Photo of the Week – March 30, 2018

Spring is almost here.  I spotted my first butterfly this week (too far away to identify it) and there are a few other insects starting to move around as well.  Not much flowering in the prairies yet, though plants are starting to green up, especially where we’ve burned.  While I wait for the new season to fully kick into gear, I’m falling back to a popular (to me) theme of “Random Photos from Last Year” to fill the gap.  Enjoy.

Anyone know what this insect is? (Other than a hemipteran) I photographed it at our family prairie last summer.  It looks predatory to me, but what do I know?
The Niobrara River, flowing through our Niobrara Valley Preserve. This is a stretch of river I don’t photograph very often, but there is a great photo waiting for me in this location.  I haven’t quite found it yet, but this photo is heading in the right direction.
This gorgeous wasp was feeding on butterfly milkweed at Lincoln Creek Prairie here in Aurora.
This is a giant blowout at the Niobrara Valley Preserve, but it’s unlike most blowouts in that it has steep bluffs on the north and south sides that have a texture almost like sandstone. We found a burrowing owl nest on the south bank a couple years ago.  There’s a great photo waiting for me here too.  Someday I’ll find it.
I mainly put that last photo in as a precursor to this one. It was taken at the southeast corner of the big blowout where the sand blows most actively.  I’m a sucker for waves of sand.  I could spend all day looking at them and never get bored.

That Predator Just Killed My Predator!

I spent last week in the Nebraska Sandhills, possibly the greatest grassland in the world.  Last week’s trip was one of several I’ve gotten to make around that landscape this summer.  It’s been great to see a much wider swath of the Sandhills than I have in previous years, and my appreciation for the area has grown even stronger than before.

The big sand tiger beetle (Cicindela formosa) has been eluding me this summer, but I finally get a good set of photos of one eating a recently captured ant.
The big sand tiger beetle (Cicindela formosa) has been eluding me most of this summer, but I finally got a good set of photos of one eating an ant.  Clicking on this and other photos from this post will give you a larger and more clear image to look at.  It’s worth it.

In a previous post, I wrote about the importance of Sandhills blowouts as habitat for species that thrive in bare sand.  I’ve been trying to document and photograph as many of those creatures as I can this summer.  Some of the most difficult to photograph have been tiger beetles.  These incredible predators run very quickly along the sand in search of small insect prey, but can also fly easily when they see me or other scary things approaching.  It’s been fun to chase them around, but the vast majority of attempts to photograph them end in them flying away just before I’m close enough.

One of the species I’ve been unable to photograph so far is a beautiful metallic blue tiger beetle called the sandy tiger beetle, aka Cicindela limbata.  You can read more about this critter in a great blog post by Ted MacRae.  I had seen and admired the beetle, but was running out of time to photograph it before my trip ended.  Finally, I spotted it again, and started stalking it.  (I should mention that I was doing this while 7 other people were watching and waiting for me, semi-patiently, so we could move to another location.)

I edged close to the beetle, but (as usual) just as I got almost within photo range, it took off and flew about 15 feet away.  I let out a small sigh and starting creeping toward its new location.  This time, it took off when I was still five feet away.  However, just as the tiger beetle left the earth, a big gray robber fly streaked up from the ground nearby and knocked the beetle right out of the air.  It was like a ground-to-air missile attack, but much faster.  The two tumbled back to the sand together, the tiger beetle firmly in the clutches of the robber fly.

The robber fly and tiger beetle landed upside down right after the initial attack.
The robber fly and tiger beetle landed upside down after the initial attack.  For scale, the tiger beetle is about 1/2 inch long.

As I watched, the robber fly got back to its feet and struggled to keep a hold on the beetle.  Though I couldn’t see it happening, I knew the fly was also injecting the beetle with toxic saliva to immobilize it.  Eventually, the saliva would also liquefy the innards of the beetle so fly could consume the resulting beetle soup.

Upright again, the robber fly tried to hang on to the beetle while injecting it with toxic saliva.
Upright again, the robber fly tried to hang on to the beetle while injecting it with toxic saliva.
The robber fly had to periodically readjust its grip as the tiger beetle struggled to escape.
The robber fly had to periodically readjust its grip as the tiger beetle struggled to escape.

Within a few minutes, the beetle seemed to stop moving.  Having taken approximately 10,000 photos of the scene (from the perspective of my waiting colleagues), I grudgingly got up off the sand and backed slowly away to move on to our next site.  I still don’t have a stand alone photo of C. limbata, but I’ll get one someday.  In the meantime, I feel like I had a front row seat for a miniature version of the kind of predator/prey attack usually seen in nature documentaries from the Serengeti.  I can live with that.  As I’ve said numerous times before, I’ve got a pretty good job…

A final look at these two magnificent predators.
A final look at these two magnificent and beautiful predators.

Sand Wasps

I was introduced to sand wasps (Bembix sp) by Mike Arduser when he came to visit the Platte River Prairies back in 2012.  As we stood together in a sand prairie, a bee-like creature was zipping around us with incredible speed.  Mike explained that it was a sand wasp, and that it wasn’t interested in us, but rather was looking for flies that might be hanging around us.  Since that day, I’ve paid much more attention to sand wasps and have seen them all over the place in sandy places.

Sand wasp (Bembix americana spinolae) burrowing in sand in a blowout. The Nature Conservancy's Niobrara Valley Preserve.
Sand wasp (Bembix americana spinolae) burrowing in sand in a blowout. The Nature Conservancy’s Niobrara Valley Preserve.  This wasp was about 1/2 inch long.

While we were exploring a big sand blowout last week at the Niobrara Valley Preserve, there were lots of sand wasps buzzing around, and we found some of their nest burrows.  I took a little time to sit near a couple nests and photograph the females as they worked to excavate them.  The wind appeared to be blowing just as much sand back into the holes as the bees were digging out…

Here's the same wasp as above as it digs sand out of its burrow.
Here’s the same wasp as above as it digs sand out of its burrow.

The video below shows both the blowing sand and the valiant effort of the wasp to excavate its burrow despite the wind.  If the video doesn’t appear correctly, try clicking on the title of this post to view it through an internet browser.

Mike tells me these sand wasps and their relatives catch and paralyze flies for their young.  They lay eggs in their burrows and provide the flies as food for the larvae.  Females, of course, do all the work to create the burrows, catch the flies and lay the eggs.  The males are just around for mating purposes.  While the wasp larvae eat flies, both the adult males and females feed on nectar and pollen.

Here are a few more images of the sand wasps we saw last week, along with the blowout they were living in.

A big blowout where wind keeps sand moving and open.
A big blowout where wind keeps sand moving and open.
The sand wasp shown earlier takes off and twists its body to zip away.
The sand wasp shown earlier takes off and twists its body to zip away.
This was a little smaller wasp from a different species that was nesting in a different part of the blowout from the first wasp.
This was a smaller wasp from a different Bembix species that was nesting in the same blowout as the first wasp.
...and that wasp was also digging its burrow.
…and that wasp was also digging its burrow.

As often happens with invertebrates, once I’ve been introduced to a creature, I start seeing it everywhere.  Even better, I’ve yet to meet an invertebrate that doesn’t have a fascinating background story.  It’s an awesome world we live in, and we share it with some pretty great neighbors.

Thanks, as always, to Mike Arduser for his help with identification and ecology.

In Defense of Erosion

The Nebraska Sandhills region consists of about 12 million acres of sand dunes with a thin layer of vegetation draped across them.  That vegetation has come and gone over the last several thousand years, as long-term climatic patterns have shifted from wet to dry and back.  We are in a relatively wet period (geologically speaking) today, and grassland is clinging to the hills.  For now.

Except where it can’t.  Here and there, throughout the sandhills, particularly on steep hills, sand breaks through.  Most of the time, blowouts are triggered by a combination of topography and some kind of physical disturbance.  A two track road or cattle trail up a steep slope, for example, or a favorite hangout of livestock.  Just as with frayed fabric, once a small hole in the vegetation starts, it tends to spread.  Most Sandhills ranchers see blowouts as a great risk to their livelihood and work hard to prevent them, or to heal them once they start.  Those ranchers are encouraged in that view by watchful neighbors and a long history of agencies and university extension staff warning of the dire impacts of wind-induced soil erosion.

Small blowouts dot the steeper hills in the background and a couple larger ones appear in the foreground.  Overall, these make up a tiny percentage of the landscape, but many ranchers see them almost as badges of shame.
A very large blowout like this can cause not only a loss of forage for a rancher’s livestock, but also a huge challenge for fence maintenance.

The Sandhills is ranch country, and all but a tiny fraction is privately-owned and managed for livestock production.  Most ranchers are conservative with livestock numbers and grazing strategies, trying to preserve that thin fabric of grass that feeds their livestock, and thus their families.

While there are certainly places that are prone to wind erosion and practices that can accelerate it, the risk of blowout creation and spread has also become a kind of mythology.  In much of the Sandhills, blowouts are actually difficult to create (we’ve tried) and the percentage of a ranch that could potentially be covered by blowouts is very small.

Sometimes, wind erosion digs a blowout deep enough that it intersects groundwater, creating wetlands.

While conservative grazing has helped maintain healthy prairies in the Sandhills, it has also led to a loss of open sand habitat for a group of plant and animal species that depend upon blowouts and similar areas.  Those species are important, but asking a rancher to allow, let alone encourage a blowout, is much like asking a business man to go to work wearing Bermuda shorts with his sport coat.  The peer pressure and social norms associated with blowouts can be more influential than any potential loss of livestock forage they might cause.  Just as farmers judge their neighbors by the weeds in their fields, Sandhills ranchers judge their neighbors by the blowouts in their pastures.

Blowout grass (Redfieldia flexuosa) is one of a select group of plants that can colonize a blowout and begin to stabilize the sand.
Blowout penstemon (Penstemon haydenii) is a federally listed endangered plant that is found exclusively in blowout habitats.  This one is in a blowout that is healing and might not support penstemon populations much longer.
tiger beetle
Many species of tiger beetles can be found in Sandhills blowouts, including several of conservation concern.  These impressive predators hunt small insects in patches of open sand.
lesser earless lizard
Lizards, including this lesser earless lizard and other species, are often seen in and around blowouts, where they can forage in open areas but retreat quickly to cover to escape predation.

Regardless of the social or economic ramifications of blowouts for ranchers, bare sand patches really are important habitats for many prairie species.  The discussions I’ve had with ranchers about the ecological values of blowouts have always been polite, but I can’t say they’ve been met with great enthusiasm.  I understand that, but that doesn’t change the need to continue having those discussions.

Spiderwort (Tradescantia occidentalis) grows on the edge of a large blowout, surrounded by bare sand and a cast of other plants struggling to survive in the shifting substrate.

It may be that changing climate will render moot our discussions about whether or not to allow or encourage blowouts in the Sandhills.  Eventually, we will experience enough consecutive years of hot dry weather that even the most conservative grazing won’t prevent widespread blowing sand once again.  We can’t predict whether those conditions will arrive in the next few years, or not for many decades.  When they do arrive, both the ecological and human communities of the Sandhills will be glad to have species that are well adapted to open sand.  Plants like blowout penstemon and blowout grass, for example, can help restabilize areas of bare sand, and they also provide food for both livestock and wildlife.

For now, the Sandhills provides a vibrant grassland that supports both humans and wildlife.  That will likely change at some point in the future.  Hopefully, blowout-dependent species will find enough habitat to maintain their populations until we really need them.

…and hopefully no one will feel like they have to wear Bermuda shorts in order to make that happen.

Photo of the Week – February 8, 2013

I just got back from a trip through the Nebraska Sandhills.  The trip included a brief stop at the beautiful Switzer Ranch – home of Calamus Outfitters, a ranch family-owned business providing opportunities for bird watching, hunting, river floating, photography, and other activities.

Small mammal tracks across rippled sand in a sandhills blowout.  Switzer Ranch, Nebraska.
Small mammal tracks across the rippled sand of a sandhills blowout. Switzer Ranch, Nebraska.

It was late afternoon at the ranch, and light from the dropping sun was angling sharply across the prairie, including a large blowout full of the tracks of several animals.  (A blowout is a bowl-shaped area of actively moving sand.)  Though it was February, temperatures had been above 50 degrees F for a couple days, and it was clear that the warm weather had stimulated numerous creatures to emerge from dens to explore and search for food. 

They’d better make good use of their time – the weekend forecast calls for a return to snow and cold temperatures.