Have you heard of the woodcock? What about the timberdoodle? It’s the same bird. The same, strange-looking bird. Spring is a key time for the plump, stubby-necked avian. With its bizarre preportions—look at that long beak—it’s hard to imagine that the woodcock would be a strong flier. But it is. And beginning in March, males take to the skies to woo their future lady loves with astonishing courtship flights.
What does the woodcock sound like?
About 20 minutes after sundown in early spring, male woodcocks start to call to the ladies: peent, peent, peent. It’s nasal and buzzy, and audible from more than 200 metres away. A male will repeat the sound every few seconds for a couple of minutes, then launch into the air, spiralling through the sky 100 metres up. Then he abruptly hurtles back to earth, flying in a zigzag pattern. He repeats this aerial dance about a dozen times, and does the same thing again at dawn, for two months. That’s dedication.
What do woodcocks eat?
The woodcock isn’t nearly as fancy-footed on the ground, but it does move in an unusual way. While foraging—for beetle grubs, maggots, and millipedes—the robin-sized bird camouflages with its surroundings thanks to its buff, brown, and black feathers. It bobs back and forth, shifting its weight from foot to foot as it uses its upper bill to probe the leaf litter. The upper bill has a flexible, serrated tip that’s full of blood vessels. The woodcock uses it to detect the vibrations of critters in the soil—mostly earthworms, a staple food. Experts think the bird’s back-and-forth movement is intentional, to encourage worms to burrow deeper, and therefore, make noise that the woodcock can “hear”. Sneaky trick!
Flowers are one of the most striking examples of diversity in nature, displaying myriad combinations of colours, patterns, shapes and scents. They range from colourful tulips and daisies, to fragrant frangipani and giant, putrid-smelling corpse flowers. The variety and diversity is astounding—consider the duck-shaped orchid.
But as much as we can appreciate the beauty and diversity of flowers, it is quite literally not meant for our eyes.
The purpose of flowers is to attract pollinators, and it is to their senses that flowers cater. A clear example of this are ultraviolet (UV) patterns. Many flowers accumulate UV pigments in their petals, forming patterns that are invisible to us, but that most pollinators can see.
The disconnect between what we see and what pollinators see is particularly striking in sunflowers. Despite their iconic status in popular culture (as testified by the arguably dubious honour of being one of the only five flower species with a dedicated emoji), they hardly seem the best example of flower diversity.
However, when looked at in the UV spectrum (that is, beyond the type of light that our eyes can see), things are quite different. Sunflowers accumulate UV-absorbing pigments at the base of the ligules. Across the whole inflorescence, this results in a UV bullseye pattern.
In a recent study, we compared almost 2,000 wild sunflowers. We found that the size of these UV bullseyes varies extensively, both between and within species.
The sunflower species with the most extreme diversity in the size of UV bullseyes is Helianthus annuus, the common sunflower. H. annuus is the closest wild relative to cultivated sunflower, and is the most broadly distributed of wild sunflowers, growing almost everywhere between southern Canada and northern Mexico. While some populations of H. annuus have very small UV bullseyes, in others, the ultraviolet-absorbing region covers the whole inflorescence.
When we compared sunflowers with different UV bullseyes, we found that pollinators were able to discriminate between them and preferred plants with intermediate-sized UV bullseyes.
Sunflowers with different UV bullseye patterns as we see them (top) and as a bee might see them (bottom). (Marco Todesco), Author provided
Still, this doesn’t explain all the diversity in UV patterns that we observed in different populations of wild sunflowers: if intermediate UV bullseyes attract more pollinators (which is clearly anadvantage), why do plants with small or large UV bullseyes exist?
Other factors
While pollinator attraction is clearly the main function of floral traits, there is increasing evidence that non-pollinator factors like temperature or herbivores can affect the evolution of characteristics like flower colour and shape.
We found a first clue that this could also be the case for UV patterns in sunflowers when we looked at how their variation is regulated at the genetic level. A single gene, HaMYB111, is responsible for most of the diversity in UV patterns that we see in H. annuus. This gene controls the production of a family of chemicals called flavonol glycosides, which we found in high concentrations in the UV-absorbing part of ligules. Flavonol glycosides are not only UV-absorbing pigments, but play also an important role in helping plants cope with different environmental stresses.
A second clue came from the discovery that the same gene is responsible for UV pigmentation in the petals of the thale cress, Arabidopsis thaliana. Thale cress is the most commonly used model system in plant genetics and molecular biology. These plants are able to pollinate themselves, and therefore generally do without pollinators.
Thale cress can pollinate itself without the help of pollinators. (Shutterstock)
Since they don’t need to attract pollinators, they have small, unassuming white flowers. Still, their petals are full of UV-absorbing flavonols. This suggests that there are reasons not related to pollination for these pigments to be present in the flowers of the thale cress.
Finally, we noticed that sunflower populations from drier climates had consistently larger UV bullseyes. One of the known functions of flavonol glycosides is to regulate transpiration. Indeed, we found that ligules with large UV patterns (which contain large amounts of flavonol glycosides) lost water at a much slower rate than ligules with small UV patterns.
This suggests that, at least in sunflowers, patterns of floral UV pigmentation have two functions: improving the attractiveness of flowers to pollinators, and helping sunflowers survive in drier environments by preserving water.
Thrifty evolution
So what does this teach us? For one, that evolution is thrifty, and if possible will use the same trait to achieve more than one adaptive goal. It also offers a potential approach for improving cultivated sunflower, by simultaneously boosting pollination rates and making plants more resilient to drought.
Finally, our work, and other studies looking at plant diversity, can help in predicting how and to which extent plants will be able to cope with climate change, which is already altering the environments they are adapted to.
The greater yellowlegs has—wait for it—yellow legs. Good call, whoever gave this shorebird its common name. In March, the migratory bird begins to come home from winter U.S. digs in brackish wetlands, mudflats, flooded fields, and, ugh, sewage ponds, headed to Canada’s boreal wetlands and damp meadows. Greater yellowlegs parents seem to prefer shallow water and shrubby ponds where they can safely raise their kids. Who wouldn’t? During breeding season, the birds will sometimes fly up to and then perch on trees to watch for predators.
The greater yellowlegs vs the lesser yellowlegs
The greater yellowlegs walks with a high-stepping gait, its limbs flashing. Its cousin species, the lesser yellowlegs looks (no surprise) almost identical. But the greater bird is literally greater—that is, larger—with a longer, thicker bill. Side-by-side, most folks could see the difference, but when each bird is solo, it can be hard for anyone but an experienced birder to ID each yellowlegs.
What does this bird sound like?
The greater yellowlegs’ screechy alarm call is one reason why birdwatchers don’t love this guy. It tends to scare away other shorebirds, so its nicknames are “tattler” and “yelper.” The most common call is a chirpy, ringing cry: tew tew tew. (It sounds, at least to some people, that the bird is saying its name: “yel-low-legs”). If you want to hear the bird in real life, be prepared to spend some time in boggy areas. When it’s dry, head to muddy reservoirs or lakes; when it’s wet, you can spot them in flooded fields. Adult birds also tend to wade into deeper water compared to other sandpipers—one reason that birders call the greater yellowlegs a “marshpiper.”
Cottages are seen as a ‘home away from home’, a place to relax, recharge, and rejuvenate. But they can also provide a home for wildlife. The chimney swift, a small grey cigar-shaped bird that preys on mosquitoes and other flying insects, has adapted to roost and nest in human-made structures—preferring, as the name suggests, chimneys. However, chimney swifts in Canada are in major trouble; over 90% of the population has declined since 1970.
To help conserve the species, Birds Canada, with financial support from Environment and Climate Change Canada, has launched the Chimney Swift Chimney Restoration Fund. Owners of structures in need of repair and used by chimney swifts for nesting and roosting can apply for financial support from the fund. The fund may provide up to 50% of the total cost of the restoration project, while ensuring that the repairs continue to allow chimney swifts to use the structure for nesting and roosting.
Chimney swifts tend to occupy buildings that were built before 1960, says Véronique Connolly, coordinator for the Chimney Swift Fund. As aging chimneys fall apart or are capped or demolished, the chimney swifts lose out on valuable habitat.
“Often chimney owners don’t have the financial resources to repair a chimney. Sometimes it’s easier just to demolish it,” says Connolly.
Chimney swifts seek out chimneys built with rough materials like brick, stone, or concrete. “Chimney swifts can’t perch like birds that you would see on telephone wires,” says Natasha Barlow, a projects biologist for Birds Canada. Their back toes can swivel forward though, helping the birds cling to rough surfaces, she says.
Those rough building materials also provide a nice attachment area for swifts to construct their nests. Chimney swifts use saliva to glue small twigs together and then adhere the nests onto interior chimney walls, says Andrew Coughlan, the Quebec director for Birds Canada.
Coughlan maintains that chimney swifts make good tenants. “They’re not particularly noisy, and they don’t make huge nests,” he says. ”Nests are very small—about four inches wide—so it’s not going to block the chimney or cause a fire hazard.”
Sharing your cottage or home with chimney swifts doesn’t mean ceding your chimney entirely to the birds, adds Barlow. Chimney swifts migrate south for the fall and winter, so homeowners are perfectly safe to use their fireplaces and chimneys as intended while the birds are away.
The application deadline for the fund is April 21, 2022. Applicants can visit the Chimney Swift Chimney Restoration Fund’s website for the full eligibility criteria and application process.
Unless you’re very familiar with plains-dwelling animals, you’d probably never peg the Richardson’s ground squirrel as a relative of the red squirrel or the grey squirrel. These mammals look much more like gophers or small prairie dogs. And they behave more like both: “ground squirrel” is an incredibly apt common name given how much of their lives these critters spend underground! (It’s a lot—see below.)
Ground squirrels vs. tree squirrels
The species was named after the Scottish naturalist Sir John Richardson. Looks-wise, they have larger bodies but much smaller tails than their tree squirrel relatives. (Tree squirrels need bushy tails to help with balance.) A ground squirrel’s skinny tail is almost constantly twitching, like a tiny whip—it’s one reason why they’re nicknamed “flickertails.” Their ears, meanwhile, are so flat that they appear mashed into either side of the head.
When do they hibernate?
The Richardson’s ground squirrel spends up to eight months hibernating. Adults emerge from their dens—in Canada, dug into open meadows and plains in the prairie provinces—between February and March. They return underground by mid-June at the latest. Juvenile squirrels spend a little less time in hibernation—between five and seven months. But even when the squirrels are not hibernating, they’re still only aboveground for eight to 10 hours of the day. An individual Richardson’s ground squirrel spends a mere 15 per cent of its existence on the surface. (Imagine living 85 per cent of your life in the basement.)
Ground squirrel dens provide digs for other prairie dwellers
Richardson’s ground squirrel burrows play an important role in the lives of other denning creatures. Mice, voles, burrowing owls, badgers—they enlarge the holes to suit their bigger bodies—plus salamanders and invertebrates repurpose empty dens. Even bumblebees nest in ground squirrel homes.
When do ground squirrels reproduce?
Squirrels mate soon after they emerge from hibernation in early spring. Females all give birth around the same time, so the population explodes all at once. But it can crash just as quickly: mortality is especially high with this species, thanks to prairie predators such as hawks, falcons, eagles, weasels, and rattlesnakes. About 50 to 70 per cent of babies don’t live long enough to reproduce (at about a year old). Despite this, it’s common to spot both adults and babies in Manitoba, Saskatchewan, and Alberta—at least, it’s more common to spot them than it is to spot other grassland mammals. They’re bold, and will happily approach people, looking for handouts. Cheeky!
I have studied coyotes and other wild canids for over 30 years. Co-existence with coyotes is possible. My understanding comes from many places: being a care-giver to orphaned coyote pups, studying the development of coyote play and communication, helping trap and radio-collar them, supervising multiple theses and, most recently, monitoring a multi-generational coyote family for years. I interact with coyotes at very close range, and sparingly use aversive conditioning, which involves using my voice, body, and a held object to establish boundaries.
Distorted risks
I am often asked how citizens can protect themselves against “aggressive coyotes.” In my research, I found that coyotes rarely exhibit aggression, but human fear of coyotes is pervasive and overrides scientific evidence. While sometimes unintended, the use of risk narratives (including misplaced words like bold, aggressive) by scientists or media has the demonstrated effect of tapping into existing fear—this is referred to as the “social amplification of risk.”
People then normalize the idea that coyotes are likely to attack, rather than the more apt narrative: Coyotes are simply trying to survive, preferring to avoid people. When coyotes react, it is to protect themselves, their mates or pups from an actual or perceived threat, like dogs chasing them or coming into a den area, or a person poking at the den with a stick. In the reports that I have reviewed where dogs were attacked, over 90 per cent involved dogs off-leash and at-large.
Coyote reactions stem from context and experience, they are varied and rarely about aggression. Habituation in cities may have led to delayed or less dramatic responses in coyotes, as compared to non-urban coyotes that often desperately flee from humans.
Living in the city
Conflict with coyotes is preventable, but when it occurs, it does so in the context of several human-centred factors. Habituation of coyotes is often the first identified culprit. This means that the coyotes become accustomed to human activities, learn to “tune them out” and direct attention to those things that are more important, like finding food.
In wildlife observational research, scientists often strive for animal habituation so the observer may be in plain sight, yet “invisible,” allowing animals to do what they do. In the absence of immediate threats, coyotes learn to sometimes disregard humans.
Habituation may lead to proximity issues, which can cause conflict if it is coupled with food conditioning—the intentional or unintentional feeding of coyotes. This arises when people fail to keep yards free of food attractants like dog food, bird seed, fallen fruit, or compost. A coyote learns to depend on that food source, which can can increase the risk of the coyote guarding food against people and pets.
What is most catastrophic to co-existence is when people decide to deliberately feed coyotes. That often is a death sentence for the coyote because it can eventually demand food. Coyote demand behaviour may include a coyote latching on to a person’s clothing or limbs in an attempt to get food, and can be mistakenly classified as aggression or attack. Once a coyote has bitten a person, the chances of rehabilitation are low relative to the risk of escalation, and a coyote exhibiting this behaviour would likely be killed.
Several studies about coyote diet in Calgary, conducted in my lab, showed less than two per cent of samples contained pet remains. Coyotes are not fully to blame: the city has a bylaw prohibiting free-ranging pets, which many people disregard, subjecting their pets to possible death by owl, eagle, bobcat, domestic dog, coyotes and vehicles. Coyotes often just scavenge, earning them the label “nature’s clean up crew.”
Dog encounters
Coyote parents are very defensive of their pups, who are born around early April. (Shutterstock)
Coyote pups are usually born around early April, known as denning season, and coyotes shift into pup-guarding mode. As a result, there can be a spike in conflict between dogs and coyotes, almost exclusively due to a perceived intrusion by a domestic dog.
Coyotes may first warn by standing and staring, this will increase to vocalization, a bluff charge, then an attack on the dog if the owner does not withdraw immediately.
Coyotes in non-urban situations might prefer certain den characteristics (for example, south-facing slopes), but in fragmented green spaces that dot cities, coyotes may be forced to be resourceful—and the more disturbed they are by people or dogs, the more prone the coyotes are to move pups somewhere perceived to be safer.
Last year at one study site, I observed hundreds of people a week, many with dogs, walked right past a father or mother coyote with four pups less than 30 metres away. The parent coyotes were measured, careful and avoided conflict routinely. Over the course of thousands of possible interactions that summer, there were six reports of “aggressive” or “bold” coyote interactions. In these rare cases, a parent coyote either escorted, bluff charged or vocalized to repel dogs that were allowed to wander in closed areas—there were no attacks or injuries.
On the University of Calgary campus, we have a peaceful wildlife co-existence program, based on monitoring and investigation, education, enforcement, and mitigation. With the help of supportive staff and faculty, responsive deployment of signage or closures, removal of attractants and the measured use of humane aversive conditioning, our program ensures coyotes and surrounding communities continue to use the campus safely, promoting biodiversity and sustainability in the urban ecosystem.
I have studied coyotes and other wild canids for over 30 years. Co-existence with coyotes is possible. My understanding comes from many places: being a care-giver to orphaned coyote pups, studying the development of coyote play and communication, helping trap and radio-collar them, supervising multiple theses and, most recently, monitoring a multi-generational coyote family for years. I interact with coyotes at very close range, and sparingly use aversive conditioning, which involves using my voice, body, and a held object to establish boundaries.
Distorted risks
I am often asked how citizens can protect themselves against “aggressive coyotes.” In my research, I found that coyotes rarely exhibit aggression, but human fear of coyotes is pervasive and overrides scientific evidence. While sometimes unintended, the use of risk narratives (including misplaced words like bold, aggressive) by scientists or media has the demonstrated effect of tapping into existing fear—this is referred to as the “social amplification of risk.”
People then normalize the idea that coyotes are likely to attack, rather than the more apt narrative: Coyotes are simply trying to survive, preferring to avoid people. When coyotes react, it is to protect themselves, their mates or pups from an actual or perceived threat, like dogs chasing them or coming into a den area, or a person poking at the den with a stick. In the reports that I have reviewed where dogs were attacked, over 90 per cent involved dogs off-leash and at-large.
Coyote reactions stem from context and experience, they are varied and rarely about aggression. Habituation in cities may have led to delayed or less dramatic responses in coyotes, as compared to non-urban coyotes that often desperately flee from humans.
Living in the city
Conflict with coyotes is preventable, but when it occurs, it does so in the context of several human-centred factors. Habituation of coyotes is often the first identified culprit. This means that the coyotes become accustomed to human activities, learn to “tune them out” and direct attention to those things that are more important, like finding food.
In wildlife observational research, scientists often strive for animal habituation so the observer may be in plain sight, yet “invisible,” allowing animals to do what they do. In the absence of immediate threats, coyotes learn to sometimes disregard humans.
Habituation may lead to proximity issues, which can cause conflict if it is coupled with food conditioning—the intentional or unintentional feeding of coyotes. This arises when people fail to keep yards free of food attractants like dog food, bird seed, fallen fruit, or compost. A coyote learns to depend on that food source, which can can increase the risk of the coyote guarding food against people and pets.
What is most catastrophic to co-existence is when people decide to deliberately feed coyotes. That often is a death sentence for the coyote because it can eventually demand food. Coyote demand behaviour may include a coyote latching on to a person’s clothing or limbs in an attempt to get food, and can be mistakenly classified as aggression or attack. Once a coyote has bitten a person, the chances of rehabilitation are low relative to the risk of escalation, and a coyote exhibiting this behaviour would likely be killed.
Several studies about coyote diet in Calgary, conducted in my lab, showed less than two per cent of samples contained pet remains. Coyotes are not fully to blame: the city has a bylaw prohibiting free-ranging pets, which many people disregard, subjecting their pets to possible death by owl, eagle, bobcat, domestic dog, coyotes and vehicles. Coyotes often just scavenge, earning them the label “nature’s clean up crew.”
Dog encounters
Coyote parents are very defensive of their pups, who are born around early April. (Shutterstock)
Coyote pups are usually born around early April, known as denning season, and coyotes shift into pup-guarding mode. As a result, there can be a spike in conflict between dogs and coyotes, almost exclusively due to a perceived intrusion by a domestic dog.
Coyotes may first warn by standing and staring, this will increase to vocalization, a bluff charge, then an attack on the dog if the owner does not withdraw immediately.
Coyotes in non-urban situations might prefer certain den characteristics (for example, south-facing slopes), but in fragmented green spaces that dot cities, coyotes may be forced to be resourceful—and the more disturbed they are by people or dogs, the more prone the coyotes are to move pups somewhere perceived to be safer.
Last year at one study site, I observed hundreds of people a week, many with dogs, walked right past a father or mother coyote with four pups less than 30 metres away. The parent coyotes were measured, careful and avoided conflict routinely. Over the course of thousands of possible interactions that summer, there were six reports of “aggressive” or “bold” coyote interactions. In these rare cases, a parent coyote either escorted, bluff charged or vocalized to repel dogs that were allowed to wander in closed areas—there were no attacks or injuries.
On the University of Calgary campus, we have a peaceful wildlife co-existence program, based on monitoring and investigation, education, enforcement, and mitigation. With the help of supportive staff and faculty, responsive deployment of signage or closures, removal of attractants and the measured use of humane aversive conditioning, our program ensures coyotes and surrounding communities continue to use the campus safely, promoting biodiversity and sustainability in the urban ecosystem.
Look, it’s a black-capped chickadee! No, wait, it’s a boreal chickadee. Every Canadian can recognize the former, and its calls. But the lesser-known boreal chickadee has the same tiny body, big head, and round belly. (Adorbs.) Look carefully, though, and you’ll note the differences between the two species. The boreal chickadee has a brown cap, and darker, cinnamon-coloured sides. (Why isn’t it called the brown-capped chickadee? Good question.)
Where does the boreal chickadee live?
In North America, this songbird sticks almost exclusively to spruce and fir forests in Canada, and a few neighbouring states, such as Alaska. You can find these chickadees in almost every province, and, like black-caps, they don’t migrate (though they’ll move slightly south in the winter if there are food shortages). They prefer to feed off older trees. They’ll cling to tree cones, and poke around with their beaks to get at seeds or bugs. Their short bills are also tough enough to loosen tree bark and uncover insect eggs and larvae.
What does the boreal chickadee sound like?
The species produces a call that’s similar to its black-capped cousin’s, but it’s a little rougher and harsher, less sweet and melodic: tschick-a-dee-dee. Like other birds, boreals have all kinds of vocalizations, for alarm, warning, courtship, and aggression—everything from a low gargle to a twitter to a series of short chirps and squeals. Still, it’s a lot less chatty than the black-capped chickadee—one reason why some birders consider the boreal reclusive. And unlike our other chickadee species, the boreal chickadee doesn’t vocalize to announce its breeding territory. (For such a wee bird this can be a large chunk of real estate: up to 13 acres.) Instead, to scare off intruders, males will use a chin-up motion, or a “ruffle display”: they puff up their feathers and wings. Oh, stop frontin’, chickadee. Just kidding. We know that you’re tough.
Are they endangered?
Because boreal chickadees have a more remote and northern range than many other bird species, it’s hard for experts to monitor their numbers. Still, one survey estimated that population increased by 38 per cent between 1970 and 2017, and according to the North American Breeding Bird Survey, their numbers appear stable. So even though a lot of avian species are struggling, the future looks bright for this bird.
Zoom in and explore the northern boreal forests of western Canada on Google Earth and you’ll see long straight lines making their way through the forest. These lines are cleared trails through the forest to extract resources, creating roads for forestry and seismic lines searching for underground oil and gas deposits.
Now picture yourself faced with the task of moving across this landscape: Will you push your way through dense trees and underbrush, or will you choose to walk on the trails?
Like humans, wolves often choose the path of least resistance, moving faster and farther on human-created trails through the forest. Increased wolf movement is believed to play an important role in the decline of the threatened boreal woodland caribou—an iconic species in Canada (just look at the quarter in your pocket).
We tracked 142 wolves using GPS collars across British Columbia, Alberta and Saskatchewan—spanning over 500,000 square kilometres. The tracked wolves spanned areas with low to high prey density (measured using a metric of habitat productivity, or how much vegetation there is for species like moose), and had varying access to human-created trails.
Wolves living in areas with high densities of human-created trails took up an area roughly 20 times smaller than wolves without trails, but only when they lived in areas with low habitat productivity. Comparatively, trails didn’t change the area needed for wolves when they lived in areas with high habitat productivity.
Think about picking berries. If the berries are hard to find, you have to go looking far and wide to get enough to fill up your basket. But if something makes it easier for you to find the berries, then you don’t have to look around as much. You can just grab all the ones that you see close to you. The advantage of being able to easily find berries would be less important if there are a lot because you can skip over a few without noticing. But it becomes more important when there are few to begin with, and every last berry counts.
This is exactly what we are seeing with wolves: Instead of choosing to travel far and wide, wolves with access to lots of trails stay close to home and get by with what they have.
The space animals use to carry out their lives is called a home range, or if defended from conspecifics like in the case of wolves, a territory. If animals have smaller home ranges, that means more animals can crowd into a given space, increasing the density of that species. It is well documented that animals need less space when there is an abundance of food around—and now we know that easier access to that food can also decrease home range size. We found that increasing a wolf’s access to their prey, through things like cleared trails through the forest, can decrease their home range size, likely increasing the regional density of wolves.
Habitat restoration
But why do we care about how big wolf home ranges are? One of the biggest conservation challenges in Canada is that of woodland caribou. Caribou live across large areas, overlapping places where the energy and forestry sectors are actively extracting natural resources like oil, gas and timber.
A remote camera capture of caribou in the boreal forest. Changes in wolf-hunting patterns are threatening the already endangered caribou. (Melanie Dickie/Caribou Monitoring Unit), Author provided
Habitat restoration is imminently needed, but is expensive and time consuming. Prioritizing habitat restoration in areas where it will be most beneficial to caribou as soon as possible is necessary for effective caribou management.
Habitat restoration has two main goals: to reduce wolf hunting efficiency by limiting their use of trails and slow their movement when on them and to return the forest to caribou habitat. But now we have reason to believe that slowing wolves down can also reduce wolf density on the landscape — forcing individual wolves to take up more space and push others out—especially in low-productivity peatlands, where the effect on home ranges is stronger.
Effective habitat restoration is going to be important for moving away from other management actions like wolf management in the long term. But, we have a lot of work ahead of us. There are hundreds of thousands of kilometres of these cleared trails that need to be restored. Our study points us towards prioritizing low-productivity areas to see the biggest effects sooner.
Zoom in and explore the northern boreal forests of western Canada on Google Earth and you’ll see long straight lines making their way through the forest. These lines are cleared trails through the forest to extract resources, creating roads for forestry and seismic lines searching for underground oil and gas deposits.
Now picture yourself faced with the task of moving across this landscape: Will you push your way through dense trees and underbrush, or will you choose to walk on the trails?
Like humans, wolves often choose the path of least resistance, moving faster and farther on human-created trails through the forest. Increased wolf movement is believed to play an important role in the decline of the threatened boreal woodland caribou—an iconic species in Canada (just look at the quarter in your pocket).
We tracked 142 wolves using GPS collars across British Columbia, Alberta and Saskatchewan—spanning over 500,000 square kilometres. The tracked wolves spanned areas with low to high prey density (measured using a metric of habitat productivity, or how much vegetation there is for species like moose), and had varying access to human-created trails.
Wolves living in areas with high densities of human-created trails took up an area roughly 20 times smaller than wolves without trails, but only when they lived in areas with low habitat productivity. Comparatively, trails didn’t change the area needed for wolves when they lived in areas with high habitat productivity.
Think about picking berries. If the berries are hard to find, you have to go looking far and wide to get enough to fill up your basket. But if something makes it easier for you to find the berries, then you don’t have to look around as much. You can just grab all the ones that you see close to you. The advantage of being able to easily find berries would be less important if there are a lot because you can skip over a few without noticing. But it becomes more important when there are few to begin with, and every last berry counts.
This is exactly what we are seeing with wolves: Instead of choosing to travel far and wide, wolves with access to lots of trails stay close to home and get by with what they have.
The space animals use to carry out their lives is called a home range, or if defended from conspecifics like in the case of wolves, a territory. If animals have smaller home ranges, that means more animals can crowd into a given space, increasing the density of that species. It is well documented that animals need less space when there is an abundance of food around—and now we know that easier access to that food can also decrease home range size. We found that increasing a wolf’s access to their prey, through things like cleared trails through the forest, can decrease their home range size, likely increasing the regional density of wolves.
Habitat restoration
But why do we care about how big wolf home ranges are? One of the biggest conservation challenges in Canada is that of woodland caribou. Caribou live across large areas, overlapping places where the energy and forestry sectors are actively extracting natural resources like oil, gas and timber.
A remote camera capture of caribou in the boreal forest. Changes in wolf-hunting patterns are threatening the already endangered caribou. (Melanie Dickie/Caribou Monitoring Unit), Author provided
Habitat restoration is imminently needed, but is expensive and time consuming. Prioritizing habitat restoration in areas where it will be most beneficial to caribou as soon as possible is necessary for effective caribou management.
Habitat restoration has two main goals: to reduce wolf hunting efficiency by limiting their use of trails and slow their movement when on them and to return the forest to caribou habitat. But now we have reason to believe that slowing wolves down can also reduce wolf density on the landscape — forcing individual wolves to take up more space and push others out—especially in low-productivity peatlands, where the effect on home ranges is stronger.
Effective habitat restoration is going to be important for moving away from other management actions like wolf management in the long term. But, we have a lot of work ahead of us. There are hundreds of thousands of kilometres of these cleared trails that need to be restored. Our study points us towards prioritizing low-productivity areas to see the biggest effects sooner.
