Photo of the Week – May 26, 2017

Shell leaf penstemon (Penstemon grandiflorus) is one of the showier wildflowers in the Platte River Prairies during late May and early June.  It is most often found in dry soils and where the surrounding plants aren’t overly competitive.  We often see populations increase after droughts and grazing events and then decrease again as grasses recover their vigor in subsequent years.

Shell leaf penstemon has big showy flowers that are just the right size for bumblebees, but are used by other pollinators as well.

For years now, I’ve been periodically coming across patches of shell leaf penstemon plants that have been decapitated by a rabbit or something.  That wouldn’t be surprising except that the top of the plant is usually just lying next to the plant uneaten!  There is a single angular slice in the flowering stem, usually well below the bottom-most flower, and the entire flowering stem just (apparently) falls to the side.  I’m at a loss to explain this.  I don’t know if an animal is doing this to lick the juices out of the stem for some reason?  I honestly can’t think of any other good reason for what I’m finding – not that juice licking is a very good reason…  I’d love to hear from someone who knows the answer to this.

Yesterday, Nelson (our land manager) and I were touring a colleague from Wisconsin around one of our prairies and found a patch of decapitated penstemon.  As we were discussing the mystery, Nelson grabbed one of the stems and saw what he thought might be a black stem-boring insect.  As we peeled apart the stem to see it, it turned out to be a small black wasp or bee that Nelson had apparently squished when he picked up the stem.  Before I could get a very good look, the wind blew the deceased insect off the stem and down into the grass at our feet.  I didn’t worry too much about it, but as we continued to peel open the stem, I wished I’d tried to recover the insect.

Here is the detached flowering stem Nelson picked up.

The penstemon stem was stuffed full of flies.  Flies of all shapes and colors.  There were more than 20 of them, separated intermittently by wads of dried plant material.  Based on what we found, I guessed the insect we saw, and then lost, must have been a wasp and that it was laying eggs in the stem and provisioning them with flies.  I took the stem home to photograph it and then sent the photos to my friend Mike Arduser, who knows everything about bees, and an awful lot about wasps and other insects as well.

Here is a close-up photo showing the diversity and abundance of the flies jammed into the stem. I looked, but didn’t see the eggs that must have been there.

Mike said the insect was very likely a wasp in the genus Ectemnius that usually uses flies as the food source for its larvae.  They frequently excavate the pith out of twigs and other stems.  Based on the behavior of other wasps, I assume the flies were paralyzed, not dead, and that there was an egg laid with them, but I didn’t actually see any eggs.  According to Mike, Ectemnius wasps have a kind of “cuboidal” shaped head and the various species are between 6 and 14 mm in size.

I’m very certain the wasp wasn’t responsible for cutting the flowering stem off the penstemon, but it was pretty interesting to see something taking advantage of the destruction.  I didn’t see any other stems with similar nests in them, but I’ll sure keep an eye out for that in the future…

Now if I can just figure out who or what is decapitating our penstemon plants, I’ll be satisfied.  Until the next mystery comes along.

PLANT GAME RESULTS:

On the whole, you did pretty well on the plant game this week.  I tricked most of you on the first one, but the majority of you guessed correctly on the second and third questions.

On the first question, 161 people voted (as of this afternoon) and almost 50% chose Candy Lovegrass as the fake name, which is wrong – it’s a real plant.  Look it up if you like.  The actual fake name in that list was Clark’s Blisterpod, which came in 3rd at 22%.

More people (212) were bold enough to guess on the second question, and 50% of you were correct that Bully Pulpit was the fake plant.  However, about 1/3 of you guessed Beefsteak Plant, which sounds fake but is real – and invasive in at least some places/situations.

On the third question, 172 people voted, and 47% correctly identified Slipper Cherba as a fake plant name.  Autumnal Water Starwort and Beaked Ditchgrass were second and third in the voting with 25% and 21%, respectively.  I really thought more people would go for Beaked Ditchgrass, but what do I know?

Thanks for playing my goofy game.  The hardest part of putting it together is coming up with names that are weirder than the real ones…

Posted in Prairie Animals, Prairie Insects, Prairie Natural History, Prairie Photography | Tagged , , , , , , | 4 Comments

Plant Game! (May 23, 2017)

The rules are simple.  Just pick the fake plant name from each list.  Three of the names in each list are official names of plants found in Nebraska.  The other is one that I made up.  See if you can guess the fake plant name.  Good luck!  I’ll post the answers in a day or two.

Bonus plant quiz. What is the name of this plant I photographed over the weekend at our family prairie? Choices: A) Starry milkvetch, B) Lambert’s crazyweed, C) Coryambula Fig, D) Higg’s Bow Sun

 

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Photo of the Week – May 19, 2017

Over the last five years or so, I’ve been learning a lot more about pollinators, and that has changed the way I look at prairies.  As I walk around our prairies, I often think about how I would see the site if I was a bee trying to find enough nectar and pollen to both survive and provision my eggs.  Often, our prairies are full of flowers, but April and May can be pretty tough months.  The flowers that are blooming tend to be small and scattered, and I can walk a lot of steps without finding anything.

Prairie ragwort (Packera plattensis) was a welcome sight for this orange sulphur butterfly after its northward migration this spring.

The lack of available flowers in the spring is not necessarily a new thing.  Spring weather is unpredictable, and investing resources in blooming early means risking a late freeze or (in some cases) flooding rains that can scuttle the whole process.  However, many prairies today have fewer spring flowers than they used to, and restored prairies (crop fields converted back to prairie vegetation) are often low on spring flowers because finding seed for those species is difficult.  Flowering shrubs can help make up for a scarcity of spring wildflowers, but they are also less common these days than they used to be.

Shrubs like this wild plum (Prunus americana) can provide critically important pollinator resources when few wildflowers are blooming. This photo was taken back in mid-April.

Prairie managers and gardeners can both play important roles in helping to provide spring flowers for pollinators.  In prairies, allowing shrubs to grow in some areas of the landscape can benefit pollinators in the spring, but also help out increasingly rare shrub-nesting birds during the summer.  Thinking about spring flower availability might also help inform prairie management plans, and enhancing restored, or even remnant prairies, to add missing spring wildflowers might be beneficial as well.  For gardeners, adding native spring wildflowers can be both aesthetically pleasing and extremely important for the bees and other pollinators in your neighborhood.

By the time this monarch emerges as an adult in a few weeks, there should be plenty of wildflowers available for it. Hopefully, it will be competing for nectar against a number of bees and other pollinators that made it through a tough spring season.

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The Joy, Angst, Excitement and Dread of Walking Through a Young Restored Prairie

Anyone who has watched a prairie seeding go through its first several years of establishment will appreciate and identify with this post.  For those of you who haven’t, the best analogy I can come up with is that the experience is a little like watching your son or daughter go off into the world on their own.  You can spend tremendous energy planning ahead, preparing a site, and harvesting and planting seed, but at some point, you have to just stand back and let the new prairie stand or fall on its own.  Sure, you can jump in and knock back the weeds a little now and then, but eventual success or failure depends upon many factors beyond your control, and it can be hard to predict the result during the first few years.

In February and March of 2016, we planted about 60 acres of land with a seed mixture of around 140 prairie and wetland plant species.  The site had been cropland for many years, and then was converted to a mixture of native grasses and used as pasture.  Eventually, the site became heavily invaded with tall fescue, smooth brome, and Kentucky bluegrass.  A few years ago, we decided to kill off the existing vegetation and try to establish a much more diverse plant community.  Although it had been farmed, the site still had some remnant wetland swales that had been farmed through and partially filled, but still had some wetland hydrology.  Restoring this 60 acres feeds into our larger restoration objectives of enlarging and reconnecting remnant (unplowed) prairies in the area.

Volunteers hand broadcast wetland seed on frozen wetlands during February 2016.

This “drop spreader” was used to plant the majority of the site.

We used a combination of herbicide application and tillage to get rid of the grasses and prepare a seed bed.  In addition, (under the appropriate permits) we had a contractor with a big scraper come in and deepen/widen the degraded wetland swales.  Using seed we harvested from nearby prairies and wetlands, a couple different groups of volunteers hand-planted the wetland swales and low sandy ridges created by excavation spoil, and we used a broadcast seeder behind a UTV to plant the remainder of the site.  (Thank you to the U.S. Fish and Wildlife Service, Nebraska Natural Legacy Project, and Nebraska Environmental Trust for funding this project.)

During the 2016 growing season, I visited the site very rarely, and didn’t spend much time there when I did.  Early in the season, there wasn’t much germinating and growing except the kinds of “weeds” you’d see in an abandoned crop field (foxtails, pigweeds, ragweeds, annual sunflowers, etc.).  Later in the season, those weedy plants had grown so tall and thick, it was physically difficult to walk through them.

This photo shows the kind of weed cover that grew during the first growing season. Lots of tall ragweed and annual sunflowers were joined by some perennial sunflowers and other plant species we had seeded.  This is pretty typical of what we see during the first year of our restored prairies.

I walked around this site on Monday of this week and tried to capture what I saw with my camera.  As I explored, I experienced a roller coaster of emotions.  Some areas are looking way ahead of schedule, with a nice diversity of prairie and wetland plants coming in, while others don’t look like they’ve even started, or have problematic plants that we might eventually have to deal with.  On the whole, I feel good about the progress of the restoration, though we do have some trees to control, but my overall confidence comes mainly because I’ve been through this process many times.  We’ve had restored prairies look like junk for 4 or 5 years before finally kicking into gear, and others that look like a prairie after two years.  Very rarely have we seen plantings fail.  Regardless, it’s way too early to guess how this planting will turn out.

For what it’s worth, here is what I saw and thought about during my walk around this prairie at the beginning of its second field season.

The first thing I saw as I walked into the new prairie was a pretty good sized patch of 3-4 foot tall cottonwood trees (Populus deltoides).  The parent trees can be seen in the background.  We’ve been getting smarter about removing those kinds of seed  sources before starting projects, but these trees are growing along a public road and we didn’t have the authority to remove them.  We’ll have to evaluate our options for controlling the young cottonwoods in our new prairie.

A skeleton of an annual sunflower from the initial season shows how big some of those pioneering species were last year. Many of the sunflowers were over 12 feet tall.

Biennial wildflowers, like this prairie ragwort (Packera plattensis) germinated last year and are blooming this year. Hopefully, this one will start a colony that will help support spring-flying bees and other pollinators in future years.  A pair of crane flies are mating on top of this one.

I was excited to see quite a few sedges blooming in only their second year. We don’t always get quick establishment of sedges from seeds. This one (Carex craweii) was in a patch of maybe 10 plants along the edge of a wetland, and I found at least three other species growing elsewhere in the site.

To balance out the excitement of seeing lots of sedges, I also found quite a few areas where there wasn’t much yet growing from our seed. This big patch of marestail (Conyza canadensis) was representative of maybe 30% of the planting. I think this is a soil issue – in our alluvial soils, prairie plant communities can vary dramatically from place to place, based on the soil deposits beneath them. Restored prairies establish with great variation for the same reasons.

Canada milkvetch (Astragalus canadensis), hoary vervain (Verbena stricta), goldenrod (Solidago gigantea), and Canada wild rye (Elymus canadensis) make up a very nice patch of new prairie plants.

The wetland swales are filling in quickly with wetland plants, including lots of spikerushes, grasses, rushes, and a few forbs and sedges. Much of that vegetation came from our seed, but I think some also came from the seedbank.

We purposefully designed the wetlands to vary in their depth to groundwater so that we’d have some areas of standing water most of the time, but also many other areas that go dry each summer.

Some of the wetland pools had tadpoles in them, likely from the Woodhouse’s toads that have already colonized the area. I also saw leopard frogs hopping around.  In addition, numerous snails, and aquatic insects were moving around in the water, and dragonflies and damselflies were buzzing around above it.

This section of wetland had standing water a few weeks ago, but has now gone dry, leaving great habitat for shorebirds (but also for young cottonwoods).  The vegetation along the margin of this wetland is mostly native colonizing plant species such as fleabane (Erigeron annuus), yarrow (Achillea millefolium), and Canada wildrye.

Sweetclover (Melilotus sp) is abundant across much of the new site. Experience shows that sweet clover (though I don’t like it) doesn’t seem to actually affect plant diversity much in our restored prairies, so we’ll just let it go until the site is established well enough to support fire and cattle grazing. At that point, the cattle will keep the sweet clover suppressed because it’s one of their favorite plants to eat.

In addition to areas of strong native plant growth and others dominated still by non-native or “weedy” plants, there were also areas where bare ground was still plentiful. Again, alluvial soils make all of this really interesting because the soils vary greatly from place to place and strongly regulate plant growth.

Last year’s seed pods of Illinois bundleflower (Desmanthus illinoensis) show that this native perennial legume established and bloomed in its first year at the site.

Duck and raccoon tracks joined the tracks of many shorebirds along the edges of the restored wetlands. It’s really encouraging to see how quickly wildlife and insect species colonize these sites, even while the plant community is still young.

I’ll probably return to walk through this site numerous times this season because I can’t help myself.  Apart from working on cottonwood trees and a few musk thistles, however, it’s unlikely that we’ll actually do anything else here, so my visits will be mostly out of curiosity rather than to stimulate management.  As with this trip, I’ll see things on future walks that will encourage me and others that will make me wonder if the planting will end up as a disaster, even though I know it’s too soon to know anything.

Within the next few years, we’ll try to burn the new prairie whenever we can, and when the major grasses start to assert their dominance, we’ll begin grazing the site in ways that support a diversity of plants and animals.  Typically, that grazing begins when the site is between 5 and 8 years old.  In the meantime, there’s really nothing to do but wait.  (But I’ll still peek in now and then anyway.)

I was really glad to see coyote tracks along the edge of the site. The presence of these (relatively) large predators will be key to the long-term success of the ecological community in this restored prairie.

For those of you with technical questions about our restoration methods, we didn’t test our seed for viability, but based on previous experience, our seeding rate for this planting was probably about 2-4 lbs PLS/acre, about 2/3 of which was grasses and 1/3 was forbs, sedges, etc.  We typically broadcast our seed into recently harvested soybean fields, so this planting was a little different, but not that different.  We don’t mow weeds during the first season based on trials that have shown no difference in long-term establishment (sandy soils help keep weed densities low enough to still allow sufficient light to hit the ground, despite what it looks like in the 2016 photo in this post).  We don’t cultipack or harrow seeds in either.  We’re fortunate not to have much trouble with aggressive perennial invasive plants in our early plantings, which makes our weed control pretty easy.  Deciduous trees are the main exception to that, especially cottonwoods (as shown above) and Siberian elms (not too bad at this site).  Later, we see invasion by perennial cool-season invasive grasses, but we suppress those with fire and grazing.

Posted in Prairie Management, Prairie Natural History, Prairie Plants, Prairie Restoration/Reconstruction | Tagged , , , , , , | 17 Comments

Photo of the Week – May 12, 2017

When you look closely at Penstemon angustifolius, it’s easy to see why one of its common names is narrowleaf beardtongue.

Narrowleaf beardtongue is a widespread Great Plains wildflower that can have blue, lavender, or pink flowers – often, all on the same plant.  It is attractive to look at, and also (apparently) attractive to a number of pollinators as well.  The mason bee below was visiting the beardtongue growing in our backyard prairie this week.  According to Mike Arduser, there are some mason bees that specialize on penstemons, but from this photo, he couldn’t tell for sure if this is one of them.

A mason bee visits beardtongue blossoms – note the pollen stored on the underside of its abdomen rather than the strategy employed by most bees of storing pollen on their hind legs.

There are about 250 species of penstemon, most with very showy flowers.  Penstemons are popular in the horticulture world and you can read about the American Penstemon Society and other associated information here, if you’re interested.  I’m not interested in cultivating new varieties of penstemon – I just enjoy seeing the various species we find here in Nebraska.  If you’re not familiar with them, keep your eyes open; most of them will be blooming from now through about mid-June.

Posted in Prairie Natural History, Prairie Photography, Prairie Plants | Tagged , , | 6 Comments

2017 Field Days! (And a Photo Question)

Mark your calendars if you’re interested in attending either or both of our Platte River Prairies Field Days this summer.  The first will be on Thursday July 6, and will be focused on plant identification.  We’ll have several instructors on hand to lead field-based plant identification sessions in various habitats, including upland sand prairie, mesic prairie, and wetlands.  The second field day will be August 5, and will feature a wide range of topics covering prairie ecology, restoration, and management, pollinators and other invertebrates, and more.  Both days are free and open to the all ages.  Look for more details as the time grows near.

Now, a (minor) technical photo quandry I’m hoping you can help me with…

When photographing small flowers and insects, depth-of-field (the depth of an image that is in focus) is a challenge.  At close range, a camera can only bring into focus a narrow range of the image (front to back).  Deciding what needs to be in focus and what can be a little fuzzy is a constant issue, and I often try taking the image a few different ways so I can decide which I like best later.  When I’m photographing a small creature, I almost always make sure the eyes are in focus, regardless of everything else, because as viewers, our eyes are always drawn to the eyes of other creatures.

The eyes of this Woodhouse’s toad are both sharply in focus, but the tip of her nose/snout is a little out of focus – but not enough to be distracting.

When photographing the toad above, for example, I made sure the eyes were sharply in focus, even though i knew that would mean that the part of the toad closest to the camera (the center of its mouth) would appear slightly out of focus.  Because the toad was relatively large, the out-of-focus part was only a little soft and not at all distracting, making it an easy decision to prioritize the eyes being sharp.

Bee Photo #1

The other day, I was photographing a cute little green bee (Agapostemon sp.) on a dandelion flower.  I took quite a few photos, playing with the depth-of-field.  When editing the images later, I came up with two I really liked, but neither had the entire face of the bee in focus.  In the first photo (above), the front green portion of the head was in focus, along with much of the antennae, but eyes were a little soft.  In the second photo (below), the eyes are in focus, but more of the parts of the bee closer to the camera are not.  The second photo shows off the tongue and mandibles a little better, as well as the three simple eyes on the top of the bee’s head.

Bee Photo #2

Below, you can see cropped versions of both photos and compare them.  Again, the one on the left has the green part of the head in focus, while (all 5 of) the eyes are more sharp in the photo to the right.  If I follow my typical rule, I should like the second image better, but I’m not sure I agree with that in this case.  My question for you is this: as the viewer, what is the focal point in the photo?  The big compound eyes?  The point where the antennae meet the head?  Something else?   That focal point needs to be sharp, regardless of whatever silly rule I usually follow.

Here is a side by side comparison.

Ok, I know this is kind of splitting hairs, and the difference between these two photos is pretty slight, but I’ve had other situations in which the decision about whether to focus on a little critter’s eyes or another part of its face is more difficult.  I’m hoping to find out whether what I see as the focal point of these bee images is the same as what others see.  That will help me make future decisions with other images.

Thanks for your help.

Posted in Prairie Insects, Prairie Photography | Tagged , , | 23 Comments

Photo of the Week – May 5, 2017

During the last week, I’ve been lucky enough to find and photograph two different wolf spiders, so I figured I should probably dedicate a short blog post to them.  The first wolf spider I found was a cute little bugger out in the prairie the other day.  I was out looking for monarch eggs and caterpillars and saw the spider scurry between clumps of vegetation.  Since I had my camera in hand, I stopped and had a visit.  The second spider was in our basement and was considerably bigger (2 inches in diameter with legs).  I took it outside where it could be happier, and photographed it before letting it roam freely in our garden.

This big beautiful wolf spider was in our basement before I put it back outside.

There are a lot of big fuzzy spiders that resemble wolf spiders, but true wolf spiders have a characteristic eye pattern that sets them apart.  If you look at the above photo, you can see that there are two large eyes above a straight row of four smaller eyes.  If you look even closer, you might be able to see two additional eyes behind the big ones that point up and to the sides.  You can see those last two eyes more clearly in the photo below.  The layout of those eight eyes is unique to wolf spiders, so if you ever wonder if a big fuzzy spider is a wolf spider, just look it in the eyes and you’ll know.

In this photo, it’s easier to see the wolf spider’s non-forward facing eyes.

There are more than 2,000 species of wolf spiders across the world, and they are a fascinating group of creatures.  Although they are free-roaming spiders (they don’t create a web and hang out on it), they still use ambush as their primary means of hunting.  They’ll usually sit quietly and wait for prospective prey to come within striking range. Wolf spiders hunt mostly at night, and their eyes are well-adapted for seeing in low light.  However, wolf spiders are also very adept at sensing and using vibrations to identify their prey.  Their hairy legs aren’t just for looks; they also act as part of a complex system of vibration sensors.  Wolf spiders can distinguish between patterns of wing beats or footsteps to help them determine what kind of creature is coming near.

This small wolf spider was out in the prairie while I was looking for monarch caterpillars.  Its body and legs were about a half inch in diameter.  Note the distinctive eye pattern that characterizes it as a wolf spider and the different kinds of hairs on the legs.

My daughter made me proud the other day by telling me she was able to impress her college friends with some of my favorite spider trivia: the reason spider legs always curl up when they die.  Spiders have flexor muscles on their legs (muscles that pull the legs toward their bodies) but not extensor muscles to push them back out again.  Instead, they use hydraulic pressure to extend their legs.  A fluid called hemolymph is pushed into the legs, counteracting the flexor muscle pressure enough to extend the legs.  It sounds like a cumbersome system, but if you’ve ever seen spiders run and jump, it’s clear that it works very well.  When a spider dies, it no longer has hydraulic pressure in its legs to counteract the flexor muscles so the legs naturally curl up toward the body.

Don’t you just love spiders?  Of course you do.

Here’s the big female one more time, just before she turned away to go explore our garden.

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Frosty Monarchs

Adding insult to injury, the overly-ambitious monarchs in Nebraska this spring had to deal with cold wet weather all last weekend.  Temperatures got down to about 30 degrees F, and maybe lower in some places, and much of the prairie was covered in frost at least one morning.  During the days, it was rainy, windy, and cold.

We’d brought several monarch eggs from our garden into the house so we and the kids could watch them develop, and the caterpillars from those eggs seem to be doing very well.  When I went back to the garden, though, I didn’t find either eggs or caterpillars on the remaining plants.  I don’t know what happened, but I wonder if the caterpillars hatched out and then didn’t make it through the weather.  Maybe they’re just hiding really well?

Yesterday, I was out at our Platte River Prairies, and Katharine (Hubbard Fellow) and I spent a couple hours walking around and looking for caterpillars on milkweed with no luck.  In addition, the frost killed the tips of most of the warm-season grasses that were just emerging from the ground, and also wilted a lot of the common milkweed plants.  Interestingly, the whorled milkweed plants I’d seen caterpillars on during previous week seemed to have handled the cold just fine, but we couldn’t find any caterpillars on them.  We did find a few eggs on common milkweed plants, but it’ll be interesting to see how quickly those plants recover from the frost, and whether or not they are able to provide sufficient food for any caterpillars that hatch from those eggs.

This common milkweed plant looked a little wilted from the frost, but looked a lot better than the warm-season grasses surrounding it.

The common milkweed plant on the left was more typical of most of the plants we saw on our walk yesterday. Note the whorled milkweed on the right side of the image (skinny green leaves) – it looks perfectly fine.

This was one of several monarch eggs we found on common milkweed plants yesterday.  We found eggs on whorled milkweed as well.

There was good news from the day, though, which is that I saw two adult monarchs, one of which was nectaring on dandelions.  Maybe we’ll still see more eggs laid by this early migrant population.  Temperatures for the next couple weeks look pretty good, so those eggs might have both bigger milkweeds than their earlier counterparts and better weather as well.

This was one of two adult monarchs I saw yesterday. This one was so intent on feeding it let me army crawl to within a foot or so of it for a photograph.  Its faded color and rough-looking wings make it clear that it’s part of the migratory population that overwintered in Mexico.

While it’s been really interesting to see these monarchs show up early this spring, we’ve also seen some first-hand evidence of why we’re further north than those butterflies usually come to breed.  First, we were worried the butterflies wouldn’t find places to lay their eggs because the milkweed hadn’t emerged when they arrived.  Then we worried that caterpillars hatched out on those tiny milkweed plants might run out of food.  Now we’ve seen a frost and cold rainy weather that appears to have been hard on both caterpillars and milkweed.  Our prairies aren’t exactly giving those ambitious migratory monarchs a warm welcome.  Hopefully, we’ll see at least a few caterpillars turn into adults from this first generation, and their cousins further south will have better luck.  If so, we’ll see our regularly-scheduled influx of monarchs in a few weeks.  By then, we should be ready for them.

P.S.  Let’s just take a moment to appreciate the incredible journey the monarch in the above photo has made…  It hatched out of an egg late last summer, maybe even in Nebraska, and although its parents had been born near where it was born and hadn’t migrated anywhere, this one somehow knew that it needed to fly south.  Not only that, it knew to fly to a particular small spot northwest of Mexico City.  It somehow successfully navigated and survived the trip there, survived the winter with a horde of others like it, and then this spring, traveled about 1500 miles back north to get to the dandelion I photographed it on.  It’s a friggin’ butterfly, folks!  It’s just an amazing world, isn’t it?

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Photo of the Week – April 28, 2017

Ten days ago, I wrote about monarch butterflies returning from Mexico and flying much further north than is typical, and some of the risks they face because of that.  Many of you responded with your own similar observations and stories of monarchs across the country.  Since writing that post, I’ve spotted numerous monarchs both at our family prairie and in our Platte River Prairies, and reports to Journey North show monarchs have traveled even further north than we are here.

Earlier this week, my wife got to watch a monarch laying eggs on some small whorled milkweed (Asclepias verticillata) plants in our backyard prairie garden.  A monarch (same one?) came by when I was around too, so I snuck out and tried to get photos of it but it was too cagey.  At the end of last year, Kim and I were talking about how surprisingly fast the couple of small whorled milkweed plants we’d gotten for the garden had spread.  Now we’re worried that we don’t have enough whorled milkweed to support all the eggs that have been laid on them!

A monarch egg on whorled milkweed in our backyard.

Usually, the monarch laid only a single egg per plant, but some plants had as many as three on the same small plant. Hopefully, those caterpillars will be able to make their way to surrounding plants if they overwhelm the ones they start on.

Yesterday, I went walking in our Platte River Prairies, hoping to find some eggs there as well.  I was looking for common milkweed (Asclepias syriaca) but all I found was more whorled milkweed.  Sure enough, I found eggs on some of those plants too, and even spotted a couple tiny caterpillars.  All the plants I found were in prairie patches we’d burned and grazed last year.  I’m guessing the monarchs had the same impression I did of that grazed habitat – it’s sure easier to find tiny milkweed plants when there aren’t a lot of taller plants and thatch hiding them!

This tiny little caterpillar was busily munching away on whorled milkweed in our Platte River Prairies. It was just a couple millimeters long.

Whorled milkweed doesn’t usually get the accolades or attention it deserves.  In our prairies, it is often most abundant in areas where native prairies have been degraded by a long history of overgrazing and broadcast herbicide use (before we acquired the properties).  The plants are relatively small (often less than a foot tall) and have small white flower clusters and skinny seed pods.  When we’re harvesting seeds for our prairie restoration work, we try to get enough seed to ensure the species will establish in our plantings, but probably haven’t always worked as hard as we should at it.

Whorled milkweed is often overlooked and underappreciated, but is certainly proving its worth this spring.

The monarch eggs and caterpillars I found yesterday were in a restored prairie we’d seeded back in 2000.  The patches of whorled milkweed I found were over 15 feet in diameter, and some contained well over 100 plants.  I’m awfully glad now that we took the time to find and harvest whorled milkweed seeds during the summer of 1999, and wish we’d harvested even more.  Nevertheless, the plants that established back in 2000 have spread successfully and are now helping to rear the next generation of monarch butterflies.  When those caterpillars emerge as butterflies, they’ll find themselves in the middle of a large and diverse prairie community, full of flowers for them to feed on.  Eighteen years ago, that same location was a cornfield.  Today, it is giving some way-too-early monarchs a chance at survival.

This plant had both an egg and an already-hatched caterpillar. Hopefully, as it grows, it will find not only sufficient milkweed, but also abundant nectar resources for its adult life. (You can see a larger and more clear version of this image by clicking on it.  Maybe you can figure out what the little white bump is on the caterpillar’s back…  Part of the egg?  Something else?)

Posted in Prairie Insects, Prairie Natural History, Prairie Photography | Tagged , , , , , , , , , , | 13 Comments

How Small Is Too Small?

What’s the minimum effective size of a prairie?

For example, can a prairie be the size of a kitchen table?  Let’s say someone converted a landscape full of prairie to an immense gravel parking lot, leaving only a round kitchen table-sized parcel of vegetation in the middle.  Is that tiny isolated parcel a prairie?

The question might seem silly, but the question became a useful little thought experiment for me.

That little parcel certainly wouldn’t be big enough to meet the needs of most prairie animals.  Birds, small mammals, snakes, and even smaller creatures like grasshoppers and bees would be unable to find enough food to survive within that small area.  The loss of those animals would affect many of the ecological services and functions that make prairies work.  Those services include pollination, nutrient cycling, herbivory and more.

Even small creatures like grasshoppers would have a hard time surviving in a patch of plants the size of a kitchen table.

Some tiny herbivorous invertebrates might be able to survive in that little parcel of vegetation, but probably not enough of them to support most predators that feed on them.  The lack of predation would allow those invertebrate populations to grow much larger than they otherwise would, leading to significant damage, or even mortality, to the plants they feed on.  Once their food is gone, the invertebrates would starve and die as well.

Plants that manage to survive invertebrate attacks and an absence of pollinators in our little parcel would still face major challenges.  In the long-term, they would probably suffer from a huge genetic bottleneck because they don’t have other individuals of their species to cross breed with.  In the meantime, it would take a lot of intensive and thoughtful management to keep them alive.

Smooth brome and other invaders can quickly dominate small prairie patches without constant vigilance and suppression.

Invasive species management would be a huge problem because it wouldn’t take long for an aggressive invader to quickly dominate that small area.  Quick action would be needed to remove invasive plants as they arrive.  Fire or mowing would also be needed to prevent a smothering thatch from accumulating as plants grow and die back each year.  Unfortunately, every fire would kill most invertebrates aboveground at the time and destroy their food sources.  We could try to burn only a portion of the parcel and save some of the insects, but with such small populations, we’d still probably lose most species eventually.  Mowing and raking might be an alternative, but we’d still end up removing either the invertebrates or their food sources.

Ok, so we’d just have to live without most prairie animals, but we’d still have plants.  Or at least a few of them.  Some of those plants would be more competitive than others, especially in an animal-less environment, so it would take a lot of effort to keep them from pushing the less competitive plants out.  And, of course, we’re assuming the mysterious belowground processes that allow plants to survive would still function in our tiny parcel – microbial relationships that allow plants to access and process water and nutrients, for example.  If those are sufficiently intact, we’d have some plants.

Would that be a prairie?

I’m pretty sure no one would argue that a kitchen table-sized area containing few plants is a prairie.  Even in the first moments after the parking lot was created, I would argue the remaining patch of vegetation had ceased to be a prairie, even though it still contained a reasonable diversity of plants and animals. It wasn’t really a prairie anymore, just a doomed fragment of its former self.

If we can agree that a kitchen tabled-size patch of land is too small, how big would we have to make that patch before we’d be willing to call it a prairie?  What species and/or ecological processes should we use as criteria?

Can we agree a prairie needs to be big enough to support a healthy pollinator community?  Does it need to be able to sustain viable populations of small mammals, snakes, leafhoppers, spiders, and other little creatures?  Is it a prairie if it doesn’t have a full complement of grassland bird species?  Does that requisite bird community include larger birds such prairie chickens or other grouse species?  What about at least moderately-sized predators such as badgers and coyotes (or even bigger ones) or large ruminants like bison or elk?  Which of those components are we willing to live without, and more importantly, which can a prairie live without and still sustain itself as an ecological system?  A prairie without badgers, coyotes or bison is functionally different than one with those animals, but is it a non-prairie or just a different kind of prairie?

Bison herds need very large prairies, but we don’t know as much about the amount of land needed to sustain populations of bees, leafhoppers, jumping mice, or even genetically viable plant populations.

Even if we reach consensus on the key components of a prairie, we’re still hamstrung by our lack of information about how big a prairie needs to be to support each of them.  We have decent data on the prairie size requirements for many grassland bird species, but beyond birds, we’re mostly just guessing.  If we want the full complement of species, including bison and other large ruminants, we’re going to need thousands of acres, but how many thousands?

More importantly, what does this mean for the many remaining patches of prairie vegetation too small to support whatever we decide are the key components of a prairie?  It certainly doesn’t make them worthless, but it might be important to make sure we’re viewing them realistically.  What are the likely ramifications of the missing components?  The absence of prairie chickens or upland sandpipers might be disappointing, but might not have the ripple effect that the absence of pollinators or coyotes might have.  Can we identify and compensate for the absence of key prairie components by managing differently or more intensively?  If not, how do we adjust our vision of the future for that prairie parcel, and how does that adjusted vision affect how much management effort we invest?  (You can read more about the challenges of managing small prairies here.)

For many of today’s small prairie patches, the only chance of preserving their species and ecological functions is to make those small patches larger and/or more connected to others.  Restoring adjacent land back to high-diversity prairie vegetation allows formerly landlocked populations to expand and interact with others, and creates enough habitat for larger animals to survive.  Identifying potential restoration opportunities might be the highest priority conservation strategy for those of us working with small prairies.

Reasonable plant diversity and the presence of larval host plants like this prairie violet have so far allowed our family prairie to support a population of regal fritillary butterflies, but the small size and isolated nature of our prairie means if the butterflies have a bad year, they could easily disappear and never return.

Our family prairie is a little over 100 acres in size, is managed with large ruminants (cattle), and has regal fritillary butterflies, coyotes, badgers, upland sandpipers, and even an occasional prairie chicken.  However, I’m certainly not comfortable that our 100 acre island within a sea of cropland will to sustain a prairie ecosystem indefinitely.  This thought experiment has forced me to think more seriously about prospects for increasing the size of our prairie and building connectivity to other grasslands.  I hope it’s useful to others as well.

Posted in Prairie Animals, Prairie Management, Prairie Natural History, Prairie Photography, Prairie Plants, Prairie Restoration/Reconstruction | Tagged , , , , , , , | 11 Comments