have a hair in your mouth and the sound and faces you make as you try to dislodge it. Now imagine the same sounds and faces on an adorable little mouse trying to spit out an entire mouthful of thistle fluff, which has to be far more worse than hair. This is the lasting imagery in my head, and I can’t tell whether I should be laughing or feeling regretful for screwing up the results of all that effort.

Tall thistle seeds. Nutritious, graceful, and not something you’d want to carry around in your mouth.

I really do feel badly about disturbing all those mice, though at least the weather was really nice as they sought shelter elsewhere. Hopefully, all the mice made their way back to those nests and didn’t mind that the host trees were now oriented horizontally instead of vertically. But while I feel bad about (temporarily?) dislodging them, and while I know it’s not nice of me at all, I’m even more distracted by what sound those mice must have made when they tried to spit out all those fluffy seeds…

‘Phleh! Phleh! Phleh!!’

Photos of the Week – February 21, 2020

We got a little more snow than expected Wednesday – maybe an inch and a half or so. Thursday morning was sunny and pretty calm, so I snuck out to Lincoln Creek Prairie for an hour before starting my official work day. It was a beautiful morning, but I had a really hard time finding photographic inspiration. Some days are like that. I know it’s the same for writing, and I imagine also for drawing, painting, and other creative arts I have no talent for.

I spent some time photographing shadows of grasses and wildflower leaves on the snow. That was kind of interesting, but the results weren’t particularly striking. I tried photographing the sun itself coming through prairie grasses, but nothing seemed to turn out well. Eventually, along the edge of the prairie, I came across a couple places where the grasses had etched patterns into the snow.

This was not from this week, but from a few years ago after strong winds caused grass leaves to spin around and create great patterns in the snow around them.

We didn’t get the kind of strong winds that often accompany snowfall, so I didn’t see the nearly or fully complete circles around grasses that I sometimes do (see above photo from a few years ago). Instead, there were very subtle scratches in the snow surface from leaves or seed heads that had been pushed back and forth by the wind. The combination of those small arcs with the straight line shadows of the leaves and stems gave me something to play with. Since my brain wasn’t being helpful with any other inspirations, I went with it.

As per usual, once I started seeing something, I saw it all around me, although only a few grasses created these patterns – the situation had to be just right. If a leaf or seed head was too low, it became embedded in snow and the wind wasn’t able to dislodge it. There were lots of others that were hanging just a bit above the snow and couldn’t quite reach it. Only a select number of plants were dangling part of themselves at the perfect height to barely touch the surface and be moved by the slight breeze. (Can you believe I made a whole blog post out of this?)

Even on days when I’m not feeling particularly inspired, a prairie walk in fresh snow is still a refreshing experience. Snow dampens all surrounding sounds, so even on the edge of town it was nearly silent except for the quiet crunching of my own footsteps. Fresh snow is usually a great opportunity to see evidence of wildlife activity, though yesterday was a poor example of that. I think the -1 Fahrenheit temperature might have been responsible a scarcity of animal tracks.

I’m glad I braved the cold (with no wind, it really wasn’t too bad). By noon, the sun and quickly warming temperatures had already melted much of the snow. That means no more grass leaf etchings until the next snow, and who knows when that will happen. Sandhill cranes are starting to invade the Platte River valley already, joining the hordes of geese and ducks already here. Spring is coming.