The berries of eastern redcedar (Juniperus virginiana) provide a significant source of nourishment for black-capped chickadees in winter.
"Eat food. Not too much. Mostly plants." --Michael Pollan
Eastern redcedar, Juniperus virginiana, is a common native conifer (Latin for "cone-bearing") in northeastern Iowa. Though there's actually more than one species of Juniperus here, many of us locals refer to this one simply as "cedar," as I will from now on. Driving through our Driftless area, you may see it dotting old pastures, or clustering on steep, rocky slopes, where, in many cases, it has replaced native prairie grasses and wildflowers. Here it is as I encountered it on Sunday at the Pulpit Rock overlook, part of the City of Decorah's Will Baker Park.
Being a conifer, cedar produces cones. Have you seen them? While on my walk, I overheard an observant young girl on the trail behind me exclaim to her family, "I found a blueberry!" That's not a bad description for a cedar tree's seed cone; here's several on a bough:
When you think about it, it's fascinating that junipers, despite being quite unrelated to the flowering plants that produce "true" berries, would evolve such a berry-like form for their seed cones. Whom can you think of who would appreciate this evolutionary quirk? What kinds of critters like berries?
If you're a bird brain like me, our feathered pals come to mind. Certainly cedar waxwings appreciate these nutritious offerings from their namesake tree; perhaps you've seen these elegant birds hanging out together in a juniper, tumbling, stretching, gulping down "cedar berries" by the beakful. And usually...at least from what I remember...they pluck the berries from the tree and swallow them whole. So, at Will Baker park, when I found cedar berries still attached to the tree, but with their seeds mysteriously gone, I doubted that cedar waxwings were responsible.
I can't say for sure who did this; can you? I do have a guess, though (we're getting there).
Under another cedar along the trail, the snow is strewn with debris. (I added that elm leaf for scale.)
If you find a cedar tree with berries, and look in the snow beneath it, you just may find seed pieces like this. The outer layer of the seed hasn't been pulverized; and it doesn't look to me like it's been chewed open, either. Here's a bunch more, which I'd gathered a few days before, in the snow beneath a couple cedar trees at Van Peenan park:
Who knows where the bird found that at this time of year?
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I've witnessed chickadees feeding on cedar seeds during winter in a few different places around Decorah, consistently enough for me to believe "it's a thing" - that is, it's a significant and regular food source for some of them. The sheer quantity of berry litter under cedar trees, however -- and that finding of cedar berries still on the tree but with their seeds removed -- leads me to wonder if other birds, or even mammals, might be feeding on the seeds' contents. After all, it's not just chickadees that crack open those black oil sunflower seeds from our bird feeders to get to the meat inside! Can you find evidence of any other creatures feeding on cedar seeds?
It's not really what I had in mind when I asked that question, but there is at least one animal around here that eats these seeds in a totally different way...instead of getting at them from the outside, it consumes them from the inside. Hint: it's very small!
If you know me, you probably know I've spent a lot of time over the past couple of years collecting live insects in the Decorah area, rearing them to adulthood, and posting my findings to a crowd-sourced invertebrate natural history website, Bugguide.net. An enduring mystery from my studies has been the question of which insect feeds inside cedar seeds and leaves tiny exit holes in the berries when it emerges:
You can click the image to go to my Bugguide page for this mystery, and scroll down for clickable thumbnails that tell more of the story. All I'll say here is that, while the culprit is a mystery (so far), I have reared more than one species of tiny non-stinging wasp from cedar berries (we're talking TINY, a small fraction of the size of one berry). These wasps are apparently parasites (the technical term is parasitoid) of the unknown insect that makes the holes in the berries. Here's one of the wasps, many times magnified. As you can see, it's a colorful animal:
And how about that teardrop-shaped eye?
I'll leave you with an image reminding us of the very smallness of all this:
The palm of my hand dwarfs a couple dozen discarded cedar berry "skins" from under those Van Peenan trees. But between the cedar waxwings, black-capped chickadees, teensy parasitoid wasps (we'll say 2 species of them for now), and the unknown hole-driller, I count five species of wild animals who feed on or live inside cedar berries! If we count humans, too, which we should -- take a gander at this webpage, for instance -- that makes six. And surely there are more.
This is the part where I lose words to describe why understanding things like this is important to me. I suppose it's because knowledge like this feeds a certain kind of love or deep respect for my fellow animals, which inspires me to pursue further understanding of them -- and so the heart and mind feed one another, back and forth, leading naturalists like me deeper and deeper into the mysteries of life. The next time you find a cedar tree laden with berries, I hope you too will pause to consider how important these little round cones can be. And if you find any signs of animals feeding on them -- or would like to share the ways you've used cedar berries yourself -- I'd love to hear about it!
"Eat food. Not too much. Mostly plants." --Michael Pollan
Eastern redcedar, Juniperus virginiana, is a common native conifer (Latin for "cone-bearing") in northeastern Iowa. Though there's actually more than one species of Juniperus here, many of us locals refer to this one simply as "cedar," as I will from now on. Driving through our Driftless area, you may see it dotting old pastures, or clustering on steep, rocky slopes, where, in many cases, it has replaced native prairie grasses and wildflowers. Here it is as I encountered it on Sunday at the Pulpit Rock overlook, part of the City of Decorah's Will Baker Park.
Yes, those are cones...botanically speaking. Produced only by female trees, each one contains a few seeds with a surprisingly thick, hard outer layer surrounding the meaty stuff inside.
That second image is a seed cut in half hot dog style, on my finger for scale; the third image shows a close-up of another seed cut open similarly.
If you're a bird brain like me, our feathered pals come to mind. Certainly cedar waxwings appreciate these nutritious offerings from their namesake tree; perhaps you've seen these elegant birds hanging out together in a juniper, tumbling, stretching, gulping down "cedar berries" by the beakful. And usually...at least from what I remember...they pluck the berries from the tree and swallow them whole. So, at Will Baker park, when I found cedar berries still attached to the tree, but with their seeds mysteriously gone, I doubted that cedar waxwings were responsible.
I can't say for sure who did this; can you? I do have a guess, though (we're getting there).
Under another cedar along the trail, the snow is strewn with debris. (I added that elm leaf for scale.)
Nearly all of the little particles you see atop the snow here are bits of torn-up cedar berries. There are pieces of the berries' fleshy outer layers here, and pieces of the seeds. That's right -- pieces of the seeds:
Now, I'm not going to rule out a rodent or some other unidentified creature, but I believe most, if not all, of these seeds have been broken open...by birds. And in particular, by black-capped chickadees.
In fact, just before I spent fifteen minutes on my belly collecting these seed pieces, I had watched a small group of chickadees in the cedars directly overhead, practicing their craft. A chickadee would pluck a cedar berry from the tip of a bough, then fly deeper into the tree, where it would find a nice hard twig or branch to perch on. Then it would hammer away at its prize, with its woody perch as the mortar, and its bill the pestle, if you will. And I do mean hammer -- I've seldom seen these birds put such force into breaking open anything. If you though that outer layer was the hardness of, say, the mere candy coating on an M&M, think again. I challenge any human to break open a cedar seed with their fingernails. Not gonna happen!
Inside the seed is the meaty stuff, the good stuff, the...what do you call it?
Since my botany education is failing me, let's ask George Francis Atkinson! Dr. Atkinson published his textbook Botany for High Schoolers in 1912, and on page 214 of that text, he wrote, "The cedar "berries," for example, are fleshy and contain several seeds. But the fleshy part of the fruit is formed, not from pericarp, since there is no pericarp, but from the outer portion of the ovule, while the inner portion of the ovule forms the hard stone surrounding the endosperm and embryo." (emphasis added)
So that's what the chickadee is after: the tasty endosperm and embryo of the cedar seeds.
As you can imagine, the chickadee's work creates a mess; along with all those seed pieces on the snow under the cedars, I found the fleshy outer parts of the berries, their seeds removed:
In this instance, the bird didn't even bother to remove the last seed from the berry before breaking into the seed:
I even found a dead wasp (family Vespidae) in the snow with the cedar berry litter, its head contents apparently pecked out.
Who knows where the bird found that at this time of year?
---
I've witnessed chickadees feeding on cedar seeds during winter in a few different places around Decorah, consistently enough for me to believe "it's a thing" - that is, it's a significant and regular food source for some of them. The sheer quantity of berry litter under cedar trees, however -- and that finding of cedar berries still on the tree but with their seeds removed -- leads me to wonder if other birds, or even mammals, might be feeding on the seeds' contents. After all, it's not just chickadees that crack open those black oil sunflower seeds from our bird feeders to get to the meat inside! Can you find evidence of any other creatures feeding on cedar seeds?
It's not really what I had in mind when I asked that question, but there is at least one animal around here that eats these seeds in a totally different way...instead of getting at them from the outside, it consumes them from the inside. Hint: it's very small!
If you know me, you probably know I've spent a lot of time over the past couple of years collecting live insects in the Decorah area, rearing them to adulthood, and posting my findings to a crowd-sourced invertebrate natural history website, Bugguide.net. An enduring mystery from my studies has been the question of which insect feeds inside cedar seeds and leaves tiny exit holes in the berries when it emerges:
You can click the image to go to my Bugguide page for this mystery, and scroll down for clickable thumbnails that tell more of the story. All I'll say here is that, while the culprit is a mystery (so far), I have reared more than one species of tiny non-stinging wasp from cedar berries (we're talking TINY, a small fraction of the size of one berry). These wasps are apparently parasites (the technical term is parasitoid) of the unknown insect that makes the holes in the berries. Here's one of the wasps, many times magnified. As you can see, it's a colorful animal:
And how about that teardrop-shaped eye?
I'll leave you with an image reminding us of the very smallness of all this:
The palm of my hand dwarfs a couple dozen discarded cedar berry "skins" from under those Van Peenan trees. But between the cedar waxwings, black-capped chickadees, teensy parasitoid wasps (we'll say 2 species of them for now), and the unknown hole-driller, I count five species of wild animals who feed on or live inside cedar berries! If we count humans, too, which we should -- take a gander at this webpage, for instance -- that makes six. And surely there are more.
This is the part where I lose words to describe why understanding things like this is important to me. I suppose it's because knowledge like this feeds a certain kind of love or deep respect for my fellow animals, which inspires me to pursue further understanding of them -- and so the heart and mind feed one another, back and forth, leading naturalists like me deeper and deeper into the mysteries of life. The next time you find a cedar tree laden with berries, I hope you too will pause to consider how important these little round cones can be. And if you find any signs of animals feeding on them -- or would like to share the ways you've used cedar berries yourself -- I'd love to hear about it!
