Flight of Dragons

Although growing up, I was very much a tomboy, climbing trees and mucking around in the bush and ditches near my house, my relationship with insects was more typical of most city girls. I didn’t like them.  I thought nothing of swatting a house fly and I’m sad to say that I’ve run, screaming, away from a pursuing horsefly or the longhorn beetles that show up around August at the cottage.

However, as I’ve aged, my impression of insects has evolved quite a bit.  As I’ve grown to appreciate the amazing beauty and complexity of our natural world, I find myself drawn more often to those things that used to frighten or disgust me to re-examine them with my new perspective on life. I’m pleased to report that I’ve developed a new appreciation for longhorn beetles.

However, the one group of insects has always fascinated me, even as a child, is the dragonflies. I have a vivid memory of canoeing with my father down the La Salle River, south of Winnipeg, when a dragonfly landed on my knee.  I was rapt as I carefully held my lower half as still as I could while paddling to ensure my visitor a smooth ride, wanting to keep it with me as long as possible.

I’m not the only one with this fascination. There’s just something about these bejewelled predators that captures the imagination. I see representations of dragonflies everywhere, on t-shirts, in wind chimes and other household decorations, on jewellery and even fridge magnets. I think most people simply find them attractive, with their iridescent colours and delicate wings. They’re also ‘benevolent bugs’ from the human standpoint, voraciously devouring our ‘undesirables’ like mosquitoes and black flies.

Even with all of this goodwill, I don’t think the average person really knows all that much about them.  Dragonflies, and damselflies belong to the order Odonata (toothed ones), which contains some of the most ancient and largest insects ever known. There are over 5,900 living species, with nearly 100 of them found in Manitoba.

They’ve been around a long time, with the earliest fossil Protodonata (pre-dragonflies) dating to around 325 million years ago.  They were also a lot larger then, with wingspans reaching nearly a metre. I’m not sure we would’ve been so fond of them if they were still that size. When these insects first took to the air, they were the monarchs of the skies, feeding on whatever flew into their path. Vertebrates were only just crawling out of the water and so dragonflies had little competition and few predators. The benefits of being big, however, only lasted until dinosaurs started coming into their own.

Although they’ve become much smaller over time, the overall structure of a dragonfly hasn’t really changed all that much in 250 million years. These bugs are built to hunt on the wing. Their compound eyes are enormous relative to the size of their body and over 80% of their brain function is devoted to analyzing the visual input from the up to 30,000 ommatidia (facets) that make up each eye.  Having eyes made up of independent facets results in an incredible ability to detect movement because they can see in just about all directions at once.

This hyped-up visual centre can also detect parts of the colour spectrum that we can’t. Human eyes have three types of opsins, light-sensitive proteins that detect red, green and blue light. Diurnal dragonflies have four or five types of opsins arranged very specifically throughout each compound eye, with blue and UV receptors pointed up and longer wavelength receptors pointed down, likely to maximize their efficiency.

With amazing visual acuity, the ability to focus on one prey item at the expense of all else, almost all of their limbs facing towards the head and prehensile labia (mouthparts), they can snatch their prey out of the air with about a 95% success rate.

The last part of this deadly equation is their stunning aerial ability. We’ve all seen them dive and weave, hover and back-up, all while reaching speeds of nearly 50 km/h.  Dragonfly flight is actually very complicated, probably the most complex process of all flying organisms.  With four wings that can move independently of each other and dynamic airfoils that can flex around several angles, things can get complicated and scientists are still trying to sort it all out with the help of high-speed film.

They can make use of the classical lift that keeps planes in the air and a back and forth figure-eight stroke much like hummingbirds as well as take advantage of the vortices they create.  Some can turn 360 degrees around the axis of their bodies with the wings on one side stroking forward and the other side stroking back in one coordinated movement.  All of it is driven by a circuit of 16 neurons hard-wiring the brain to the highly developed motor muscles in the thorax.

So, the next time you catch the flash of a dragonfly as it zips along, take a moment to marvel at these truly ancient wonders of the natural world.

A Thing With Feathers

Even if you can somehow go through your entire life without ever seeing a bird, chances are very good that you will still have some experience with feathers. Whether displayed in a  hatband, stuffed into a pillow or quilt or tied together at the end of a duster, feathers are a fairly ubiquitous part of the world around us and certainly the defining characteristic of the group of flying vertebrates we know today as birds.

But, have you ever given much thought to where they came from?

As it turns out, feathers have been around a lot longer than most people realize. As paleontologists find more fossils every year to slot into the puzzle that is the evolution of life on this planet, the picture becomes clearer and stories start to make sense.

When it comes to the story of the evolution of feathers, the first thing you have to remember is that birds are modern dinosaurs, having evolved from the lineage known as Theropods, whose ranks include those Jurassic Park villains Velociraptor and Tyrannosaurus rex.  However, what didn’t make it into the movies was the fact that, at the very least, Velociraptor was not only ferocious, but fluffy. At first, this detail was inferred from the discovery that many of its ancestors were feathered and some, like the bizarre, bi-plane like creature Microraptor gui, could fly. Then, a discovery of quill nobs, a trait seen in modern birds, on the forearm bones of one specimen confirmed it. Now an accurate representation of Velociraptor is something like a sleek, predatory ostrich.

Even more recent discoveries have put the assumption of a scaly hide in Tyrannosaurus rex into doubt. While they haven’t found specimens of this iconic dinosaur with feathers yet, a cousin from about 125 million years old China, named Yutyrannus most definitely was feathered. About the size of a bus, these are the largest feathered dinosaurs known to date.

So how far back do feathers go? In time, we can trace their existence at least 160 million years to chicken-like dinosaurs called Anchiornis, but these critters already had the highly complex barbed feathers we see in modern birds today.  Most evolutionary biologists agree that feathers likely started out as single, hollow,  hair-like filaments that became branched and barbed as needed over time. These have been found in many species, most notably, Sciurumimus, a dinosaur found very near the base of the Theropod branch. Described for the first time just last year, this species shows a spectacularly preserved coat of dense, filamentous plumes. Finding feathers like these near the base of the branch suggests that maybe more advanced Theropods, including T-rex had some kind of plumage. Still, we don’t know just how far back down the tree they go.

The point of origin keeps getting pushed closer and closer to the root of at least the dinosaur’s evolutionary tree thanks to feather filaments being found in some Ornisthischian dinosaurs, like the Triceratops cousin, Psittacosaurus, who are about as far removed from Theropods and modern birds as a dinosaur can be. Actually, they’re starting to find feathers all over the dinosaur family tree, leaving us to wonder if they predate the group altogether. In fact, the genes responsible for taking an undifferentiated plate of keratin and turning it into a feather has been found in crocodilians, who although they are birds’ closest living relatives, branched off from the group well over 250 million years ago.

So what did these prehistoric feathers look like? Structurally, early feathers started out as simple, hollow strands, growing out from a plate of keratin embedded in the skin. More advanced feathers split into barbs, looking like fluffy ostrich plumes. Eventually, those barbs developed tiny barbules that allowed their wearers to ‘zip them up’, turning them into strong, but flexible sheets that eventually were co-opted into airfoils. This same evolutionary progression can be seen today in the growth of every bird embryo.

Most fascinating, however is the fact that paleontologists now know what colour some of these plumes were. Recent work with Anchiornis turned up microscopic pockets of pigment called melanozomes. By comparing these ancient structures to those known today, they managed to work out that not only was Anchiornis about the size of a chicken, it actually kind of looked like one, a bright tableau of shiny black and white spangles with a flash of red on a crest. Who knows, maybe in time, we’ll see our very own field guide to dinosaur plumage. Either way, you can’t help but marvel at these remarkable, ancient, ingenious  and unarguably beautiful innovations of evolution.

In the Bleak Midwinter

It was minus 40 Celsius with the wind chill the other morning. The bite of the air stung any carelessly exposed skin and the snow squeaked like Styrofoam underfoot. Wrapped up in my shearling coat, I couldn’t help but watch in fascination as a nearby mountain ash came alive with foraging Pine Grosbeaks and the cheerful chirps of chickadees and nuthatches filled the frosty air, reminding me just how incredible these tiny winter residents really are.

Chickadees, for example, weigh not much more than 10 g, about the same as two nickles. Yet, they can survive quite comfortably in temperatures that would leave us frostbitten and shivering.

Winter birds accomplish this seemingly unfathomable feat in a number of different ways. Firstly, they’re wearing a down coat. Those of you who own one know just how warm they can be and for birds, that insulation is part of the standard package. Feathers are a remarkable insulator. Comprising only about 5 – 7 % of a bird’s body weight (that’s half a gram on a chickadee), the air trapped within them makes up 95% of that weight’s volume, creating a thick layer of dead air that traps heat generated by the body, preventing much of its loss even on the coldest of days. Many winter residents grow a thicker winter coat, much like mammals, augmenting their feather count by up to 50 %. Fluffing feathers increases their insulation factor even further (about 30%), making them a very efficient way to keep warm in the winter, so efficient, in fact, some birds, like Great Gray Owl can actually overheat in the summer.

While some species, like Ruffed Grouse and many owls, grow feathers, along their legs and feet, like fluffy winter boots,  most songbirds’ legs are bare, thin sticks of sinew, blood and bone exposed to the elements. Although birds can tuck these delicate structures up into the warm cover of down when temperatures really plummet, most of the time they’re out in the open. So, why don’t they freeze and why isn’t all of a bird’s body heat lost through these naked limbs? Bird legs are marvels of biological efficiency, having been streamlined by millennia of evolution into sleek structures with very little muscle and few nerves, using instead pulley systems of tendons and bone to accomplish movement. These tissues, along with their scaly coverings have very little moisture and are less likely to freeze than flesh and skin.

Birds also have cold feet. Using a common natural system called a countercurrent heat exchange, our feathered friends keep their feet upwards of ten to twenty degrees colder than their core body temperature. Warm arterial blood on its way to the feet pass right next to colder blood coming back towards the body through the veins. Heat wants to reach a point of equilibrium, so warmth from the arteries passes into the veins which carries it back into the body. Because the flows are running opposite to each other, it’s impossible for the heat balance to ever reach equilibrium, so by the time the blood gets to the feet, it’s much cooler than when it entered the leg and all that precious body heat has been kept where it needs to be, in the core.

However, as most of us who have experienced a true northern winter know, a coat alone isn’t always enough. There has to be heat to trap in order for insulation to work over the long term. To generate that heat, many winter birds shiver constantly when they’re not moving. Ravens, whose feather count isn’t as high as some of its more fluffy distant cousins, actually shiver constantly, even when flying, the repeated contractions of their massive pectoral muscles acting like a furnace. Powering that furnace takes energy and cold-weather specialists meet those needs by upping their metabolic rate, in some species, to several times their normal levels. As a result, food is always a going concern in winter.

Many winter residents can only forage for food during the day, so keeping the internal fires burning at night can be a challenge.  Finding a warm place to settle in for the night reduces those metabolic needs.  Densely-packed spruce boughs or old tree cavities are perfect nighttime microclimates and many birds use them. Chickadees will often take it a step further, piling as many fluffy little birds as possible into an old woodpecker hole to share body heat, which may just be too much cuteness in one place. Ruffed Grouse take advantage of the insulative capacity of snow in a somewhat comical way. One cold nights, the birds dive head first into a drift and tunnel deeper into the snow, creating a cave known as a kieppi. Temperatures inside the kieppi can hover just around the freezing mark, even when it’s minus thirty outside.

So as we close in on the shortest day of the year and sink deeper into the cold clutches of winter, take a moment, now and then, to marvel at those tiny survivalists outside your window. Much of the technology that keeps us from succumbing to winter’s icy grip was adapted from them. Nature truly is our greatest teacher.

Given to Fly

I never get tired of watching birds fly. It’s something that’s always entranced me: a warbler flitting between sun-dappled leaves, a gull wheeling lazily against the clear blue of a Manitoba summer sky, or the subtle whisper of an owl’s feathers as it returns to roost.

My fascination with flight started at an early age, much to the consternation of my parents who had to cart me off to the hospital to get my foot x-rayed after an ill-fated attempt to get airborne from the top of a ladder with willow branches strapped to my arms.

I’m pleased to report that there was no permanent damage and I now have a much better grasp on the mechanics of avian flight.

Physicists and biologists alike are still trying to sort out all of the details; but we get the general gist of how it works and much of that knowledge has resulted in the air travel we enjoy today.

A bird in the air has two forces to contend with: gravity (the inexorable force the earth exerts on everything, drawing us back to its core) and drag (the force of the air that pushes back against us whenever we try to move through it). In order to keep itself aloft, the wings of a bird must produce enough lift to counter gravity and reduce drag.

 

Much of that is achieved through the shape the wing. It takes a lot of energy to flap all the time to produce enough thrust to keep you up and moving forward, so having wings that can generate lift and reduce drag as you glide are a beneficial adaptation. Wings aren’t flat, whether they are on a bird or a plane. Flat wings don’t create lift. Air moving around a symmetrical wing passes over and under its surface at the same speed on both sides. However, if you curve the wing and create a cambered airfoil, then you’re getting somewhere. With a cambered wing, the air passing over the top moves much faster than the air passing below the wing. This creates a pressure differential, with lower pressure above the wing, where air is being swept away and high pressure below where air is piling up, pushing the wing and the bird attached to it, up into the sky. There wasn’t much camber to my willow branches, hence the crash landing.

 

Another way increase that pressure differential is to tilt the leading edge of the wing up, dropping the flight feathers down and building up more air underneath. However, you can go too far with this. Tilt more than about 15o and the airstream separates from the upper surface of the wing, creating turbulence, stalling the bird out. They use this to their advantage when landing, like the gull in the image above. To control the stall, most birds can raise their equivalent of a thumb called the alula. This nub of bone with usually about three feathers on it (you can just see it sticking up behind the top of the gull’s wing in the picture) can split the airstream at the leading edge, forcing it back over the surface of the wing.

 

 

 

Once they’ve vanquished gravity, there’s still the matter of drag threatening to push them back to the ground. Flapping, of course, will keep you moving; but there are several design considerations that birds have made over millenia of evolution.  Birds that do a lot of gliding (e.g. gulls) have long, tapered wings that concentrate any vortices that might form at the wing tips (turbulence caused by the feathers slicing through the air) into two small areas that are as far apart as possible, reducing what is called ‘pressure drag’. Soaring birds, like hawks and Sandhill Cranes, take a different approach, spreading out their primary feathers like fingers, splitting up the wingtip vortices and reducing their impact.

If you found wrapping your head around all that was a bit of a challenge (like I did the first time I had to teach it), understanding what’s going on when a bird is flapping will give you a veritable headache. Things get complicated as the wing starts to move and lift and thrust start happening simultaneously. In a nutshell, however, the lift is generated by the curve in the part of the wing closest to the body, while the tips of the primaries produce the thrust, creating momentum that propels the bird through the air with a grace that always amazes me.

Sometimes taking a phenomenon apart and learning how each component works destroys the magic of the whole thing; but I haven’t found that to be the case with the flight of birds. Understanding the forces that make it possible for them to shed the earth’s shackles only makes it all the more remarkable.

Sounds of Silence

Walking through the winter woods I can’t help but feel an overwhelming sense of closeness with the world around me. Snow is nature’s greatest silencer, muting the world as it bathes it in white and it’s this silence that breeds a feeling of intimacy with my forest brethren. Shrouded by heavy bows and intermittent shadows, I feel my senses stretch through the quiet, reaching out for any sign that I’m not alone in my wanderings.

As I make my silent progress, I find myself wondering how the other inhabitants of the forest perceive this winter world. Whenever I get into one of these moods, my mind usually strays to the white-tailed deer, a species I’m fortunate to meet often on my woodland rambles.

We’re about the same size, a doe and I, and their soft, forward-facing eyes and expressive faces make them easy to relate to.

Though I know she could easily outrun me (especially since I’m a rather slow runner, even for a human), we have a bit more in common than we might first realize. White-tailed deer and humans perceive the world in much the same way. Deer, for the most part, are just a lot better at it.  They have to be. When you live you life under the constant threat of predation, it’s in your best interest to develop a sophisticated arsenal of early-warning systems and deer have plenty.

In deer, the nose knows everything that’s going on around them. With over 290 million olfactory receptors, deer can detect the faintest whiff of danger, even more accurately than their canine pursuers (who only have about 220 million). Both, however, seriously outstrip humans, with our rather paltry 5 million. Where do they put them all? The nasal region of both cervid and canine skulls is actually quite long and full of thin bones in a delicate scroll-work called nasal turbinates. In the living creature, these bones are covered with olfactory epithelium (skin with scent receptors) that picks up the tiniest of molecules. When actively sniffing, they fill their nasal cavities with as much air as possible, giving scent molecules a better chance of being picked up.

To further improve things, deer have a small, fluid-filled sack lying just on top of the palette called the vomeronasal organ (or Jacobson’s organ). This seems to function in a very specific type of scent detection – pheromones, something most mammals use in abundance and deer are no exception.  Whether we have such a functioning organ too is still being debated, but there is evidence that suggests it might play a subtle role in our lives.

Whenever I come face-to-face with a deer, I’m always drawn in by those liquid doe-eyes and this is one place where we have a bit of an edge over our four-legged friend, at least when it comes to how we see our world. Most people will tell you that mammals, especially ones that are active in the dark, don’t see colour. That’s not entirely true. The retina of deer eyes do have cones (colour receptors); they just can’t quite distinguish the same spectrum. A deer’s world is tinted in blues and greens, which makes sense, considering their main concern is picking out the right plants to eat. Still, don’t think you’re invisible to them as you walk through the woods in a blaze-orange vest. Recent work has found that they can pick out at least a hint of these longer wavelengths and with a visual range of 300 degrees while standing still and eyes that are highly sensitive to the slightest movement, a deer will notice you long before you even know you’re not alone.

Besides, if the eyes fail them, the ears wont. No matter how carefully I tread, I know that somewhere, the crunch of my footsteps is being collected by the large, rotating pinna of a deer’s ear. Their range of hearing is considerably better than ours, picking out much higher frequencies than we could ever hope to detect. The wide placement of the ears on the head and their ability to rotate them independently also make it possible for a deer to triangulate the source of a sound, much like an owl.

I know that I will never experience the world on the same level as any of my fellow forest inhabitants, but on a silent, snowy afternoon, I can’t help but want to try.

 

I’m Learnin’ to Fly

I’m always on the lookout for wildlife, even when I’m driving 100 km/h down a highway. My sister used to always get annoyed at my penchant for pointing out hawks circling overhead or braking suddenly to check out some mergansers along the lakeshore.

Well, the other day, my wandering eyes paid off. I spotted frantic flapping atop a hydro pole and had to pull over. It was definitely worth the stop, as I found myself watching a couple of juvenile Ospreys testing out their wings under the watchful eyes of their parents.

Over and over again they flapped furiously, gaining loft, but holding onto the branches of the nest like a ballerina would a barre. It was truly an amazing moment to witness.

Birds aren’t born knowing how do fly, just like humans aren’t born knowing how to walk. First off, it takes time to develop the enormous pectoral muscles needed to create and sustain the thrust required to get them off the ground and keep them in the air. Although most species lighten the load with hollow long bones and lungs that extend into air sacs throughout much of the body, the muscles responsible for flapping their wings make up 25-35% of a bird’s mass. These take time to develop; how much varies from species to species.  In Osprey, it’s nearly two months.

During that time, they practice, flapping and fluttering awkwardly and sometimes falling altogether. In some species, parents encourage the process by landing farther and farther from the nest with each food delivery, forcing their offspring to come out of their safe haven.

That fragile period in a bird’s life known as fledging is a bit of a behavioural tug-of-war between the demands of the young and the desires of the parents. It’s really not all that unlike human parents trying to get their grown up children to move out. Young birds don’t really want to leave the nest. I mean, why would you? You’re relatively safe, cozy and mom and dad bring you food several times a day. Sure, it gets a little cramped being crammed in there with your siblings and your room isn’t always the cleanest, but you don’t have to go out and work for your food. What’s not to love about that?

The thing is, parent birds need a break by the time young are ready to fledge. They can lose a significant amount of their body mass as a result of the energetic demands of feeding and protecting their offspring. Some species still have time in a season to raise a second brood, potentially doubling their genetic payoff. So, they want to get the kids off and into the world as soon as possible. Scientists have been studying this clash of wills for a long time now, measuring the costs and benefits on both sides of this ‘parent-offspring’ conflict.

When that conflict is resolved depends a lot of the species. Small songbirds usually only spend a couple weeks in the nest and then another couple of weeks following mom and dad around, figuring out how to feed themselves, but still begging for a handout whenever they can. For raptors, the period is much longer; osprey can take up to 17 weeks to become independent. It takes time to learn the art of hunting your own prey.

Young raptors learn by watching and again, through practice. I’m sure that for each generation of raptor there are mice and fish out there who’ve had a few years shaved off their lives from the terror of a near miss by a rookie owl or osprey careening towards them.

Still, they eventually get it right. They have to; at some point, mom and dad decide that they’ve invested enough into this generation and cut the chord. Because, regardless of the species we all must stand on our own two feet.

Time for a Cool Change

I’ve been getting regular updates lately about a ‘butterfly raising project’ and it reminded me of the one time I was lucky enough to witness this amazing event in nature.

I happened upon this White Admiral (Limenitis arthemis) last summer. I nearly tripped over it, at first unaware of what I had stumbled across. When I looked closely at this newly ‘hatched’ butterfly, drying its brand new wings, the whole thing took my breath away.

It’s a process we learn about as children, one of those uncontested facts that just lives in our brains: caterpillars become butterflies. However, that simple statement doesn’t even begin to do justice to what is truly an amazing process.

Insect life cycles encompass multiple stages that may involve fairly dramatic transformations from larvae to adult (like the previously celebrated fishfly). However, only a few groups of insects other than lepidopterans (butterflies and moths), such as bees, flies and beetles, undergo complete metamorphosis.

It’s a quite remarkable when you really think about it. These lumpy, worm-like creatures that lumber along, munching at leaves transform completely into delicate, colourful jewels that sip daintily at their food, the Victorian lady of the insect world. It happens at the pupal stage, when the larvae (caterpillars) form a chrysalis that then sits suspended for a few weeks up to a few years, depending on the species. From our point of view, it looks like nothing is happening, but on the inside, it’s a different story.

Like most things in animal physiology, the whole process boils down to hormones, the transformation being dictated by the relative amounts of two chemicals coursing through the critter’s hemolymph (insect blood). Just like every other insect, caterpillars moult, shedding their exoskeleton to make room from their growing bodies. Each moult is governed by a hormone called ecdysone (stemming from the word ecdysis, a fancy word for moult). Each new shed produces a larger caterpillar as long as a second hormone called juvenile hormone (thankfully, self-explanatory) is also circulating. It’s basically a chemical that tells the caterpillar to stay a caterpillar.

Then one day, often as a result of changing day lengths or temperature, the caterpillar’s body stops making  juvenile hormone, so when the next moult comes around, things change, the chrysalis is formed and ultimately a butterfly emerges. But how does it go from a wiggling lump to something as complex as a butterfly? Well, that lump was carrying around little spheres of tissue called imaginal discs. These discs truly make the imagined possible, the cells differentiating into eyes, antennae, wings and legs. Each disc has it’s own part to build and if you were to move it to another place on the caterpillar you’d end up with a Picasso painting of a butterfly.

Once the process is complete, the chrysalis splits open and the new adult rests for a bit, drying its wings until it can safely take flight.  The transformation doesn’t only affect what the insect looks like; it’s a complete life change. The metamorphosis from caterpillar to butterfly is a transition from the feeding stage to the reproductive stage and in many cases, that transition is absolute. Luna moths, for example, are like fishflies; once they reach the adult stage, they can no longer feed and their sole purpose is to mate in the day or so they have left before their metabolisms burn out. Of course, not all lepidopterans are as short-lived as adults. Some, like the Mourning Cloak actually hibernate at the adult stage, while Monarch adults travel thousands of kilometres.

So, why go through all that trouble? Why not stay a caterpillar? I’m not sure there is a definite answer to that and I’m sure it’s fuelled many debates among evolutionary biologists. Personally, the fanciful side of me likes the idea that a caterpillar decided one day that he wanted to fly. I think we all have days when we wish to break out of our shell and I think a little change, now and then, can be a good thing.

We’re here for a good time, not a long time…

If you’d told me 20 years ago that I would be writing a piece extolling the virtues of the fishfly, I would’ve told you that you were crazy. As a child, I tried to get out of going to the cottage during the first few weeks of July, simply to avoid having to deal with these large, awkward insects that appeared in the thousands and stuck to everything. I would go to great lengths to avoid coming in contact with them and I couldn’t stand the smell that hung over the beach during those weeks that their bodies washed ashore, creating a putrid line in the sand.

However, here I am, much older and hopefully wiser, and an unapologetic fishfly fan. It was when I returned a few years ago to live alongside our great lake, that I discovered just how remarkable these insects truly are.

Whether you call them fishflies, mayflies or shadflies, these large-winged, long-tailed insects belong to the order Ephemeroptera, which literally means: ‘things with wings that don’t live very long’. It’s a fairly apt description if you only consider the adult form. With vestigial mouth parts and a digestive tract full of air, they’re lucky to last for more than a day. However, if you take into account the insect’s entire life cycle, they are actually relatively long-lived.

Here on Lake Winnipeg, our fishflies (mostly Hexagenia limbata) spend about two years as nyads (larvae), living in the sandy bottom of this immense, but shallow body of water. They’re detritivores, feeding on algae, diatoms and other bits and pieces that find their way to the bottom. They, in turn, form a large part of the food base for the numerous fish species that fill the lake.

Then, somewhere around the first week of July, an instinctual switch is flipped, sending the two-year-old nyads to the surface. Floating in the meniscus of the lake, their backs split open like a seam, letting the newly-formed winged morph  emerge. This stage is call the subimago and unlike any other order of insects, they’ll moult one more time into fully-fledged adults, all in the space of about a day.

It’s not so much the process that makes them remarkable, but the numbers. Lake Winnipeg, like many other shallow, fertile lakes and river systems, is home to millions of fishflies and they tend to show up all at once, carpeting everything: walls, roads, mailboxes, trees, lampposts, anything that’s standing still long enough for them to stick to. This mass emergence is their way of shuffling the genetic deck. It’s a nocturnal orgy of mating and egg-laying before everyone literally drops dead, their tiny bodies piling up under lights and along the beaches to be cleaned up by hoards of hungry gulls if the towns along the lake don’t get to them first with the front-end loaders.

Most people anticipate this yearly irruption with fear and distaste. I, on the other hand, look forward to it, because as long as there’s fishflies, Lake Winnipeg has hope.

Our lake is in trouble. Like way too many watersheds around the world, it is suffering from too much of a good thing: nutrients. An overabundance of phosphate and nitrogen are finding their way into the water, fuelling giant blooms of algae that, among other things, reduce the oxygen content of the lake both by using it themselves and by keeping it from reaching the bottom, where the fishflies live.

I fear for a fishfly-free summer. Thankfully, we’re not there yet and I’m optimistic that we can still turn the tide. Algae levels have been increasing for years, but public awareness has also risen and steps are being made to improve waste water treatment and watershed management. We have a very long road ahead, but as long as I keep finding fishflies stuck to my windows every summer, I’ll believe we can make it.

Snakes on a Plain

Our month of change is coming to a close. May is an amazing month out here. In the space of only a few days, we witness a stunning transformation. In the blink of an eye, we manage to go from a barren landscape, just recovering from the ravages of a northern winter to a lush and verdant pastoral scene. Everything wakes up in May. Buds that have been straining against their confines finally burst free, the air fills with the scent of fresh pollen and the busy sounds of returning birds. Insects emerge from their hiding places, crawling out into the newly warm sunshine, but they aren’t the only creatures to find their way out of the darkness.

Up in my neck of the woods, we get to witness something truly remarkable. Every May in central Manitoba is marked by the emergence of the largest concentration of snakes in the world.

In a nondescript piece of prairie and aspen parkland, over 50,000 red-sided garter snakes (Thamnophis sirtalis parietalis) emerge after a six month sleep from large caves in the limestone bedrock, bringing the underbrush to life with their constant slithering.

So what makes this nearly 12,000 hectare bit of scrubland snake mecca? As they say in real estate: location, location, location. It’s not the habitat above the ground that counts, but what’s below it. Much of central Manitoba is underlain by layers of limestone and dolomite, dating back 300 to 500 million years ago.  Limestone can be dissolved by water and over time, it has eroded away large hollows in the area, creating a formation known as karst topography.  You can find crevasses and caverns of different shapes and sizes all over the Interlake region. I have quite a few further north in the forests I call home, but none are quite as large as the network of five caverns that crisscross under the Narcisse Wildlife Management Area.

They’re also pretty deep, stretching down below the frost line, which is what makes them so attractive to snakes, because unlike many other cold-blooded critters, snakes don’t keep well in a freezer. So, after waiting out the worst of the cold, their internal clock tells them it’s time to wake up, sending the snakes up to the surface.

When that happens at the Narcisse dens, it’s a sight to behold: thousands of snakes, milling about in the dens and and

Red-sided garter snakes at the dens in Narcisse, Manitoba

surrounding areas. They stick around for almost a month after they first glimpse the sunshine because this is one of the few opportunities for this otherwise solitary creature to mix up the genetic pool. As soon as they emerge from the dens, females are literally pounced upon by dozens of males, forming something biologists delicately describe as a ‘mating ball’. Males jockey for position, trying to be the one to get his sperm to the eggs. Because females can store the sperm before fertilization, it’s likely her young end up being the product of more than one father.

By the end of May, however, the furor dies down. Knocked up and ready to go, both males and females disperse to spend the summer feeding and, in the case of the females, giving birth. The dens and other hibernacula sit empty for the summer, but as the song says, we’ll see them in September.

Coming out of the Woodwork

Spring is sort of a fickle thing around here. I was so sure we’d seen the last of the snow, then I woke up to white and howling north winds over the weekend. The only saving grace was that it didn’t last for long.

Weather isn’t a very reliable indicator of the seasons up in the north woods. I’m pretty sure the only month I haven’t seen flurries of some kind is July. However, there are plenty of other indicators of the impeding spring.

While returning birds are always a good sign, it’s when I see my first butterfly that I know we’re finally starting to thaw for the year. Usually sometime around early April, I spot one, a Mourning Cloak (Nymphalus antiopa, pictured) or an Eastern Comma (Polygonia comma), basking on a branch or the middle of a gravel road, soaking up the now warmth-giving rays.  It’s always an especially fun juxtaposition when I find one sitting on top of some snow that just refuses to melt and it makes me wonder: what is a cold-blooded insect doing up and about so soon in the spring?

The reason these butterflies can get an early start on things is because they spend the winter hibernating as adults. Actually, calling it hibernation is putting it lightly. They tuck their delicate bodies into old woodpecker holes, cracks in the tree bark or between the shingles and wall boards of old or unheated buildings and then they simply let themselves freeze. Okay, well not quite. While they do let ice invade their bodies, these butterflies are quite particular about where the crystals form, keeping them confined to the fluid on the outside of their cells so that vital systems aren’t destroyed.

As the days get longer and warmer, they literally come out of the woodwork, flitting around in the sunshine, even when there is a foot of snow on the ground. How these butterflies and other freeze-tolerant organisms know when to wake up is still a mystery. They’re basically in a state of stasis all winter, their lives set on pause, so what exactly constitutes their alarm clock is still an unknown.

Once they’re up and at it, however, there is no time to waste. Mating begins right away, with males and females fluttering around each other before settling down to business. Once the eggs are laid on suitable host plants, like willow, aspen and birch, these harbingers of spring die off, leaving their genetic legacies to the next generation. It may seem like a short life, but most of these over wintering butterflies have been alive as adults for up to 10 months, veritable ancients for their world.