Flight of the Bumblebee

Bumblebee pollinating fireweed by Heather HinamIt’s been a long, long, long winter here in the north woods. Then, suddenly, it was summer. The browns and greys of last year’s decay vanished nearly overnight, replaced by the verdant greens of new growth. Flowers are coming up everywhere and the air is alive with insects. That last part doesn’t get most people up here all that excited. A large proportion of those insects at the moment are mosquitoes. However, trundling along through the clouds of bloodsuckers are the pollinators.

One of my favourite groups of the myriad species that call this region home are the bumblebees (Bombus sp.), the flying teddy bears of the insect world.  While most members of the Order Hymenoptera, like wasps and hornets, tend to send people running in the other direction, bumblebees hold a special place in the hearts of even the most nature deprived. Their brightly-coloured, fat, fuzzy bodies, topped with almost comically small wings, coupled with their almost roly-poly nature makes even the most hardened insect-hater melt a little bit on the inside.

Unlike honeybees, bumblebees are native to North American. There are a few dozen species that have fit into just about every niche across the continent, making up what may be the most important assemblage of pollinators we have.  What makes them so efficient at the job is their hairy bodies. Bumblebees feed on nectar and that is usually stored near the centre of the flower. As the bumblebee noses its way deeper into the blossom, the pollen-laden stamens brush against the insect’s body, transferring its important cargo to be transported to the next blossom.

While they do collect that nectar, bumblebees are not honey producers. Unlike the species we’re mostly familiar with, bumblebees are only semi-colonial, setting up small nests that only last for one year. It all starts once the frost is out of the ground. Queen bumblebees overwinter by themselves in the leaf litter or underground. Once she wakes up, her first order of business is finding food. With the late winter we had this year, she likely would’ve had a harder time than usual.

Once she’s managed to restore her energy levels, the queen will set up shop in a quiet, dry place like a woodpile, old rodent hole, tree cavity or even a nestbox. There, she will lay her first clutch of eggs, which she’s incubates in the most adorable fashion by sitting on top of them and ‘shivering’. To feed herself and her young larvae once they hatch, the queen gathers nectar that she stores in her nest in little wax pots.

That first generation of bees are all worker females, who quickly take over the foraging duties, bringing home more nectar and fashioning more wax pots, upon which the queen lays her subsequent eggs. Workers also take on guard and cleaning duties while the queen remains in the nest, taking a well-deserved rest and generally ruling the roost.

As the long days of summer begin to wane, the queen plans her insurance policy for the following year, laying eggs that hatch out both males and new queens. Both of these cohorts leave the nest and somehow find each other in the big, bright world outside of the colony.

Once mated, those new queens head off to find a place to hunker down for the winter while the home there were born from fades away.  It’s a system that’s worked for thousands of years, ensuring the proper functioning of pretty much every ecosystem in North America. Unfortunately, now, it’s in trouble. Like most pollinators, bumblebees are facing hits from all directions. Losing both nest and food sources to habitat loss from large-scale agriculture, timber harvest and urbanization, they are also having to contend with pesticide usage turning the plants they depend on into death traps.

However, if we, as a populace, make a conscious effort to change the way we do things, curtailing bee decline is not an insurmountable problem and every individual counts. By planting bee-friendly species in your yard that come from growers you know don’t use pesticides, you’re creating a haven for these beleaguered bugs. Talk to your greenhouse owners, talk to your representatives. There’s more and more data showing that certain types of chemicals are the problem and need to be taken off the shelves and out of our food production. We’ve done it before with DDT. We can do it again.If we don’t, the world as we know it will cease to function. It’s as simple as that.

For those of you who are a little less insect-inclined, it’s also good to remember that bumblebees are nothing to be afraid of. While they can sting, they’re pretty mellow individuals and if you take precautions like not wearing strong perfumes and running around barefoot, you’ll have no trouble co-existing peacefully with these fuzzy, buzzing, beautiful and essential bugs.

 

 

 

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Back Home on the Range

Plains Bison and Keystone Species by Heather HinamI’ve fallen behind a bit on my posts of late; but in my defence, I’ve been very busy teaching and for the first time in a while, travelling.

In my travels, I had the opportunity to branch out from my usual boreal forest/aspen parkland region and explore a whole new host of habitats.

One of those were the grasslands of southern Saskatchewan. These regions are often passed over as ‘boring’ by travellers in Canada who prefer the more obvious grandeur of the Rocky Mountains or coastal regions.

However, I can assure you that the mixed-grass prairie that carpets a swath along Canada’s border with Montana is a truly remarkable region, full of breathtaking beauty and a whole host of fascinating species you won’t find anywhere else.  The stark landscape is alive with grasses rippling in waves, dotted with islands of sagebrush, the odd tree and the carefully manicured lawns of prairie dog towns.

This is the landscape that once was home to the plains bison. For thousands of years, millions of these thundering ungulates roamed not only grasslands, but at least 45 other ecoregions as the largest-ranging ungulate in North America, shaping each region as they went. You see, bison are what are known as a keystone species.

Keystone species are those whose impact on the world in which they live is greater than what you’d expect from its population or, more specifically, its biomass. These are species who fundamentally alter the habitat they live in, affecting the lives of myriad species around them.

In their heyday, these largest of all North American herbivores were the linchpin holding the grassland ecosystem together, providing food for a host of predators, including entire civilizations of humans and by shaping the very structure of the landscape and thus affecting the day-to-day lives of a large proportion of prairie species.  I was fortunate to learn about these relationships from Wes Olson, former Parks Canada warden who has lived and worked with bison for decades.

Bison literally left their footprints on the landscape. Their heavy bodies pressed their hooves into the earth, leaving singular holes (called pugging) that bled into trails, churning the soil and breaking up the thatch from previous years for new growth and allowing a greater diversity of plants to get a foothold. Ploughing their noses through the winter snow to graze the coarse remains of the summer’s grass left short-cropped lawns that would green up faster in the spring, offering much-needed nutrients to both the bison and other prairie grazers like jack rabbits and pronghorn. These patches also would get a boost of nitrogen from urine the bison released regularly into the ground.

These winter grazing lawns were also great places for animals that need visibility to congregate. Birds like Sharp-tailed grouse and sage grouse could use them in early spring as dancing grounds, or leks, where males get out and literally strut their stuff in the hopes of finding a female.

A bison’s penchant for wallowing also had a significant effect on the landscape. When a 2000 lb animal rolls around on the ground, it tends to leave a mark. These dust bath pits were often the only spots on the prairie to retain open water for any length of time and become important draws for many dozens of species from insects and frogs to top carnivores like badgers and coyotes.

Every part of the animal was used. Human predators, like the Blackfoot people of southern Alberta would use everything from the hide to the meat to the bladder for protection, food and other tools. Animal predators, like coyotes would feed on the flesh. Scavengers, like vultures and badgers, would take what was left. Rodents would gnaw on the bones in their search for the calcium missing from their diets. Dung beetles and burrowing owls would make use of the bison patties for food and olfactory camouflage respectively, if humans didn’t scoop them up first for fuel in this wood-less landscape.

This intricate network was torn apart as European settlers moved across the continent. By the late 1800s, a combination of habitat loss, conscious extermination efforts and just plain wastefulness saw a population of several million reduced to tiny, isolated herds. Today, the wild population numbers about 30,000 individuals, restricted to parks and conservation areas.

However, the bison is not extinct and the threads are starting to re-knit themselves in more and more places. Herds have been thriving in Elk Island and Riding Mountain National Parks for years, making their mark on the aspen parkland. Plains bison were also reintroduced to Grasslands National Park in southern Saskatchewan in 2009 and already their effects are being felt. Slowly, after over a century, this much-abused landscape is starting to heal. Though it’s hard, if not impossible to turn back the clock, some of the interactions and relationships I’ve described are reforming and places like Grasslands remind us just how complex and resilient nature really is.

A Thing With Feathers

Feather by Heather HinamEven 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.

Writing in the Snow

Qali Growing up, I would hear people quote this statistic: “Eskimos have more than a hundred words for snow.” Actually, I still hear people rattle off this little ‘fact’, especially in winter.  However, there are a lot of problems with this statement, not even including the fact that the indigenous people of North America’s tundra and Arctic regions are known as Inuit, not Eskimo. No, what really grates on me about this blanket statement is the implication that it’s somehow weird to have so many words to describe one thing.

When it’s something that makes up a very large part of your daily life during a significant portion of the year, why wouldn’t you take the time to describe it as accurately as possible? The English language has several words for rain: showers, downpour, drizzle, sheets, so why not snow, especially in light of the fact that it sticks around a lot longer than its warm weather counterpart.  Actually, as a Canadian, I’m surprised that we, as a population, haven’t developed more words beyond flurries, blizzard and slush to describe this white stuff that blankets much of the country for four to six months out of the year.

To do that, we have to turn to other cultures and languages. While the true count is well under one hundred, many Inuit dialects have several useful words to describe the incredible variety of snow that we can encounter throughout the course of the winter.  For those of us who live in forested areas, one handy word to know is qali. It refers to the snow that builds up on the branches of trees, glazing limbs in white and making it look like someone attacked the woods with a decorator’s bag full of royal icing.

I was lucky to have learned several Inuit terms for snow as part of some of my undergraduate university courses and like many people who study winter ecology, they’ve been part of my lexicon ever since. So, it took a bit of digging to figure out where the word qali comes from. According to William Wonders, who wrote the book Canada’s Changing North (2003), the word originates from the Kobuk Valley Inuit of northwestern Alaska, along the edge of the treeline.

Qali can range in thickness from a light dusting that could almost be mistaken for hoar frost to heavy globs of wet snow that drag beleaguered limbs to the ground under its unrelenting weight. All along that spectrum, it has a significant impact on the ecological community.

Many winter residents are affected by qali. Spruce grouse and squirrels that regularly feed on cones often find themselves driven down to the ground by a particularly heavy layer of qali. The snow-covered branches can be hard to navigate, forcing these species to search elsewhere for food. On the other hand, qali can make some food more accessible. With particularly heavy wet snows, the qali that builds up on young birches, willow and aspen pulls the flexible branches down, bringing the young, tender tips within reach of hungry cottontails and snowshoe hare. These contorted trees may also provide shelter for a whole host of wildlife.

You might not have ever realized it, but if you live in an area that experiences snow, qali has likely affected you at some point and I don’t mean that moment when you accidentally brush up against a laden branch and send an unwanted shock of snow pouring down the collar of your coat. I’m talking about more significant impacts. Qali can be very heavy and often trees buckle under the weight taking down whatever else is nearby, which is some cases are power lines. I know I’ve spent the odd cold, snowy night in the dark, waiting for hydro to be restored.  These qali-broken trees also open up the forest floor to new growth, creating pockets of mini forest succession and driving the forest cycle on a smaller scale.

Snow is an amazing thing and qali is only one small facet in a dizzying array of diversity, which thanks to northern cultures, we’re able to describe in accurate and imaginative ways. So, next time you take a winter walk surrounded by white, take a moment and discover that variety for yourself and maybe even create your own words to describe it.

 

In the Bleak Midwinter

Insulation - chickadee warming its feetIt 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. Countercurrent Heat Exchange System in a bird's leg. by Heather HinamWarm 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.

Living on the Edge

Ecotone - a zone of transition, of overlapOur world is in a constant state of transition, both in time and space. Most of us are more aware of the former, noting the passing of minutes, days and years. However, for many species, it’s changes in habitat across space that have a significant impact on their survival.

Life needs edges, places where the shadows of the forest recede in the face of the sun, where waves of grasses dip their roots in murky waters, where ripples lap incessantly at a rock face, etching away the sand of the future. Edges create variety and when it comes to ecology, variety is truly the spice of life, at least in terms of its diversity.

The technical term for a transition zone between two types of habitat is ecotone. It’s a place where two communities meet, knitting together elements of each other, often bringing the best of both worlds.

Some ecotones are abrupt, like the striking boundary between forest edge and farmer’s field, a change so sudden, it can easily be seen from the air. Others are more gradual, such as the subtle gradation of shades from soft, sunny aspen leaves to the dark mossy needles of the boreal forest as one moves pole-ward throughout much of the northern hemisphere.  Some edges we we can’t even see, like the lines between distinct communities layered on top of each other in the depths of a lake. It’s all a matter of perspective. What might seem like a continuum to us, may be a stark contract to another species.  It all depends on the resources you value.

Regardless of how they’re defined, edges are important places. They’re interfaces, areas where two distinct worlds can influence each other for better or worse. Edge-effects can be positive or negative, depending on the organism whose point of view you are looking from and what type of edge it is.

Naturally occurring ecotones, like a reed bed bordering a lake shore, are hugely important areas, a bridge between the land and watery worlds, creating an interface where a greater number of species can thrive than would otherwise exist without these marshes. Whether they’re lines of trees along a winding stream, offering a windbreak in an otherwise open field, or a wet meadow cutting its way through a thick forest, edges can also provide natural thoroughfares, ancient pathways followed by generations of animals.

However, that same linear accessibility can also become a problem when the edge is not natural. Clear-cuts slicing into an normally intact forest, seismic lines cross-crossing though arctic tundra or farmland pushing into what’s left of tall-grass prairie can create novel and unnatural ecotones, opening corridors for predators and invasive species, irrevocably changing the landscape. In contrast, what may be right-of-ways for some organisms may also be barriers for others, with human-caused edges limiting normally wider-ranging movements of many habitat-sensitive species, such as songbirds and woodland caribou.

Anyway you cut it, the world is full of edges, both dividing and uniting this remarkable patchwork of landscapes in all three dimensions. Understanding the depth of that complexity and our impacts on it has kept biologists busy for decades and will continue to do so for many more to come. I, for one, welcome the chance to continue the exploration.

Restless Heart

Zugunruhe - migratory restlessnessTo regular readers of this blog, my love of obscure words is not a new thing. Over the last few years, I’ve been creating these ‘definition images’ as my way of bringing life to some of the wonders of nature and the words used to describe them.

Looking back over them all, I realized, much to my surprise, that I’ve crafted more than 70 of them, covering just about every letter of the alphabet. That discovery has led me to challenge myself to visualize words starting with more uncommon letters, like  X, Qand Z. Kind of like an artistic variation on Scrabble.

Autumn has given me the perfect opportunity to address one of my favourite Z words.  It’s another one of those terms that comes up only in the discussion of natural history and animal behaviour and it never fails to raise a few eyebrows if you manage to slip it into regular conversation.

The word is Zugunruhe.

Zugunruhe is a combination of two German words = Zug, meaning to move or migrate and Unruhe, meaning restlessness and it together, the sum is really the combination of the parts: migratory restlessness. For a behavioural ecologist, it’s a word that tends to conjure up thoughts of autumn, or more specifically, late summer.

As the earth lumbers along its orbital path and those of us in the Northern Hemisphere find ourselves canting away from the sun’s warmth, many creatures get antsy. Birds especially are seized by a sudden disquiet and activity levels skyrocket. Sleep patterns change and if the individuals are kept in a cage, they start orienting their activity in the direction they should be migrating in. Most species go through a period of excessive feeding, needing to pack away as much energy as aerodynamics will allow for the journey that inevitably lay ahead. We see it all around us in the clouds of blackbirds roiling through the air or flocks of geese descending on a recently-harvested field. This period of restlessness is referred to as Zugunruhe by biologists who study animal behaviour and it’s a phenomenon observed both in the spring and in the fall, just prior to the mass migrations that move millions of birds along north-south flyways over the continent.

Here, in the boreal forest, it’s a phenomenon that usually starts in August. Our summers are relatively short and as soon as breeding is over, the preparation of the twice-yearly journey gets underway, especially in songbirds, who have to travel thousands of kilometres to Central and South America. With their time here so fleeting and the journey so long and fraught with danger, you can’t help but wonder, why go through all the trouble?

Why not stay in the tropics, where the weather is favourable and save all of the energy and risk associated with long-distance travel? The answer to that question likely varies to a certain degree between species; but evidence suggests that food, or rather the lack of it, was likely the driver behind the evolution of long-distance migration in many birds.

Most of today’s migratory species likely evolved near the equator, enjoying consistently tolerable weather and relatively abundant food. However, as populations started to grow and segment into different species, the pressure on food sources grew to a point where the survival of some depended on searching out new resources. The only place to go was away, into the temperate zones north and south of the tropics. Those that did, discovered abundant resources, millions of insects, and a glut of fruit and vegetation. The problem was it only lasts for a short period of time, forcing those explorers to retreat back to the warm haven to the south during the winter months.

Over millenia, these paths have been extended and entrenched by generations of birds winging their way along now well-established routes.  As those paths have become increasingly ensconced in the collective memories of each species, so has the irrepressible need to travel those routes that spurs everything from hummingbirds to harriers on their way twice a year.

With migration in full swing here in Manitoba, the period of zugunruhe is actually over; but once balance of night and day swings back into the favour of the light, the millions of birds enjoying the warmth of their winter homes will feel the inexorable pull once again, the restlessness building until one day, they’ll have no choice but to take to the air and find their way back to us.