Something Blue

One of the most striking plants in our prairies this time of year is pitcher sage, also known as blue sage (Salvia azurea).  It’s tall, of course, but more importantly, as the surrounding prairie is dominated by green-becoming-gold grasses and big yellow flowers, pitcher sage stands out simply because it is starkly and unabashedly blue.

A few weeks ago, I posted a photo of a bee that specializes on pitcher sage, but there are many more insects commonly seen on the plant.  Last week, I spent about 45 minutes in our Platte River Prairies, photographing pitcher sage and as many visitors as I could.

.

I initially pulled my camera out because there were several monarch butterflies flitting around a patch of pitcher sage.  While chasing them around (and, as always, being thankful no one was watching me), I came across quite a few other insects – some of which I managed to photograph.

A sulphur butterfly (and a second partially shown at the bottom left) enjoys pitcher sage.
Anthophora walshii (a digger bee) is a species I see on pitcher sage frequently, and this was just one of several hanging around a single patch of flowers.
This moth was nose deep.
Several skipper butterflies were around, including this sachem skipper.
Not all the insects were feeding on pollen and nectar.  I’m not sure what this plant bug was doing, but there it was.
This blister beetle was feeding on the flower itself.
This monarch was so distracted by the nectar of pitcher sage, I took this photo from about a foot away with a wide angle lens.
One more monarch…

In addition to being tall, striking, and beautiful, pitcher sage is also pretty good at withstanding drought.  During late August of 2012 – a year of extreme drought, pitcher sage stood out against a background of brown dormant grass, blooming just like it does every year.  Not only did it provide some welcome color when many other plants were wilting, it gave all the insects pictured above, and many others, something to eat when they needed it most.

What a great plant!

A Tough Plant, Not A Weed

I blame whomever named the plant.  Giving a plant the name “ironweed”, apparently – according to Google – because of its tough stem, creates an unnecessarily negative connotation right from the start.  It’s an unfair connotation for a plant that is both beautiful and important.  It’s also a big favorite of butterflies; something I can attest to after spending a couple hours last weekend chasing monarchs and others around ironweed patches at our family prairie.

Ironweed at our family prairie, growing abundantly in a smooth brome-filled draw.  The abundance of the plant goes up and down each year, but it never spreads beyond the draw or shades out the grass around and beneath it.

There are three species of ironweed (genus Vernonia) in Nebraska, and two that are common in the prairies I am most familiar with.  Both of those – V. fasciculata and V. baldwinii – seem to act in similar ways, but the first likes a little wetter sites than the second.  Both species can occur as scattered plants across a prairie, but are also often found in fairly dense patches where conditions favor them.  That patchy local abundance is the first mark against them by people who don’t appreciate their value.  The second mark is that cattle absolutely refuse to eat them.  This both helps them stand out (especially when blooming) in heavily grazed pastures and helps them spread across those same sites since they gain a strong competitive edge when surrounding plants are all being grazed hard.

Like many other plant species I tend to admire and write about, however, ironweed is not an invasive plant – it’s an opportunist.  It takes advantage of soil and management conditions that favor it, but doesn’t just spread aggressively across pastures.  If you look online, it’s not hard to find websites that encourage its control in pastures.  I dispute that.  At least in my experience, ironweed has its favorite locations (often in draws or other low spots where moisture and nitrogen are high) and pulses in abundance within those locations as grazing treatments and weather vary from year to year.  At our family prairie, ironweed is fairly abundant in some of the low draws where high nitrogen also strongly favors smooth brome, but while there are years when those patches are thicker than others, the overall patch sizes and stem densities of ironweed aren’t any higher today than they were 15 years ago.  That matches what I see elsewhere in central and eastern Nebraska.

(I found a university website online that blamed ironweed for making cattle have to look harder to find grass, thus reducing grazing efficiency.  Give me a break.  That’s the same attitude that leads to people spraying pastures to remove everything that isn’t grass, and then wondering why they need to fertilize their grass and supplement their cattle’s diet.  The same people blame others for the lack of wildlife and pollinators on their land.  …Ok, I’m done ranting – let’s talk about butterflies.)

When I arrived at our family prairie last weekend, I immediately noticed monarch butterflies flying all over the place.  I’d seen a surprising number of larvae back in July, so figured we might have a good August, but I was still impressed with how many adults I saw.  I’m guessing there were 40-50 or more across our 100 acres of prairie.  They kept moving, so it was hard to count them…

Almost every monarch I spotted was either flying or feeding on ironweed.  A few other flowers got attention too, including wild bergamot (Monarda fistulosa), Flodman’s thistle (Cirsium flodmanii), and some early tall thistle blossoms (Cirsium altissimum), but ironweed clearly monopolized most of their attention.  I started stalking monarchs with my camera and eventually found a couple that let me get close enough for to capture reasonable photographs.  While I was doing that, I also spotted myriad bees, along with quite a few other butterfly and moth species.

Here are some photos of the butterflies and moths that were kind enough to let me get close.  I didn’t ever get a good shot of a bee, though there were at least a dozen species feeding on the ironweed flowers, and I also never caught up to one of the many silver-spotted skipper butterflies that were all over the place.

This is one of many monarchs that were floating from plant to plant across ironweed patches last weekend.
I haven’t looked up this moth yet. Maybe one of you can save me the trouble? Thanks in advance.
I’ve been seeing a lot of adult swallowtails around lately, including this tiger swallowtail , which was pretty easy to spot, even from across a large draw.
Ok, this black swallowtail wasn’t on ironweed when I photographed it, but it went to ironweed after feeding on this native thistle.  I was taking bets (in my head) about whether or not the crab spider on that thistle would be able to take down the big butterfly. The butterfly eventually moved within striking distance, but the spider didn’t attack, so I’m guessing it decided to wait for something a little smaller.
Thanks to Neil Dankert, I can tell you that this gorgeous little brown skipper butterfly is a tawny-edged skipper.

Ironweed is too beautiful and important for its name.  Maybe we need a campaign to rename it, and maybe that campaign would help convince people, including those at a certain unnamed university, to leave this plant alone to do its job.  Either way, it might be fun to think about potential names.  Any ideas?

Photo of the Week – October 20, 2017

I’ve written before about the value of native thistles, both to pollinators and other parts of prairie ecosystems.  Tall thistle (Cirsium altissimum), in particular, seems to be a key food resource for pollinators during the late growing season, including the migration period for monarch butterflies.  Here in the Platte River Prairies, we include native thistles in our seed mixes for prairie restoration work and try to promote them through our management activities.  Here are some photos of tall thistle from last month.

This bee was one of many feeding from tall thistles this fall.
Skippers like this one often feed from thistles, but this one was just resting on top of a half-empty seed head.
While bees get great value from tall thistles, this one got trapped and killed by the sticky substance on the bracts beneath the flowers (which is probably meant to capture nectar-stealing ants).
Tall thistle seed.
More tall thistle seeds.

Photo of the Week – September 29, 2017

As the growing season comes to an end and most wildflowers wind up their blooming period, insects that feed on nectar and pollen have to work a lot harder to find food.  The few remaining plants with active flowers suddenly become really popular.  In this part of Nebraska, those last remaining wildflowers include species like tall thistle (Cirsium altissimum), heath aster (Aster ericoides), and New England aster (Aster novae-angliae), among others.  The other day, I spotted a lone New England aster plant being mobbed by hungry insects.  Here are some photos…

 

Over the five minutes or more that I watched the horde of insects on this plant, I saw the same individual blossoms get worked over multiple times by multiple insects.  After all that activity, I can’t imagine any of those insects were really getting much of anything out of those flowers, but they were certainly trying…

Painted lady butterflies are still pretty abundant, but not nearly as abundant as they were a year ago.

How many insects can you find on the photo below?  I can find four painted lady butterflies, a skipper butterfly, three different bees, and a tree cricket.  Not pictured are a couple of grasshoppers and a few other bees that were just below the field of view.

How many insects can you see?  Click on the photo to see a larger version of the image.

I assume the remaining painted lady butterflies will migrate soon, but most of the other pollen and nectar-eating insects around here don’t have anywhere to go.  Some will simply die with the flowering season, but others will spend the winter in a state of dormancy and re-emerge in the spring.  I sometimes use the analogy of watering holes in Africa when talking about flowers and pollinators.  In this case, the analogy seems particularly apt as the last “watering holes” are drying up and the animals relying on them are highly concentrated.  I was surprised not to see any “crocodiles” (e.g., crab spiders) at this particular watering hole, taking advantage of an increasingly desperate prey base.

I appreciate living in a temperate zone where I can enjoy a nice variety of seasons through the year, but I’ll certainly miss seeing (and photographing) flowers and insects over the winter.  It’s hard to focus on indoor work these days, knowing that my opportunities to see those flowers and insects this season are dwindling fast…

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.

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?)

The Life of a Single Mom (Bee)

Most of what we read in the news about declines in bee populations focus on (non-native) honey bees.  Yes, those populations are suffering declines from the combined impacts diseases, habitat loss, pesticide use and other factors.  However, there are nearly 4,000 bee species in North America, and many of them are dealing with the same pressures and threats as honey bees.  In addition, honey bees are social insects, living in large collaborative colonies of workers and queens.  The vast majority of bees in North America, however, are not social, and they succeed or fail on the backs of single moms.

Solitary bee
At first glance, some solitary bees might appear similar to honey bees (I’ve certainly been guilty of making that mistake many times) but while their appearance might be somewhat similar, their life stories are very different.  This one is a solitary bee in the genus Svastra.  At least I think it is…

Solitary bees – bees that don’t live in colonies – are all around us, but they go largely unnoticed.  Many escape our attention because of their small size, but others are as big as or bigger than honey bees.  Solitary bees can vary greatly in their diet preferences.  Some are generalists, feeding on nectar and pollen from a wide variety of flower species.  Others have much more narrow diets, feeding only from sunflowers, for example, or other categories of flowering plants.

Most solitary bees in prairies live in underground burrows, though others live in hollow plant stems or similar spaces.  In colonies of social bees, the work of gathering food, maintaining and defending the home, and feeding and caring for the kids is split between hundreds or thousands of bees.  In the case of solitary bees, the single mom does everything.  In most cases, she finds a likely spot, digs a burrow and prepares it for eggs.  Then, she flies around the neighborhood in search of the kinds of flowers she can collect food from.  As she nears the flowers, she’s likely to encounter males of her species, who basically spend their entire lives buzzing from flower to flower, hoping to find females to mate with.

Male
A male solitary bee (Dufourea sp.) waits for females at a sunflower.

Assuming the single mom can find food nearby, she returns from foraging with a load of pollen and nectar, which she combines into a ball of sticky dough.  She places that in a cell within her burrow, lays an egg on or next to it, and seals up the cell.  Then, she takes off to repeat the process: find food, mix it together, lay an egg with it, seal up the cell.  Later, the eggs will hatch, and the larvae will stay in their cells and feed on the dough balls provided for them until they grow into adults and leave the nest.

As you might imagine, life isn’t easy for single mom bees.  They have to gather food for themselves and their kids, while fighting off overly-enthusiastic males with only one thing on their minds.  When they aren’t out finding food, they are building and provisioning baby rooms or sitting vigilantly at the entrance of the burrow, defending it from marauding wasps or other threats.  After mother bees have filled their burrow with eggs-in-cells, they seal up the whole nest and fly away, hoping for the best.

Single mom solitary bees have difficult lives, but there are ways we can help them.  First, we can help ensure the availability of nesting sites.  Some ground-nesting bees need areas of bare ground, and many others need at least access to the soil without having to fight through a dense layer of plant litter.  Similarly, stem nesters would appreciate it if you didn’t chop down all of last year’s plant skeletons, especially those of raspberry, sunflower, rose, leadplant, and other plants with hollow stems.  Providing this kind of nesting habitat is important in prairies and other natural areas, but also in backyard gardens and other urban areas.  Because solitary bees aren’t aggressive toward humans, there’s no downside to sharing your yard or garden with them (and, as pollinators, they’ll work for their housing).

A "long-horned bee" (Melissodes sp) on dotted gayfeather (Liatris punctata).
A “long-horned bee” (Melissodes sp.) on dotted gayfeather (Liatris punctata).

Perhaps more importantly than housing, what bees need most is food.  The key to supporting strong bee communities is plant diversity.  A prairie or garden with lots of different kinds of flowers will support lots of different kinds of bees.  Specialist bees will be able to find the particular flowers they need, and generalist bees won’t run out of food when one kind of flower stops blooming, gets eaten by insects, or is wiped out by disease.  Early spring can be a particularly difficult time for bees to find food because of the relative scarcity of flowers at that time of year.  Boosting the spring-time abundance of both native wildflowers and flowering shrubs in gardens and natural areas can be very helpful.

In prairies and other large-scale habitats, it’s important to think about the flight range of bees.  Honey bees can travel up to several miles to find food.  Most solitary bees are considerably smaller, however, and they may be limited to a range of a few hundred yards or less from their nest.  During their nesting season, bees will need to find everything they need to survive and supply their nests from that relatively small circle of habitat.  The availability of abundant flowers of many kinds within that circle helps ensure that bees can find food throughout the season.  If a large area surrounding a bee’s nest is mowed or grazed intensively, it is left stranded with a nest in the middle of a food desert.

this
This tiny sweat bee fits perfectly into this puccoon flower (Lithospermum carolinense).  Its size gives it access to flowers larger bees (including honey bees) can’t get into, but that size also limits its ability to forage far from its nest.

If you’re a landowner or land manager, think about your property from the perspective of a single mom bee.  Pick a few spots on your land and visit them every few weeks to see what the abundance and diversity of flowers looks like.  If a bee was nesting where you stand, could she find what she needs for food within a short distance of that location?  Are there times of year when it’s hard to find abundant flowers?  If so, can you tweak your management or implement restoration strategies to make more flowers available?  Are there places where bees can find bare soil for nesting, or is there a layer of thatch covering the soil across your whole site?  Burning, intensively grazing, or haying portions of your land each year can help reduce thatchiness and help ensure bees’ access to soil.  However, creating patches of prairie habitat representing a full spectrum of vegetation structure types (tall/dense, short/sparse, mixed-height, etc.) will be of maximum benefit to both bees and other insect and wildlife species.

Single mom bees deserve our respect and admiration.  They build and prepare their nest, seek out and harvest food while dodging predators and lustful males, and provision their eggs with food and a safe place to grow up.  Oh, and along the way, they also pollinate and help ensure the survival of the majority of plants on earth.  It seems only fair that we should acknowledge their work and do what we can to help them out.

 

More information:

While the vast majority of native bees are solitary bees, some are social as well, including bumble bees, some sweat bees, and others.  Bumble bees, in particular, are very important pollinators because of their size and mobility as well as their willingness to visit many different kinds of flowers.  As opposed to honey bees, whose colonies can survive the winter intact, all bumblebee individuals except fertilized queens die at the end of the growing season.  Those fertilized queens overwinter and then become single moms in the spring.  Once the queen’s first brood matures, those bees take over the foraging work and take care of the queen.  You can learn much more about solitary bees and other native bees here.

Many thanks to Mike Arduser and Jennifer Hopwood for reviewing this post for accuracy.  Any remaining errors are mine, not theirs.

Photo of the Week – December 9, 2016

Rocky Mountain bee plant (Cleome serrulata) is very pretty, for a weed.  It’s an annual plant that grows in disturbed areas like road edges and around livestock watering tanks.  In that sense, many people would call it a weed.  However, it’s also a beautiful native wildflower that can grow more than four feet tall and is a favorite among pollinator insects.

Rocky mountain bee plant in the Nebraska Sandhills.
Rocky mountain bee plant in the Nebraska Sandhills.

Around Nebraska, I see Rocky Mountain bee plant mostly in the western 2/3 of the state on sandy or loess soils.  It can colonize bare soil pretty quickly in young prairie restorations or after dirtwork projects, and also likes places where perennial vegetation is continually stomped down by cattle or otherwise severely weakened.  It doesn’t seem to withstand much competition, however, and usually disappears pretty quickly once other plants start to enter the scene.  In our Platte River Prairies, we see it often in the first year after we plant a restored prairie, but rarely after that.

More
Rocky Mountain bee plant with seed pods.

While it is not in the mustard family, Rocky Mountain bee plant’s long skinny seed pods that dangle beneath the flowers are certainly reminiscent of mustard plants.  (It is in the same order – Brassicales – as mustard plants.)  Interestingly, while the plant has an unpleasant smell and isn’t often eaten by herbivorous animals, there are many traditional uses by humans that include dyes, medicine and food.  It is also an extremely attractive plant to bees and other pollinators, and the seeds are readily eaten by birds.

Paper wasp
This paper wasp was feeding on nectar.
Bumblebee
Bees like this bumblebee (Bombus griseocollis) are particularly attracted to Rocky Mountain bee plant, as the name would suggest.

There are many plant species that colonize areas where other plants have been removed, weakened, or haven’t yet established.  It’s a really important role in nature, but one that is often underappreciated, and even denigrated – thus the label of “weed”.  Many colonizing plants lack pretty flowers, are spiny, or otherwise make themselves easy to dislike.  A few, though, are so attractive that even the staunchest weed haters might hesitate at labeling them as something bad.

A Milestone for Prairie Restoration

Because conservation work can sometimes seem like blowing into the wind, it’s important to pause periodically to celebrate progress.  For example, I am really excited about what has been accomplished in the field of prairie restoration.  We’ve known for a while that we can convert cropland to prairie vegetation with a high diversity of plant species (150 or more species per planting), and that we can do that on a scale of thousands of acres.  The Nature Conservancy has large projects in states like Indiana, Illinois, and Minnesota where restored prairie landscapes now range from about 5,000 to 20,000 acres in size.  The U.S. Forest Service is transforming an old U.S. Army Arsenal into 20,000 acres of prairie in Illinois.  Prairie Plains Resource Institute, the organization that pioneered restoration techniques in Nebraska, is planting up to 1000 acres a year now and has established well over 10,000 acres total across the state.

Our staff celebrates a successful year of seed harvest back in 2015.
Our staff celebrates a successful year of seed harvest back in 2015.

Here in our Platte River Prairies, we’ve restored more than 1,500 acres of cropland to prairie.  That’s not insignificant, but more importantly, we’ve been testing the idea that those restored prairies can help defragment the ecological landscape around them.  Habitat fragmentation is one of the largest threats to today’s prairies because it shrinks and isolates populations of species, making them vulnerable to becoming locally extinct without the chance of recolonization from nearby sites.  The real promise of prairie restoration is that it can enlarge and reconnect scattered remnants of native prairie, providing populations of animals and plants a much better opportunity to survive and thrive.  It’s not feasible or desirable to convert the majority of cropland in the central North America back to prairie, but there are particular sites where strategic restoration work could make a huge difference in the potential survival of prairie species and ecological services.

In order for prairie restoration to help defragment landscapes, restored prairies have to provide suitable habitat for the species living in small isolated prairies.  Many bees and other insects specialize on certain plant species, for example, and other animals rely upon an abundance of prey, a diversity of seeds, or other particular food or habitat conditions.  Satisfying the individual needs of all those prairie animals is a critical measure of success if prairie restoration is going to successfully stitch isolated prairies back together.

Over the last several years, we’ve been collecting data to see whether the species of bees, small mammals, grasshoppers, and ants in our unplowed prairie remnants have moved into adjacent restored habitat.  The results have been very positive.  While not every species of animal living in our remnant prairies has been found in nearby restored habitat, we’ve found the vast majority of those we’ve looked for.  We suspect that most of the remaining species are also present but that our limited sampling effort just hasn’t yet picked them up.  We’ll keep trying.

Dillon Blankenship, a Hubbard Fellow, compared grasshopper, katydid, and tree cricket communities on three pairs of remnant/restored prairies back in 2014. Almost all species were present in both restored and remnant habitats. In the three species that weren't, only one or a very few individuals were found, so it's likely just a sample size issue.
Dillon Blankenship, a Hubbard Fellow, sampled grasshopper, katydid, and tree cricket communities on three pairs of remnant/restored prairies back in 2014. Almost all species were present in both restored and remnant habitats. In the three species that weren’t, only one or a very few individuals were found, so it’s likely just a sample size issue.
Data from James Trager and Kristine Nemec has helped us compare ant species composition in restored versus restored prairies along the Platte River. So far, we've documented 30 species and only one has been found exclusively in remnant prairie (and, again, it's likely to be a sample size issue).
Data from James Trager and Kristine Nemec has helped us compare ant species composition in restored versus restored prairies along the Platte River. So far, we’ve documented 30 species and only one has been found exclusively in remnant prairie (and, again, it’s likely to be a sample size issue).
Master Naturalist Mike Schrad and Hubbard Fellow Jasmine Cutter have both helped us compare small mammal populations between restored and remnant prairies. This table shows some of Jasmine's data from one site. In general, we're finding that the same species are in both restored and remnant prairies, but the relative abundance of those species is often different - with some apparently favoring remnant habitat and others favoring restored areas.
Master Naturalist Mike Schrad and Hubbard Fellow Jasmine Cutter have both helped us compare small mammal populations between restored and remnant prairies. This table is from Jasmine’s data from one site, showing the number of trapsites in which each mammal species was caught back in 2014. In general, we’re finding that the same species are in both restored and remnant prairies, but the relative abundance of those species is often different – with some apparently favoring remnant habitat and others favoring restored areas.  We’re now looking at how our management affects presence and abundance of each species through time.
We've had several research projects look at native bees in our prairies. Mike Arduser, Anne Stine (Hubbard Fellow), Bethany Teeter, and Shelly Wiggam Rickets have all helped us compare restored and remnant prairies. So far, we've found over 72 species and the vast majority have been in both remnant and restored prairie.
We’ve had several research projects look at native bees in our prairies. Mike Arduser, Anne Stine (Hubbard Fellow), Bethany Teeters, and Shelly Wiggam Rickets have all helped us compare restored and remnant prairies. So far, we’ve found over 72 species and the vast majority have been in both remnant and restored prairie.
I've collected more than 15 years of data showing that plant diversity and the frequency of occurrence of prairie plant species has remained stable through time. These four graphs show four species in one restored prairie where we're comparing fire/grazing management to fire only management.
I’ve collected more than 15 years of data showing that plant diversity and the frequency of occurrence of prairie plant species has remained stable through time. These four graphs show four species in one restored prairie where we’re comparing fire/grazing management to fire only management.  The long-term persistence of prairie plants and diverse plant communities is critically important for plant communities, but also for the success of efforts to defragment habitat for animals.

These results mean that where prairie landscapes have been largely converted to row crops, we don’t have to just watch while insect or small mammal populations careen toward local extinction in tiny isolated prairies.  We’ve shown that we can make those prairies larger and more connected, and that animal populations can grow and use new restored habitat and diverse plant communities.  We’ve also shown that restored prairies can sustain their biological diversity for decades, even through periods of intensive grazing and drought.  While there are still plenty of questions and potential improvements we can make, we’re now at the point where society needs to decide whether and where to do this kind of restoration.

I don’t know about you, but I think that’s pretty exciting!

Nebraska and other states in central North America have large swaths of productive and important cropland.  As I said earlier, I’m not advocating that we convert most of that back to prairie.  However, there are specific sites where row crop agriculture is marginally productive/profitable and the long-term interests of both society and local landowners might be best served by putting land back into diverse and productive grassland.  Agricultural policies and subsidy programs will obviously play a huge role in this kind of strategic large-scale restoration, and getting the policies in place to facilitate this kind of common sense restoration will be plenty difficult.  That’s nothing new, however.  What’s new is our confidence that if we can implement targeted restoration work, it can make a real difference to prairie conservation.

Restoring the viability of prairies in fragmented landscapes is critically important to prairie conservation success.  The challenges of conserving species in small isolated prairies are immense, and many of those prairies will continue to see declines in biological diversity and ecological function over time unless we can make them bigger and more connected with other prairies.  Helping to document our ability to do that – at least for many prairie species – has been one of the most satisfying things I’ve done during my career.

 

Important footnote:  Restored prairies are not the same as remnant unplowed prairies.  Soil organic matter levels, for example, can take many decades to recover from tillage, and relationships between plant and microbial communities may take just as long to become reestablished.  Our success in prairie restoration should definitely not be used as justification for plowing up remnant prairie!  However, it’s equally true that prairie restoration efforts aren’t failures just because they can’t create an exact replica of prairie as it existed before it was converted to farmland.  If defragmenting prairie landscapes is the primary goal of restoration, we just need to create restored prairies that complement – not copy – remnant prairies. 

 

Saving Pollinators One Thistle at a Time

Pollinator populations are in trouble for a lot of reasons.  Loss and degradation of habitat, pesticides, and diseases are all major contributors.  However, at least in the Central United States, much of the pollinator decline can be tied to spiny pink/purple-flowered plants and the way humans react to them.

Tall thistle, a native annual wildflower, is a big favorite among pollinator insects.
Tall thistle, a native annual wildflower, is a big favorite among pollinator insects.  However, it is seen by many people as a weed that needs to be eliminated from the earth.

On the face of it, thistles seem like they’d be pretty well-liked.  Thistle seeds are a major food source for birds and other wildlife, as well as for a variety of invertebrates. The abundant nectar and pollen found in thistle flowers make them one of the most popular plants among both pollinator and non-pollinator invertebrates.  As if that wasn’t enough, most thistles have large and/or abundant blossoms, which you’d think would make them very attractive to people.  Sure, they’ve got spines, but so do cacti, yucca, and many other plants gardeners love to landscape with.  So why do we hate thistles so much?

The cultural dislike of thistles is not at all a new phenomenon; references to the unpopularity of thistles can be found at least as far back as the Book of Genesis in the Bible.  There, thistles are mentioned when God curses Adam after he eats the forbidden fruit. Genesis 3:17-18 – “Cursed is the ground because of you… Both thorns and thistles it shall grow for you…”  Clearly, if God includes thistles as part of His curse on all humanity, they are not a crowd favorite.

Regardless of why thistles are so widely disliked, our contempt for them causes serious problems for pollinators.  This happens in two ways: 1) direct destruction of an important floral resource for pollinators, and 2) major side effects associated with #1.

Because thistles are so important to pollinators, our compulsion to destroy them is a major problem.  Sure, some thistle species are invasive and can cause enough ecological damage that their control is warranted.  Most thistle species, however, are targeted for destruction purely because they are thistles.  Many of those are native wildflower species and are not at all aggressive or problematic.  Regardless, there are few places where thistles are tolerated, let alone encouraged.  The result is the loss of a big source of food for many pollinators.

Musk thistles and regal fritillaries (before we chopped them because they are designated as noxious weeds and we are legally obligated to eradicate them.) The Nature Conservancy's Platte River Prairies, Nebraska.
Musk thistles and regal fritillaries.  Musk thistles are designated as noxious weeds and we are legally obligated to eradicate them.) The Nature Conservancy’s Platte River Prairies, Nebraska.

While the loss of thistles themselves is a big problem for pollinators, the methods we use to eliminate them can have much bigger impacts.  If we were content to dig thistles out of the ground one by one, things wouldn’t be so bad.  Of course, that’s not always feasible – some perennial species such as Canada thistle are rhizomatous and can’t be killed by digging.  Herbicide use is the other available option.  Spot spraying individual plants or clumps can be relatively innocuous, but only if the person spraying is judicious and selective about what they spray.

However, working thistles one by one takes a lot of time, and just because we hate thistles doesn’t mean we want to spend a lot of time getting rid of them.  Broadcast herbicide spraying, by airplane or boom sprayer, can kill lots of thistles in very short order.  It’s a great way to get rid of all those unsightly pink flowers in one fell swoop…at least for that season.  Unfortunately, broadcast spraying also kills a wide array of other wildflowers, and most of those never recover (the ones that do are the ones we tend to like least – like ragweeds).

The grand irony is that because broadcast spraying kills so many non-target plant species, the spaces left open by those dead wildflowers are usually colonized by thistles.  Thus, while broadcast spraying is quick, it tends to perpetuate thistle populations by destroying their competitors.  (Also, most large thistle populations are there because of chronic overgrazing or some other major disturbance that weakens perennial vegetation and creates space for thistles to grow.  Broadcast spraying doesn’t address those underlying issues.)  Oh, and by the way, killing off all the wildflowers in a pasture or roadside also wipes out the pollinators that depend upon them for food.

Our cultural dislike of thistles leads us to kill off as many as we can each year.  Since thistles are a major food source for pollinators, that’s grave news for pollinator conservation.  Our desire for more “efficient” ways to kill thistles has led to even worse news, however – the loss of plant diversity across millions of acres.  Since plant diversity sustains pollinators by providing varied and consistent food through the season, losing that diversity at a large scale is devastating.  We can rebuild some of what we’ve lost through restoration, and we can save what’s left, but only if we change the way we think about thistles.  We’d better hurry; pollinator declines are not slowing down.

I think we need a thistle fan club.  Who’s with me??  Let’s do this thing.  I’ve come up with a basic logo and tag line (below) to get us started.  Click here to get an easily printable version you can hang on your office door or tape to your car window.  It’ll be a great conversation starter!  In fact, let’s have fun with this.  If you feel like it, take a picture of how you displayed the logo and put it on your favorite social media with the hashtag #thistlehelp.  Not a social media person?  Feel free to email me a photo – maybe I’ll collect some of them and use them in a future post.  If you email me, please keep the file size below 1 mb…   Use this email address: chelzer(at)tnc.org.

The bees and butterflies of the world are depending on you.  This is going to sweep the nation, you’ll see!

ThistleFanClub