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.

Advertisements

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.

 

Moonlight Becomes You

Luna Moth by Heather HinamSome childhood memories just seem to stick with you, lodging in your grey matter and coming back to haunt you at random intervals.

One that has been showing up quite frequently on the mental playlist lately harkens all the way back to a stint at Girl Guide Camp at Bird’s Hill Park, just northeast of Winnipeg over 20 years ago. It was a dark and muggy mid-June night as we trucked off as a group of giggling girls to the public washrooms. In the orange haze of the sodium lights, we heard a shriek of fright and immediately thought a bear had found its way into the campsite. Nervous, we crept around the corner toward the source of the sound and found girls from another troupe cowering under the lights over the door, pointing to the wall.

The source of their terror? Luna moths.

Looking back, I can see how these fluttering, green giants could scare the bejeepers out of a bunch of city girls. However, I was more fascinated than frightened by these enormous moths; still am.

I went a couple decades without seeing them again until one June day a few years ago. A friend came into work at the resort on Hecla Island and announced that they had a giant green moth on their door screen. Needless to say, I was over there with the camera in short order. The image above was the result.

There’s just something compelling about these ghostly green insects that float, like the moonbeams their named for, through the early summer nights.  With a wingspan of about 4 inches, they’re one of the largest moths in Canada and arguably one of the most beautiful; but few people get the chance to see them. They’re nocturnal and only exist in their adult form for about a week, so to catch a glimpse of these beauties, timing is truly everything.

They actually have a lot in common with a much more abundant and much less revered insect that emerges a few weeks later here in the north woods, namely the fishfly. Like its very distant cousin, adult luna moths have one purpose: to mate and deposit eggs to ensure the next generation. Like fishflies, these Saturnid moths have no mouths and do not feed. Their large, fuzzy bodies and consequently larger energy reserves from their larval stage allow them to live longer than the fragile fishfly.

In the dark labyrinth of the nighttime forest, finding a suitable mate is hard work, so male lunas can travel kilometres, tasting the air with their antennae for the pheromones drifting from a ‘wick’ extending from the abdomen of a waiting female.  Because they’re needed for this function, the antennae of male luna moths are much larger and fluffier than those of females, making the sexes fairly easy to tell apart. The moth pictured above is a female. Once the sexes find each other, they lock together in copulation for up to 20 hours before she sets off to lay her eggs. A female can produce up to 300 eggs, scattering them around the forest, a half dozen or so at a time, on the underside of birch leaves to incubate for almost two weeks.

The larvae are just as impressive as the adults, a bright, almost fluorescent green caterpillar that you can find trundling along the trunks and branches of its host plant, munching away on the leaves and growing up to 4 inches long by the time it sheds its exoskeleton for the fifth time (a process known as ecdysis).

Up here in Manitoba, where the summers are not long enough to allow for two generations, lunas overwinter as pupae in their cocoons. It isn’t until the following June that they will emerge from this stasis, all crumpled and fragile. Slowly, over at least half an hour, the new moth will pump hemolymph (insect blood) into their wings, ‘blowing them up’ until they harden into their characteristic green sails. It’s an event you can witness first-hand if you’re lucky enough to find a caterpillar before it pupates and keep it at home over winter. I’m actually planning to try and do just that later this summer so that I won’t miss the emergence of one of my favourite denizens of the dark.

It’s a Hard-Knock Life

Juvenile Northern Saw-whet OwlsThere isn’t much else in the world that’s cuter than a baby Northern Saw-whet Owl. I should know; I handled dozens of them over the course of my doctorate research. Between their huge, blue, soulful eyes and the round, fluffy, ewok-like body, they’re guaranteed to evoke an ‘aww’ out of even the hardest-boiled egg of a person.

Still, most people will never have the opportunity to see one, at least not in their juvenile plumage. They’re notoriously hard to find.  Northern Saw-whet Owls nest in old tree cavities, moving into empty woodpecker holes and other crevasses in rotted out trunks. To study them more closely, researchers put up nest boxes in the hopes of coaxing them into more accessible real estate. It’s a lot easier to climb a ten-foot ladder up to a nest box than to have to figure out a way to get 25 feet up into a poplar or worse, a hydro pole.

Even once they’re out of the nest, they’re difficult to spot. Being not much bigger than a coffee mug full-grown, these little owls rely on camouflage to stay safe in the forests and woodlots where they make their home.  Their first line of defence when threatened is to go stock still against a tree trunk or in a mess of branches. It’s a very effective manoeuvre.  Adult saw-whets have stripes of brown and white on their breast feathers and spots on their heads that break-up their profile, helping them melt into the shadows. I can’t tell you how many times I’ve tracked a radio-tagged bird to their daytime roost and still couldn’t spot the little guy among the leaves. The brilliant white V on the forehead of juvenile birds is to help parents find their mouths in the dark of a nest cavity. Still, in daylight, this natural beacon manages to blend into the dappled sunlight on the foliage.

Adult Male Northern Saw-whet Owl

Adult male Northern Saw-whet Owl blending into the background.

So, any time I get to spend with these little guys is a treat, one that I never take for granted. It’s always such a pleasure to get to observe their individual personalities up close.

Don’t let their size and adorable expressions fool you. These are tough little birds. They have to be. Life for a Northern Saw-whet Owl is hard from day one. Females lay their eggs two days apart, but start incubating before they’ve completed the clutch. As a result, you end up with a nest full of young where the oldest may have a ten day head start on life over the youngest. In years where the small mammal population is high, the provisioning males can make their nightly quota of about seven or more prey items a night, making it possible for all the young to make it out of the nest. However, in years where food is scarce, that age difference suddenly comes into sharp relief and it’s not uncommon to find only one or two of the oldest nestlings surviving out of a clutch of 4-6.

Even if they make it out of the nest, life doesn’t get much easier. After a month crammed into the nest hole with mom and all their siblings, you’d think these newly-fledged saw-whets would want to move on and take advantage of their new-found freedom as quickly as possible.  However, despite having fully-feathered wings by the time they leave the nest (unusual for owls), juveniles tend to hang around the homestead for another month or so. They spend their days tucked away in the shadows in nearby trees and their nights calling insistently for food deliveries from their already beleaguered father, their mother having taken off around the time the oldest hit 21 days for a much-needed break.  During this post-fleding period, young saw-whets practice flying and refine their hunting skills.

Eventually, it’s time for them to strike out on their own into the great unknown. It’s actually a great unknown for us researchers as well. Despite a number of long-term banding programs for the species all over North America, we still don’t have a very good handle on saw-whet owl movements outside of the breeding season.

So every year, my colleagues across the country and I will keep adding new nest boxes and checking the ones we have, spending as much time as we can peering into the lives of these adorable and enigmatic owls in the hopes that one day we might unravel a few more of their mysteries.

* If you would like to entice owls to your backyard, let me know, and I’ll send you the plans for building a nestbox.

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.

Flying with Dinosaurs

Canada goose and dinosaurSince the beginning of January, I’ve had the pleasure of teaching a second-year Chordate Zoology course at the University of Winnipeg. Having taken it at a different school as an undergrad and having taught the labs several years ago, the material isn’t exactly new. However, it’s been a wonderful way to rediscover the fascinating story that is the evolution of vertebrates.

First and foremost, it’s reminded me that we see dinosaurs just about everyday, flitting through the trees, soaring high overhead and gliding across a glassy pond. They’re all around us, bringing colour and music to our world.

Because of my grounding in zoology, the concept that birds are dinosaurs is not new to me, nor is it difficult to understand. However, I imagine for many people it’s a bit of a challenge to make the mental leap from a chickadee flitting among the leaves to a giant Tyrannosaurus rex thundering along a Cretaceous plain.  Still, whether you can see the resemblance or not, the genetic relationship is undeniable. A spectacularly rare discovery in 2007 of intact collagen protein in the fossil leg bone of a T-Rex allowed researchers to compare the amino acid chains within with a database of species we already have sequences for. It turned out that of all the possibilities, from mammals to reptiles, the sequence was most closely related to the collagen sequence of a chicken. This discovery probably would’ve left good ol’ Colonel Sanders with nightmares!

Even without the molecular connection, you can still see the family resemblance. Birds are descended from a lineage of dinosaurs known as Theropods, swift, bipedal predators, like Velociraptor, Deinonychus (pictured above) and the aforementioned T. Rex. While the ones most people are familiar with, thanks to Jurassic Park, are the large, ferocious creatures, most of this lineage were rather small, adapted for running and pouncing on their prey. These adaptations for speed and agility can still be seen in the skeletons of the last remaining dinosaurs, the birds.

They walked on two legs, their limbs swinging back and forth on the fulcrum of a pelvis that looked like part of a bicycle. Over time, that pelvis shifted, the individual bones fusing and getting stonger to withstand the strain brought by high speeds while maintaining its light weight. In fact, weight reduction was the order of the day in the evolution of birds from their theropod ancestors. Bones, overall, got smaller, lighter, hollowing out into tubes that were, and still are, reinforced by thin struts called trabeculae. The pectoral girdle got both smaller and in some ways, more rigid. Where the scapulae were freed up to allow the arms to swing out like flapping wings, the clavicles fused, forming the furcula (wishbone) and the sternum developed a deep keel, giving more space for what eventually became flight muscles to attach.

Still, the most striking feature these dinosaurs had in common with the ones we see today was feathers. That’s right, Creighton missed that little detail. Many theropods, Velociraptor included, had feathers. They started out as long, thin fibers that offered the minimum of insulation, gradually developing into the differentiated flight, covert and down feathers we know now. They appeared at least 160 million years ago, long before Archaeopterix (the first official bird) and even non-avian theropods like Velociraptor and Deinonychus. Paleontologists have found them in numerous species, including a small chicken-like theropod (the whole protein thing is making sense now) named Anchiornis. They’ve even managed to determine the colour of the feathers by examining the shape of the melanosomes (tiny pockets of pigment) preserved in the fossilized remains.

As more and more of these characteristics are teased from the fossil record, I can’t help but hope that one day my field guide to birds includes a section on the species that paved the genetic way for the spectacular diversity we see today.

Sounds of Silence

White-tailed deerWalking 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.