A global study using data from before and during COVID-19 lockdowns found wild animals have different responses to the presence of humans.
Carnivores like wolves (Canis lupus) and wolverines (Gulo gulo) tend to be less active when humans are around, preferring to avoid risky encounters. That’s good news for herbivores like deer and moose (Alces alces), which tend to become more active. So do urban animals, like racoons (Procyon lotor). But animals in rural areas are warier.
The study, published in Nature Ecology & Evolution, involved more than 220 researchers analyzing 163 mammal species and found on 5,000 camera traps around the world.
“COVID-19 mobility restrictions gave researchers a truly unique opportunity to study how animals responded when the number of people sharing their landscape changed drastically over a relatively short period,” said TWS member Cole Burton, an associate professor of forest resources management at the University of British Columbia and the study’s lead author.
“And contrary to the popular narratives that emerged around that time, we did not see an overall pattern of ‘wildlife running free’ while humans sheltered in place,” Burton said. “Rather, we saw great variation in activity patterns of people and wildlife, with the most striking trends being that animal responses depended on landscape conditions and their position in the food chain.”
The return of wolves to Yellowstone National Park, as well as the comeback of other predators, may not restore wetland ecosystems there as much as some scientists had hoped.
Gray wolves (Canis lupis) were extirpated in the park by the 1920s due to predator control efforts. But in the 1990s, wolves were reintroduced. At the same time, other predators, including grizzlies (Ursus arctos horribilis) and cougars (Felis concolor), began naturally returning to the area. Many have theorized that predation on elk (Cervus canadensis), which overgraze vegetation if left unchecked, has helped the ecosystem recover to its more historical state.
But research assessing the system for 20 years tells a different story. “There’s a lot of research analyzing ecosystems after predators are removed,” said David Cooper, a senior research scientist emeritus in the Warner College of Natural Resources at Colorado State University. But studies on reintroducing predators back into the ecosystem are harder to come by. “We weren’t really sure what to expect.”
Cooper and his colleague Tom Hobbs, an emeritus professor at Colorado State, were the senior authors of a study published in Ecological Monographs analyzing how the wolves’ and other predators’ returns affected riparian willows.
Beaver extirpation
In the past, elk fed heavily on willows, a riparian plant. In turn, beavers (Castor canadensis), no longer had food and material to build dams and raise the water table. Beavers were extirpated from this region of the park by the 1940s due to a lack of willows and from overharvesting them.
“These small streams had gone from a beaver-willow system, which was wet and dynamic, to an incised, dried-up floodplain that we call the elk grassland state,” Cooper said. He and his colleagues wanted to find out what bringing wolves back did to what he calls the “alternative elk-grassland state”—an ecosystem that had shifted entirely from its original state.
Cooper and Hobbs began working on this system in 2001. In the park’s northern range, they fenced off eight plots to prevent elk browsing. They constructed simulated beaver dams in some enclosed and non-enclosed plots to mimic how beavers would raise the water table. They chose where to create these based on a report from Cornell University, where scientists mapped out beaver colonies in Yellowstone in the 1920s. In addition, the team left some areas as controls. “This is a fully factorial experiment,” Cooper said. “We could test the effect of browsing versus water availability compared to the controls.”
After analyzing the willows in these plots, the team found that the shrubs had grown in the control plots, but not as much as you might expect. Even with all three predators in the ecosystem, the researchers found that browsing wasn’t really reduced all that much in the control plots. “We saw modest growth of willows in our 20-year experimental control plots,” he said.
Researchers tested how fencing and beaver dams may bring back willows in Yellowstone. Credit: David Cooper
What they did find was that in plots with simulated beaver dams and reduced browsing, willows did grow several meters tall. “But in sites where we just removed the browsing, they didn’t respond nearly as much as we would expect,” he said. That’s because these willows need water and didn’t get much without the simulated effects of beaver.
Overall, “the trophic cascade wasn’t really reinvigorated,” he said. “In other words, even with abundant predators, there was still extensive herbivory on our plants by elk and also bison.”
While elk populations have gone down, he added, bison (Bison bison) populations have gone way up. Wolves can’t really prey on bison because of their size, and bison also eat much more than elk do.
Other researchers have deduced similar findings about wolf reintroduction having less of an effect on aspen recovery in Yellowstone than initially thought.
But Cooper said this doesn’t mean wolves shouldn’t be introduced to their native ranges. “I believe that wolves are native animals,” he said. “They should be a part of our ecosystem, and they never should have been removed. The key is to maintain ecosystems intact, and then you never face these cascading issues or develop these alternative states that become stable and can’t be reversed.”
This is relevant now as wolves are being reintroduced to Colorado, although the situation there is a bit different than in Yellowstone. For example, elk hunting is allowed in Colorado, but it isn’t in Yellowstone. “I think the effects of wolves [in Colorado] will be even less than they were in Yellowstone,” he said. “We have a huge elk population [in Colorado] that’s well understood and carefully managed.”
On a research cruise focused on marine mammals and seabirds, Oregon State University scientists earned an unexpected bonus: the first-ever documented sighting of a hoary bat flying over the open ocean.
The bat was seen in the Humboldt Wind Energy Area, about 30 miles off the Northern California coast. The Humboldt area has been leased for potential offshore energy development, and the hoary bat (Lasiurus cinereus) is the species of bat most frequently found dead at wind power facilities on land.
OSU faculty research assistant Will Kennerley, the first to see the bat, and colleagues documented the sighting in a paper in the Journal of North American Bat Research.
Kennerley and Oregon State marine ecologist Leigh Torres were taking part in the MOSAIC Project, which studies seabirds and marine mammals around potential offshore wind energy areas.
“This demonstrates the value of having observers out on the water ready and able to document unexpected observations like this,” Kennerley said. “I think surprises like this are one of the most exciting parts of doing science.”
Researchers are planning to conduct a census of caribou on Baffin Island for the first time in a decade. A count in 2014 found caribou (Rangifer tarandus) on the island had declined from about 150,000 in the 1980s to about 4,600.
Researchers are hopeful the numbers are recovering after the Nunavut government imposed tighter hunting regulations.
“At this time, based on the annual composition surveys and hunter observations, there are positive and encouraging signs of possible recovery in some south Baffin areas,” said David Qavvik, Nunavut’s minister of environment.
I like to tell people I was raised by wolves. When I was a kid, I would flip over rocks to catch roly-polies, tear spring onions out of the ground to smell them, and hold dandelions to my face to see if I would be rich one day. I collected rocks that shimmered in the light, treasured empty snail shells, and watched hummingbirds nectar on pink mimosa trees that lined the house. I found magic in nature, and I believed the indigo rat snake (Drymarchon couperi) that lived in the bush was the keeper of my backyard, and you had to whisper secrets to be allowed to pass.
The solace I found in the outdoors was a stark contrast to the reality I faced indoors, which was a backdrop of abuse, turbulence and neglect. At 18 years old, I left home with a single box and my sweater that I used as a pillow. I chose my first apartment because it backed into the woods, so I could watch birds before work and fireflies shimmering at night after work.
Geest leads a July butterfly count at Lexington Wildlife Management Area in Oklahoma. She’s accompanied by Stephany Hernandez (left) and Kelly Dillow (right). Image Courtesy of Emily Geest.
I wasn’t the greatest student. I struggled with balancing a full course load, working full time, and managing my mental health throughout my undergraduate degree. I squeaked by with C’s in some courses and repeated the courses I failed. I would meet people who were open about their traumas, but I felt like I was failing because I couldn’t talk about mine. It felt as if I had a hand around my throat, stopping me from speaking. On the worst days, I would go down to the lake to name ducklings and watch blue-tailed skinks basking in the sun.
Thankfully, I had mentors who believed in me more than I believed in myself, and with their help, I made it to graduate school. During my PhD, everything I had been running from finally caught up to me, and I ended up in intensive weekly therapy. In the morning, I was counting butterflies and recording flowers. By the afternoon, I was learning about complex childhood trauma, a type of therapy called EMDR, and coping mechanisms in the afternoons. I learned what an ACE score of 9/10 meant—a type of measure of abuse, neglect and adverse childhood experiences—and how few people with my background made it to where I was. It felt like working on two dissertations at the same time: one on butterflies and the other on myself. I even had two graduations at the end: one after my defense and the other from my therapist’s office.
A headshot of Geest at the Oklahoma City Zoo and Botanical Gardens. Credit: Oklahoma City Zoo and Botanical Garden.
I still find magic in nature. I study butterflies and how they move and exist in a fractured world. I find the first robin of spring an enchanting moment, and I share with everyone the first migrating monarch I spot in the fall. It was the power of nature that helped me survive the darkest of days and inspired me to become a wildlife professional. I couldn’t share my story when I was younger, but I hope by doing so now that others who find themselves struggling realize that they aren’t alone, traumas can be overcome, and the future is beautiful and bright.
Wildlife Vocalizations is a collection of short personal perspectives from people in the field of wildlife sciences. Learn more aboutWildlife Vocalizations, and read other contributions.
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Boreal caribou in the Northwest Territories have led unimpeded lives for much of their existence. But roads—whether seasonal, temporary winter roads or more permanent gravel or paved highways—have crept into parts of the Canadian territory that were previously vehicle-free.
One such road, the Tłı̨chǫ All-Season Road (ASR), was built to replace the winter-only road connecting Highway 3, which runs from between Yellowknife and southern Canada, and the town of Whatì.
A winter seasonal road was replaced by the Tłı̨chǫ All-Season Road. Credit: GNWT-ECC
The earlier winter road, used to allow supplies into the town, traveled straight across frozen ground or stretches of ice on river crossings. From 2019 to December 2021, the Tłı̨chǫ ASR was constructed using gravel, generally following the route of the winter road.
Nilanjan Chatterjee, a postdoctoral fellow at the University of Minnesota (UM), and his colleagues John Fieberg from UM and Allicia Kelly, a biologist from the Government of the Northwest Territories, were investigating how this particular road construction might change the movements of foraging caribou northwest of the capital, Yellowknife.
Nilanjan Chatterjee presents his work on caribou and roads at The Wildlife Society’s 2023 Annual Conference in Louisville, Kentucky. Credit: Joshua Learn
As detailed in a presentation at The Wildlife Society’s 2023 Annual Conference in Louisville, Kentucky, Chatterjee and his colleagues examined GPS data from collared boreal caribou (Rangifer tarandus caribou). The data spanned before, during and after the construction periods of the Tłı̨chǫ road from 2017 to the present.
Boreal caribou in this area don’t travel in the massive herds that barren-ground caribou (R. t. groenlandicus) do farther north. Instead, they typically move in smaller groups of four to 20 individuals in the winter. In the early summer, they are more solitary.
The Tłı̨chǫ All-Season Road while under construction. Credit: D. Green/Kiewit
After analyzing data from 60 individuals, the researchers found that the caribou acted differently after the construction of the Tłı̨chǫ gravel road.
The researchers found the rate at which the caribou crossed the roads decreased over time as construction and road use began. The data also showed that the caribou began to approach the road and then turned back more during this time.
The Tłı̨chǫ All-Season Road after construction. Credit: GNWT-ECC
Quicker steps
The team also retrieved more fine-grained information on caribou movement. They found that during and after construction, when caribou were close to the Tłı̨chǫ road area, they seemed to move faster and turn less when they were near the road or crossing it. This likely indicated they were trying to get across quickly whenever they were near, the researchers said.
“Despite the relatively low amount of traffic on the new Tłı̨chǫ All-Season Road, we still detect an impact on caribou movements in proximity to the road,” said Kelly.
Boreal caribou in this area typically travel in groups of four to 20 individuals in the winter. Credit: J. Nagy/GNWT-ECC
In contrast, near busier Highway 3, the ungulates seemed more hesitant, moving more slowly.
“Near Highway 3, caribou took shorter, more tortuous steps when they were closer to the road and very rarely crossed the road,” Kelly said.
In the future, she said that it will be interesting to see if the caribou begin to change their behavior along the Tłı̨chǫ road if traffic there gets heavier like it is on Highway 3.
A truck travels down the relatively busier Highway 9. Credit: A. Kelly/GNWT-ECC
Secretive species can pose special conservation challenges simply because they are so cryptic, researchers known relatively little about them. One such species is the ringtail (Bassariscus astutus), a relative of the raccoon with cultural significance to many Indigenous peoples in North America.
A collaboration among scientists from Oregon State University, the Hoopa Valley Tribe, Penn State and Cal Poly Humboldt has shed light on the nocturnal carnivore.
Ringtails use the cavities of living trees or standing dead ones, called snags, to rest, avoid bad weather, hide from predators and make dens to raise their young. The research, conducted on the Hoopa Valley Reservation northeast of Eureka, California, found ringtails selected tree cavities in mature and older forests, as well as in younger forests with some older trees still present, rather than oak woodlands or other more open areas.
“And we found the presence of fishers, another charismatic, cat-like carnivore known to compete with ringtails for resources, did not influence where ringtails chose to rest,” said TWS member Sean Matthews, a wildlife ecologist with OSU’s Institute for Natural Resources and a co-author of the study published in in Northwest Science.
These findings differ from what is known ringtails in other portions of their range, Matthews said, and they offer guidance for forest managers seeking to conserve trees used by ringtails. “They’re definitely a species of conservation concern in California and Oregon,” he said.
Hoopa Tribal Forestry helped fund the study. The Western Section of The Wildlife Society was also among the organizations also supporting the research.
Chemical pollution may be messing with moths’ ability to stop and smell the roses at night, which may in turn affect pollination.
Nitrogen radicals form when increased levels of nitrogen oxides coming from human activity like fossil fuel emissions or car exhaust are released into the air.
“Because [nitrate radicals] are so reactive, it’s really important in degrading chemical compounds that are in the atmosphere,” said Joel Thornton, a professor of atmospheric sciences at the University of Washington (UW). “It’s produced all day long, and at night, but it’s actually broken down by sunlight. So it’s impact on the atmosphere is highest at nighttime.”
That’s the same time that nocturnal moths rely on smell rather than eyesight to seek flowers to pollinate. Researchers wondered if the nitrate radicals interfered with the chemical compounds that create the smell of the flowers that attract moths.
In previous research, Jeff Riffell, a professor of biology at the University of Washington, discovered compounds from car emissions were linked to moths’ difficulty finding flowers. He teamed up with Thornton to find out how nitrate radicals specifically change the scent compounds of flowers and how the pollinators’ behavior changes as a result. They published a study on their findings, led by PhD student at UW, Jeremy Chan, in Science.
The team chose to focus on the evening primrose, a flower that blooms at night in grassland areas from Arizona into Washington state, and the species that pollinate it. Pollinators included the white-lined sphinx (Hyles lineata) and the tobacco hawkmoth (Manduca sexta). The pollinators travel between patches of these flowers miles away from one another, requiring strong metabolic costs to find these flowers.
The team suspected nitrate radicals might be affecting the natural scents these flowers release. Their study included a few different components. The first step was to identify the chemical compounds in the flower’s scent blend. The researchers put a bag over the flowers for the scent to accumulate and trap the compounds. Back at the lab, they identified about 60 different components and chemically identified compounds for 22 of them.
The team then wanted to know which scents the moths were keying in on. They isolated each component of the scent and tested out which ones the moths’ antennae, which they smell with, were responding to. They found the moths preferred a type of scent chemical compound called monoterpene—the same compound used to make the scent in products like Pine Sol.
For the next step, the researchers wanted to see how the moths’ behavior would change when they were offered natural scent blends compared to scents that had been exposed to nitrate radicals. To do this, the team placed both blends of the compounds on fake flowers. They put the flowers at the end of a wind tunnel and released white-lined sphinx and tobacco hawkmoths at the other end to see which the insects preferred. “A gentle wind was going down this rectangular tube, carrying the scent blend from one end to the other,” Thornton said.
A tobacco hawkmoth visits an artificial paper flower emitting a pale evening primrose scent. Credit: Charles Hedgcock/University of Washington
They discovered that both moth species flew toward the natural scent mixture. But when it came to flowers treated with scents affected by nitrate radicals, white-lined sphinx couldn’t locate the flowers at all, and tobacco hawkmoths’ accuracy declined by 50%.
To see if it was the loss of monoterpenes that was the driver of moths having less accuracy, the team removed the monoterpenes from a natural scent blend and conducted the same experiment. “The moths’ behavior was changed to the same degree as when we added nitrate radicals,” Thornton said.
The researchers wondered if similar things might be happening in other parts of the world. Understanding the mechanism behind scents and nitrate radicals allowed the researchers to predict where else this may be important. Using a computer model that took into account the abundance of nitrogen oxides from different locations and weather patterns, they found that western North America, Europe, the Middle East, Central and South Asia and southern Africa may face similar challenges in plant-pollinator communication. “This global simulation map showed that each area has its own potential effect,” Riffell said, adding that daytime pollinators may also be subject to other kinds of chemical processes than nighttime pollinators.
“There’s a variety of stressors that are impacting native pollinators,” Riffell said—including climate change, habitat change and loss. In addition, he said, there are other kinds of atmospheric pollutants impacting daytime pollinators.
Luckily, the researchers said nitrate radicals have been decreasing over time in the U.S. “Strong trends from satellites have shown concentrations have halved since the mid-2000s,” Thornton said.
Northern elephant seals have made a remarkable comeback from the brink of extinction, but it hasn’t been without consequences. Researchers found that their reproductive and foraging success has been affected by the population bottleneck from the turn of the 20th century.
Hunted for the oil in their blubber in the 19th century, they were believed to be extinct in 1892. But about 20 survived, and today, their population has grown to over 200,000.
Their resurgence was considered a great success, but researchers recently found the population bottleneck compromised key genes associated with reproductive success and the seals’ ability to forage efficiently.
The research team analyzed nearly 270 northern elephant seals exploring their entire genetic make-up and comparing pre- and post-bottleneck northern elephant seals (Mirounga angustirostris). Their results showed an extreme direct loss of diversity due to the bottleneck event and found the overall fitness in the modern population had been impacted.
“So far, the species has recovered remarkably well, but these findings call into question how susceptible it might be to environmental stresses in the future,” Rus Hoelzel, professor at Durham University and the lead author of the study published in Nature Ecology & Evolution.
An imperiled wolf species survives poorly outside the boundaries of a provincial park in Ontario.
“The two most likely outcomes for eastern wolves outside of the park are death or hybridization,” said TWS member John Benson, an associate professor of wildlife biology at the University of Nebraska-Lincoln.
Eastern wolves (Canis lycaon) were once thought to range more widely across the Great Lakes regions of Canada and the United States, as well as into Quebec, New York state and New England. Ecologically, they are similar to the red wolf (C. rufus) population reintroduced to North Carolina—in fact, some even consider eastern and red wolves to be the same species, though this is debated, Benson said.
But as wolves were extirpated from many of these regions in the East, coyotes (C. latrans) began to move in from the West, colonizing areas in eastern North America left open by the absence of eastern wolves.
The main genetic holdout for eastern wolves is now Algonquin Provincial Park—a protected area in southeastern Ontario about the size of Yellowstone National Park in the U.S., though some are found in and around other protected areas in central Ontario and in pockets of Quebec just across the provincial border.
A hybrid between an eastern wolf and a coyote. Credit: John Benson
Years of uncertainty
Scientists also dispute the taxonomy of eastern wolves. Previously, some considered them a subspecies of gray wolves (C. lupus), while others argued that they were the result of past hybridization between gray wolves and coyotes. More recently, there has been a general consensus that they are a unique species of wolf native to eastern North America, Benson said. To make things more confusing, regardless of any past hybridization, eastern wolves continue to hybridize with coyotes and Great Lakes wolves.
Benson, then a PhD student at Trent University in Ontario, and his colleagues published a study in 2014 looking at tracking collar data from 2004 to 2011 to determine reasons for deaths in the eastern wolf population. They found that eastern wolves died more from human-related causes outside the boundaries of Algonquin than hybrids or coyotes.
Following this change, the province made efforts to protect wolves in several smaller areas around Algonquin. They expanded the harvesting ban on any wild canids in Algonquin to include Queen Elizabeth II Wildlands, Killarney, and Kawartha Highlands provincial parks starting in June 2016. Despite being provincially protected, the harvest of eastern wolves and their hybrids is still legal nearly everywhere outside Algonquin and those parks.
Benson and his colleagues recently examined a larger dataset comprising nearly two decades of tracking collar, death data taken from necropsies, and field investigations from 2002 to 2020 to see if anything has changed for the species since these efforts were put in place. They published their findings recently in the Journal of Applied Ecology.
Coyotes like this one don’t usually venture into Algonquin as much. Credit: John Benson
Expanded findings
The eastern wolf’s listing didn’t seem to impact whether more or fewer wolves were dying, they found. In addition, the protections offered to eastern wolves in smaller parks like Killarney and Kawartha Highlands haven’t made much of an impact. This is largely because wolves need lots of space, and usually travel beyond the boundaries of these small protected areas during the hunting and trapping seasons, Benson said.
Benson and his colleagues confirmed what they had found earlier in the 2014 paper. While the eastern wolf population in Algonquin was relatively healthy, the canids struggled outside of the park due to a combination of human factors.
Eastern wolf/coyote hybrid pups in a den. Credit: John Benson
The mortality data revealed that eastern wolves died at a higher rate than hybrids, coyotes or other kinds of wolves due to factors like vehicle strikes and hunting. Benson said that roads are a major cause of both factors. Cars strike canids on roads, but they also provide access to hunters and trappers who harvest eastern wolves.
The research also showed that, on an individual level, if a wolf used areas around roads more often, they had a higher chance of dying than individuals that tended to steer clear of them. Lone wolves were also more likely to die than those in packs, likely because they disperse more and cross unprotected areas more.
Outside the park, there are typically larger populations of coyotes and hybrid canids. While these canids are harvested by hunters and struck by vehicles as well, they don’t get killed at the same rate as eastern wolves. Benson said this may be due to the eastern wolves in Algonquin growing up in a protected area and struggling when they leave.
“When they disperse out of the park, they are naïve to human-caused mortality,” he said.
This would include the wolves that may attempt to disperse from Algonquin to a smaller park. To travel between them, the carnivores would have to cross roads and areas where harvesting is permitted. The smaller parks may also not be large enough to protect a wide-ranging carnivore like wolves.
Eastern wolves at a moose (Alces alces) kill. Credit: John Benson
Hybrid issues
But death caused by human factors isn’t the only obstacle to eastern wolf populations dispersing from Algonquin, the team found with previous research. As the wolves leave the park, they enter a world more saturated with coyotes and hybrids. In effect, this means that individuals leaving may be more likely to hybridize, resulting in mixed offspring.
Overall, a combination of a higher chance of death outside Algonquin and a larger chance of hybridizing means that the relatively healthy population of eastern wolves is effectively isolated in the protected area.
This problem is difficult to fix, Benson said. While hunters may not specifically target eastern wolves rather than coyotes or hybrids outside the protected areas, “it would be virtually impossible to make an accurate designation through the sight of a gun,” Benson said, adding that traps wouldn’t discriminate. As a result, a harvesting moratorium on eastern wolves wouldn’t be effective unless it also included moratoriums on hunting and trapping coyotes and hybrids.
A female wolf/coyote hybrid with pups in a den. Credit: John Benson
