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.

 

 

 

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.

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.

Sweetness and Light

Portrait of Fireweed by Heather HinamThe first blush of spring flowers has long since faded, leaving forests and fields to settle into the rich greens and sunny yellows of mid-summer. Still, the decidedly verdant palette is broken now and then by a showy splash of pink, startling against the endless green, like flame in the darkness.

These tall, fuschia spires are fireweed, nature’s phoenix, rising out of the ashes of destruction and bringing colour back to the land. They also happen to be one of my favourite flowers; but not for a reason that’s immediately obvious. They’re actually rather tasty.

Nearly 15 years ago, I was fortunate to spend some time visiting a friend in the Yukon. We had an amazing time exploring the western edge of the territory, camping out in the shadow of the Rockies in the still long days of early fall.

In the airport on the way home, I spotted it, jars of a clear pink, gleaming in the fluorescent light of the gift shop: fireweed jelly. I had to try it and after tasting its delicate, sweet flavour, I had to figure out how to make it.

Turns out, the second part of that equation was harder than I expected it to be. Over 10 years ago, the internet was not as vast and I couldn’t find a recipe anywhere. After much searching, I ended up finding what I needed in a dusty old text squirrelled away in the Winnipeg public library.  I actually found a lot of ways to cook wild edibles in that book; but most coveted was my recipe that will work for any petal-based jelly.

We’ve been blessed with an abundance of fireweed this summer in Grindstone; but I’ve been so busy with other work that I haven’t had time to go out and harvest. It’s fairly time-consuming labour. Picking the flowers is easy enough. You just need a pair of scissors, long pants and something to store the feathery spikes in. Once you get them home, the fun part starts: separating the blossoms from the stem. I usually end up spending a good hour plucking the flowers, one by one, dropping them into a bowl and setting the green bits (which are also edible) aside. By the end, your fingers will be died purple and the rest of you will be crawling with crab spiders and leaf hoppers; but it will be worth it in the end, trust me.

Once you have your blossoms, stuff as many as you can into a pint sealer jar and cover the lot with boiling water.  Let the developing tea steep for 24 hours in a dark space (to keep the sunlight from washing out the delicate colour). Strain out the now leeched-white blossoms and pour the liquid into a deep pot, adding 1 1/2 cups of sugar for every cup of tea (3 cups to a pint). Add a teaspoon of lemon juice and bring to a rolling boil, letting it go for a good minute. Add 6 oz of liquid pectic to the mix and boil hard for another minute or so. Take it off the heat and skim any foam before carefully filling sealer jars and proceed to can it according to direction.

This recipe doesn’t make much, but it’s flavour is worth it. If you’re concerned about the colour once you’ve strained out the blossoms (sometimes it can look a little brownish), you can add a tablespoon or so of strawberry juice. It won’t affect the taste, but will keep it nice and pink.

Fireweed is one of those flowers that just seems designed to bring joy wherever it grows. As suggested by its name, its rhizomic habit makes them one of the first colonizers to bring colour back to a fire-blackened forest, springing up through the ash from runners in the underlying soil.

This year, the bright blossoms brought beauty back to the devastation wrought by Manitoba Hydro after they cleared the area around their power lines of shrubs and trees in my area. As my friend, Cindy mentions in her recent post on the same subject, thanks to their tenacious rhizomes that can knit their way through the soil up to almost half a metre deep, fireweed managed to find its way into the centre of London after the city was ruined in places by World War II bombs. To me this hardy denizen of northern forests and fields is a reminder to all of us that even in the face of humanity at its ugliest and most destructive, nature always manages to find a way to bring light back to the earth.

Bright-eyed and Bushy Tailed

Red squirrelAfter charging out of the gate early and then several false starts later, spring is finally settling in here in the boreal forest.  It’s been a strange year so far and I can’t help but wonder worriedly at the changes I’ve been seeing in the climate these last several years.  Between summer-like temperatures, then snow and frost, it’s been hard to get true sense of the seasons.

The animals, however, tell a different story. Seasonal behaviour in most species is hard-wired to a certain degree, often tied in less to temperature and more to changes in the length of daylight.  While, unseasonably warm or cold days can either speed up or slow down nature’s clock, the overall pattern remains relatively constant.

For me, one of the first harbingers of spring comes in the form of a frantic ball of red fur streaking through the forest.  Red squirrels (Tamiascurius hudsonicus) are active all year, racing from tree to tree, industriously gathering up anything remotely edible and either devouring it on the spot or stuffing it away in a midden, the heart of their territory, for leaner times.

This flurry of activity takes a definite upturn as the darkness of winter gives way into the softer, longer light of spring.  Here in the boreal, that can be as early as the beginning of March, when patches of snow-free ground begin to appear on the forest floor. Females are only reproductively receptive for a day, but she’s not shy in giving her potential suitors a head’s up, bounding through their territories, days before her estrous, reminding them of their impending opportunity.

Squirrels aren’t known for their social grace or a warm and welcoming demeanor. These feisty little rodents are fiercely territorial, expressing their displeasure at anyone and anything that crosses into their domain with an insistent rattle that ricochets off the surrounding trees like a miniature jackhammer. Mating season is the only time of year that edginess eases somewhat and males welcome the presence of female intruders into their little patch of forest, hoping for a chance to pass on their genes. However, if another male crosses over the boundary, all bets are off and the territory holder immediately lays into the interloper, the two of them bounding through the forest in a flurry of fur and furious chattering.

Females are equally antisocial and once the deed is done and she’s been inseminated, the donor is no longer welcome on her doorstep. Like many mammals, red squirrel females raise their young on their own, tucking themselves away into an old woodpecker hole to set-up a home for their young.

Gestation is only a little over a month, so it won’t be long before the squirrels in my neighbourhood find themselves with new mouths to feed. The young are born blind and pink, completely dependent on their mother’s milk and warmth, tucked up in the whorls of grass with which she’s lined their nest. Nests are established opportunistically, and squirrels will just as easily set up house in a nest box intended for birds as in a natural cavity. In my years working with saw-whet owls, I’ve stuck my hand into my fair share of squirrel’s nests and come out with a palm full of very warm, very naked little babies.

They grow quickly, however, putting  on almost 2g/day until they’re ready to venture out on their own just over four months later. By that time, the little guys are fully furred, smaller replicas of their parents, with an innate ability to scamper through the trees without a second thought. That’s not to say there isn’t a bit of a learning curve. One can only marvel at their resilience when watching a juvenile plunge 40 ft out of the tree to the ground, dust himself off and climb right back up like it was nothing more and a stubbed toe.

Resilience is key if you’re a red squirrel. Once they leave the nest, times are tough. By the end of the summer, they are no longer welcome on their mother’s territory and must take up residence someplace else. Competition is fierce and predators, like marten, goshawks and owls are just waiting to make a meal of them. Still, squirrels are scrappers and if they can get a foothold in that first year of life, they’ll likely be just fine. So, spring settles in with fits and starts after an unnervingly warm winter, I can’t help but take comfort in the ringing rattle outside my window, reminding me that even with all that is changing around me, the seasons still cycle and life finds a way to move ever forward.

Feed Me, Seymour

I have to admit that plants are not the first things that come to mind when I think of the word carnivore. However, after spending a morning mucking about in a peat bog last week, I was reminded that ‘meat-eaters’ can be found in pretty much any kingdom and  like their animal counterparts, carnivorous plants can be as beautiful as they are deadly.

In the boreal forests of Manitoba, pitcher plants (Sarracenia purpurea) are probably the most commonly encountered carnivorous plant. If you happen to stumble into the right habitat, they can be downright plentiful. We found dozens of them springing up from the carpet of sphagnum, looking like the bloodied tubes of an expansive green pipe organ.

These plants are truly a wonder of evolutionary design. The pitchers are modified leaves, curled in on themselves and fused to form a vessel that holds rainwater. The fluted edges are boldly pattered to be attractive to insects. However, what an unsuspecting bug doesn’t realize is those leaves are also covered in stiff, slippery downward-pointing hairs. When an insect lands on the rim, they immediately head for the mouth of the pitcher, in search of the nectar promised by the bold colours of the plant. However, the deeper they go, the more difficult it becomes to retreat. The hairs only go one way, drawing their quarry down into their watery doom. The ill-fated arthropod eventually drops into the water and ultimately drowns, its decomposing body providing much-needed nutrients for the plant.

But what would drive the evolution of such a set-up? Most plants are more than capable of feeding themselves, transforming carbon dioxide into energetic sugars through photosynthesis and drawing nutrients from the substrate they’re growing on. For pitcher plants, the big problem is finding enough nitrogen to grow and reproduce. Bogs are cold, acidic places and nitrogen is hard to come by. However, bogs have a lot of insects, flies, mosquitoes and all sorts of critters flitting about, their little nitrogen-filled bodies just there for the taking.

So plants, like pitcher plants and sundews have evolved a way to take advantage of the situation and as a result, thrive in an environment where many organisms could never get a footing and those that do only manage to barely eke out a living.

Although they may be hardy and can go where few vascular plants have gone before, pitcher plants are still vulnerable. Bogs are fragile ecosystems, often taking from decades to millennia to form. Forestry, oil and gas exploration, wetland draining and peat harvesting destroy these habitats, often permanently. The good news, however, is that in part because of just how hard most boreal wetlands are to get to, there are still over 100 million hectares of peat bogs and fens in Canada.

Most of us don’t realize just how important these regions are. These often bleak-looking stretches of greens and browns that wrap around the boreal belt can store on average 3.5 times more carbon per hectare than the forests that surround them. They also hold vast volumes of water, slowing run-off and filtering out pollutants from watersheds. Although Canada’s peatlands are still relatively intact, the world has already lost over 25% of these wetlands to agriculture and harvesting in a number of countries, releasing tonnes of CO2 into the atmosphere and changing water dynamics. It’s a slippery slope. We’re on the lip of the pitcher plant. If we as a species don’t pull back hard on the reins of our need for carbon and other natural resources, more of these valuable sinks will be lost and we will find ourselves tumbling down into our dark pool.

So, put on your boots and venture out into these wet and wonderful places. Admire the pitcher plants and other unique organisms that call this seemingly desolate place home and remember that just because something’s beautiful doesn’t mean it’s not dangerous and sometimes that which seems dull and ordinary is often extraordinary.

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.