Why Aren’t More People Talking About Migratory Flies??

Posted on by
13

About a century ago, there were lots of reports of migrating insects along the East Coast of North America. Among those were numerous sightings of large, apparently migratory congregations of flies. And then, for reasons no one seems able to explain, there is nothing about North American fly migration in the scientific literature for almost 100 years.

WHAT HAVE WE BEEN DOING THAT’S MORE IMPORTANT THAN FOLLOWING UP ON REPORTS OF MIGRATORY FLIES??

It’s unconscionable, really. There are flies. Migrating long distances. And no one thought to go out and learn more about this?

Ok, that’s not fair. There’s been some great work in Europe on migratory flies (and other insects) – much of it in topographic locations like mountain passes where flying migrants of many kinds are funneled through narrow locations. They’ve documented numerous fly species, especially in the family Syrphidae (hover/drone flies), making seasonal flights in huge numbers. There’s still an awful lot to learn, but at least they’ve made a good start.

What’s especially frustrating is that some of those same migratory fly species are here in North America, too, along with many other close relatives. If they’re migratory in Europe, they’re almost surely migratory here, right? So why has no one checked?

Eristalis tenax, the common drone fly, appears to be a migratory species in both Europe and North America.

Well, after the long, inexplicable century of ignoring this fabulous field of research, there have finally been two recent North American studies (One in California and one in Illinois) on the topic. Both have confirmed that flies do still migrate on this continent, but we still know almost nothing about which species migrate, where they go, and why. Let’s fix this!

In the meantime, while we don’t know much about fly migration here in North America – and have huge knowledge gaps in Europe and elsewhere – we can at least marvel at it. First of all, as is the case with most migratory species on our continent, fly migration is probably a way to escape cold temperatures in the winter and then to spread out (and escape competition) when temperatures are moderate. Birds aren’t the only animals cool enough to do this, no matter what snooty ornithologists will tell you.

(I don’t mean to imply that all ornithologists are snooty. In fact, many are surprisingly decent and nice to talk to. If an ornithologist was snooty, though, they’d surely be braggy about bird migration, wouldn’t they?)

You might not think of flies as cold tolerant animals, but many can survive sub-freezing temperatures. Body size is one predictor of that (bigger flies can generally survive colder temperatures.)

It appears that within at least many fly species, part of a population migrates south for the winter and the other part doesn’t. This is common among other insect groups as well. It’s a good way to hedge bets. If the subpopulation that stays put is wiped out by a particularly nasty winter, the migratory party can return and keep the species going. Or, if the migrants all die during their perilous journey, the ones who stayed home will persist.

How does an individual fly know if it’s supposed to migrate or hunker down for the winter? GEE, WOULDN’T IT BE GREAT IF WE KNEW SOMETHING ABOUT THAT??

Generally speaking, the assumption is that fly migration is a multi-generational phenomenon. The flies that head south in the winter have babies that then start the northward migration the following spring. By summer, either those progeny or their offspring will return to where their parents/grandparents had been the previous year. Of course, we don’t really know that BECAUSE NO ONE IS PAYING ATTENTION.

Drone flies like this one resemble bees but have bigger eyes, short antennae, and only two wings instead of four. THEY ALSO MIGRATE.

I’d love to continue this incredible, compelling story and provide lots more details. Unfortunately, as you might have gathered by now, we scientists have largely wasted a century doing less important work than fly migration research. As a result, I’ll just stop here.

This drone fly is clearly staring at us in astonishment because we’ve not been curious enough to learn about its (surely) epic migratory activities.

Photos of the Week – October 24, 2024

Posted on by
14

There’s been a lot going on this fall. Much of it has been happening up in the sky.

Milky way and stars above a campfire near the headquarters of the Niobrara Valley Preserve.

Most of my photography is focused on close-up photos of small things – insects, plants, fungi, and the like. As a result, I’m often looking downward as I explore and appreciate nature. There are times, though, that my attention is drawn upward toward something dramatic happening up in the air.

The first two photos shown here were taken at The Nature Conservancy’s Niobrara Valley Preserve back in September. We were hosting some TNC members for an event and enjoyed an evening campfire as the stars started to appear above us. The milky way put on a great show, which was visible despite the bright light from the fire and some of the nearby buildings.

After most people headed off to bed, a white glow started to grow along the horizon to the northeast. As some diffuse clouds moved across the sky, a full (or nearly full) moon popped up over the distant ridge. It was a scene worth staying up late for.

Moonrise and camp fire at the Niobrara Valley Preserve

A big component of my square meter photography project this year has been waiting for the sun to emerge each morning above the tree line to the east of my plot. Usually, I’ve got several insects and/or flowers spotted and ready to photograph and I’m just waiting for the light to hit them. Sometimes, though, I flip the script and aim at the sun instead of the subjects it is illuminating. As a result, I’ve got quite a few photos of the sun popping up above what has become a very familiar tree line.

Sunrise and Maximilian sunflower heads at my square meter photography plot.

Lots of people in central North America got to see the northern lights this fall. If you’re on any form of social media, you surely saw many results of people’s excited trips out to places dark enough to provide a decent view of the colored sky. The night of the best views, I’d just returned from a work trip and felt tired and a little under the weather (no pun intended). I hadn’t decided whether I was going to venture out, but Kim drove out of town and sent me a photo of a little purple light in the sky.

Since it’s pretty rare that we get to see the phenomenon here in central Nebraska, I decided I’d better not waste the opportunity. I drove west to a little prairie and started playing around. Suddenly, the muted purples gave way to a wild show of reds, greens, purples, and more. I no longer felt tired.

It was spectacular, and I had a hard time concentrating on photography because I just wanted to gaze in wonder at what has happening above me. I ended up doing some of both. I was moderately happy with the photos, but none of them came close to illustrating what it was really like to be out there under that sky.

Annual sunflowers and northern lights.
Prairie cordgrass with northern lights.
Mixed prairie plants with a nice red/purple background.

The northern lights were a popular sensation on social media, but Comet C/2023 A3 (Tsuchinshan-ATLAS) seemed to be even more popular – and harder to spell. I copied and pasted it here to make sure I got it right. That assumes, of course, that the website I copied it from had it spelled correctly.

I was fortunate to be back up at the Niobrara Valley Preserve the week the comet was most visible (I was helping with a bison roundup). I’d read up on where to see the comet in the sky and visualized what the scene might look like from my favorite vantage point near the Preserve’s headquarters. Sure enough, the first evening I was there, the sky was clear and the comet was right where I’d hoped.

Comet and Niobrara River Valley.
Comet over the “Nordern Chute” waterfall on the Niobrara River.
A closer look at the chute and comet.
Chute, comet, and rainbow (caused by the spray of the waterfall).

The morning after I photographed the comet, we arrived at the bison corral just as the sun was coming up. While the experts in charge of the proceedings worked through some final corral preparations, I took my drone up into the air to capture the sun rising over the Niobrara River.

Niobrara River and sunrise at the Niobrara Valley Preserve.

Near the end of the week the comet was most visible, I read that a “Hunter’s Super Moon” would be rising just after sunset one evening. That sounded like it might be worth checking out, so I headed to my square meter plot to see if I might be able to see both the moon and comet from there. The comet was hiding behind trees to the west and the town’s lights probably would have obscured it anyway. The moon, though, followed the same pattern as the sunrises I’d become familiar with. It was really windy, which made photography extra complicated, but I still managed to get a few shots of the super moon behind some of the plants in my square meter plot.

The Hunter’s Super Moon rising behind Lincoln Creek Prairie, as seen through my square meter photography plot.

Finally, I made one more trip up to the Niobrara Valley Preserve at the beginning of this week. Cottonwood trees were in full color and the autumn sky had just enough clouds to make the light and scenery really interesting.

Cottonwood tree in autumn color.

Just before sunrise on Monday morning, I was back up at my favorite vantage point at the Niobrara Valley Preserve, watching a ribbon of orange light illuminate the horizon and bleed into the dark blue/gray of the clouds above. I spent more than a half hour bouncing around a hillside, changing lenses several times, and lying on the ground in multiple places to get the angles I wanted. There were way too many choices for how to capture the scene and I wanted to take advantage of as many as I could.

Wide angle lens photo of the Niobrara River and lots of sky.
A close-up wide angle shot of some ground cherry fruits with the sunrise color in the background.
A telephoto shot of the river reflecting the colorful light behind it.
A long telephoto image of the ribbon of orange between the horizon and the dark clouds above.
Using the same telephoto lens, I was able to frame lead plant against the same band of orange.
I switched to a macro lens to silhouette these wild rose hips against the colorful sky.

By the time the sun actually breached the horizon, I was heading to meet some college students and take them out to see bison, prairie, and other wonders. We found everything we were looking for – all of it under a fantastic autumn sky.