Monthly Archives: May 2018

Hubbard Fellowship Post – Mixed-Up Flickers

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This post is written by Olivia Schouten, one of our Hubbard Conservation Fellows.  Olivia hails from Pella, Iowa, and has strong experience in prairie ecology.  Look for more posts from her, as well as our other Fellow, Alex Brechbill, in coming months.

One of my favorite things about the change from winter to spring is the return of migratory birds. While the rest of spring has been reluctant to arrive, I am still reminded of the inevitable change in season as more and more birds arrive in the area. What started with sandhill cranes back in February just continues as killdeer, turkey vultures, and swallows, among others, seem to appear overnight when a favorable wind blows from the south.

Among the new arrivals are northern flickers, a woodpecker that despite its name, tends to feed on the ground. This migratory bird arrived here on the Platte River quite suddenly over Easter weekend, and they’ve been everywhere ever since! While common across North America, if you’ve spent any time travelling and recognize this bird, you may have noticed something interesting: birds in the eastern half of the continent are not the same color as those in the west.

In fact, there are two color variants of northern flickers. Eastern birds are called yellow-shafted flickers, and those in the west are red-shafted. The ‘yellow/red-shafted’ designation refers to the unusual coloration on the shafts of the wing and tail feathers of this bird. Where most birds’ feathers either have white, brown, or black shafts, northern flickers’ are bright yellow or salmon-red, depending on the variant. The undersides of these feathers also display the same color, resulting in bright flashes of color when the birds fly, turning a somewhat drab bird into something spectacular.

There are some other differences between the eastern and western variants. Yellow-shafted birds have a red crescent on the nape of their neck, and while all males have a ‘mustache’ patch of feathers extending down their cheek, it is black in yellow-shafted males, and red in red-shafted males. These differences are so clear, that for many years the two variants were considered different species.

This red-shafted flicker displays the red mustache sported by the males of this species.  Photo by Chris Helzer

In contrast, yellow-shafted northern flickers have a red crescent at the nape of their neck, and the male’s mustache is black. All flickers have a bold black crescent across their chest. Photo by Olivia Schouten

Though overall drab in appearance, northern flickers flash bright yellow or red when in flight. This yellow-shafted male followed around the female at the left of the photo for several minutes. Notice the female is missing the mustache of the males. Photo by Olivia Schouten

However, what complicated that classification was the presence of hybrids of the two variants in a large zone stretching from Texas to Alaska, cutting right through the heart of the Great Plains, including central Nebraska. These hybrids, called intergrades, display combinations of facial traits found in the red- and yellow-shafted variants. In my home state of Iowa all you will see are yellow-shafted flickers. However, here in Nebraska I see flickers with their wings flashing everything from yellow to dark salmon red, and all colors in between.

Though I couldn’t get a clear picture of this bird in flight, it is still clear that the wings of this bird grade from yellow to orange. While the facial markings of this flicker suggest it is a yellow-shafted variant, the coloration of the wings point to it being an intergrade, the result of the hybridization of a yellow-shafted and red-shafted variant. Photo by Olivia Schouten

Now considered one species, northern flickers are just one example of a common trend seen among North American birds. If you flip through a bird field guide and study the range maps, you will often find pairs of similar species where one occurs in the east, and one in the west, with the transition between the two occurring right down the middle of the continent. Eastern screech-owls and western screech-owls, ruby-throated hummingbirds and black-chinned hummingbirds, eastern and western wood-pewees, eastern and western meadowlarks, vireos, bluebirds, warblers, and on and on and on, you can’t escape the pattern. For many, it’s as if there was an invisible wall through Oklahoma, Nebraska, South Dakota, and upward keeping these species from spreading any further.

Clearly, something is going on in the middle of the continent when it comes to birds, and this hybridization sometimes makes it difficult for ornithologists to determine where species begin and end, or whether they should even be considered different species at all. One of the leading hypotheses is that climactic changes during past ice ages created unsuitable habitat in the center of the continent that separated previously connected populations. Time allowed for the divergence of these now separate populations, and when they reconnected as the ice retreated, enough differences had accumulated that they were no longer the same species.

Of course, this divergence was carried to varying degrees of completion depending on the bird. While some of these species pairs, like flickers, hybridize quite readily, and in fact never quite diverged enough to be different species at all, others, such as meadowlarks, while nearly identical in appearance, developed different enough songs that their separation was maintained.

So pay attention to the flickers around you here in Nebraska and elsewhere along the hybrid zone, and see if you have can spot the different variants!

Though I’m not entirely sure what is happening in this photo, I believe the male flicker here was displaying its tail to the female in some sort of courtship behavior. Whatever it was doing, it made for a nice demonstration of the brightly colored feathers tucked away by this otherwise unassuming bird. Photo by Olivia Schouten

Toxic Bee-Killing Hitchhiker Beetles (I Know, Right?)

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I’ve said many times that I’m no entomologist.  I am an invertebrate enthusiast.  I enjoy photographing small things, which means I end up with a lot of images of tiny invertebrates.  Once I have photos, I love to figure out what it is I’ve photographed and how it fits into the incredible complexity of its ecosystem.  The only times I’m ever disappointed by that research is when I can’t find any good information – often because there just isn’t much known about whatever creature I’m looking up.  When I can track down a story, it is always fascinating, and reinforces my sense of wonder about the world.

The latest example of that came last week while I was photographing pasque flowers at the Niobrara Valley Preserve.  I noticed a few bees and other insects hanging around the flowers, but most were too wary to be photographed – with one big exception.  There were several big black beetles with large bulbous abdomens and short wings feeding on pasque flowers.  They were intent enough on feeding that I was able to get a few decent photographs, and promised myself I’d look up the species later.  Before I had a chance to start doing research, former Hubbard Fellow Jasmine Cutter texted me some photos of what looked like the same kind of beetle feeding on pasque flowers up in North Dakota and asked if I knew what they were.  Nope, but I was going to.

An oil beetle feeding on pasque flower at the Niobrara Valley Preserve last week.

After a rare failed attempt to use Bugguide.net, I sent photos to a couple friends and James Trager responded quickly with the answer – oil beetle (Meloe sp.), a kind of blister beetle.  Once I started looking for more information, I was shocked that I’d not come across oil beetles before.  Ok, not shocked, exactly, since there are way more great insect stories out there than I’ll ever learn, but still surprised, given the abundance of oil beetle accounts online.  Of those, I particularly recommend Piotr Naskrecki’s The Smaller Majority blog, as well as Adrian Thysse’s Splendour Awaits site.

So, what did I learn? First of all, oil beetles produce the same kind of toxin as all other blister beetles – a compound called cantharidin.  Ingesting only a small amount of cantharidin is toxic to most vertebrates.  While that seems like a great way for an oil beetle to get revenge on anything that eats it, it doesn’t necessarily prevent the big flightless beetle from being attacked and killed in the first place.  Don’t worry – there’s more.  When an oil beetle feels threatened, it can secrete bright yellow hemolymph (the insect equivalent of blood) from its leg joints.  As one does.  That hemolymph contains enough cantharidin that any contact with the skin of potential predators causes painful swelling and blisters.  That, of course, is a pretty good deterrent against predators, as well as any foolhardy humans trying to manhandle an oil beetle.

As a side note, cantharidin has been long recognized by humans as a powerful chemical.  Despite its extreme toxicity, it has actually been used (in very small doses) as an aphrodisiac, starting at least a thousand years ago.  Because of the severe consequences of even a slight overdose, however, there are gruesome stories of hopeful lovers causing very painful deaths to themselves or others.  Cantharidin also has a long and varied history in medicines.  Currently, it is being tested for its effectiveness at treating cancer (as in this recent example).

The wings of oil beetles are much too small carry their weight.

The ability to secrete toxic bright yellow fluid from its leg joints is a pretty good story.  However, that just scratches the surface of the fascinating natural history of oil beetles. Most beetles mature through a process called complete metamorphosis, in which larvae  hatch out of eggs and grow until they pupate and become adults.  The larvae usually look completely different from the adult, and often have a very different lifestyle as well.  Oil beetles, however, go above and beyond by using a process called hypermetamorphosis.

When an oil beetle egg hatches, what crawls out is called a triungulin, a speedy little creature that looks much like a tiny silverfish.  The triungulin cluster together and emit a chemical that mimics the pheromone of female solitary bees (bees that individually make nests and raise young, as opposed to honey bees and other social bee species).  A male bee, upon catching the scent, will descend upon the mass of triungulin and attempt to mate with it (guys are so dumb when they’re horny).  Instead, the triungulin quickly crawl up onto the bee and hold on tight.  They stay with the male bee until it finds a genuine female bee and mates with her, at which time the triungulin scramble aboard the female.

Once onboard the female bee, the triungulin hitchhike back to her nest burrow.  When they arrive, they detach themselves and start eating everything then can find in the nest, including the bee eggs and larvae, along with the food the mother bee provisioned for them.  You can watch an incredible short video of oil beetle triungulin here.  During their time in the host bee’s nest, the triungulin molt into much more traditional grub-like larvae, and eventually pupate and turn into adults.  As adults, oil beetles feed on vegetation – including, apparently, pasque flower blossoms.

You’d never know by looking at its cute face that this oil beetle spent its childhood eating baby bees.

Do you see what I mean about the fascinating lives of invertebrates?  Who would’ve guessed that a bulbous-butt flightless beetle would have such a great story?  Answer: anyone who knows much about invertebrates.  As I write this, I have my booted broken ankle propped up awkwardly on the couch, but I’m already formulating plans for how I’m soon going to (carefully) drag myself out into the prairie to collect more images and stories of tiny little creatures.  Stay tuned.