Public conservation voting on restoring gray wolves to Colorado

Author contact: Mark Ditmer (mark.ditmer@gmail.com)

Over 3 million voters in Colorado recently weighed in on Proposition 114, a ballot measure to restore the gray wolf to its former range within the state. Previous public opinion polls suggested widespread support for wolf restoration, but the proposition passed with only a slim margin (50.9% of the total vote), and according to new research from Colorado State University scientists, there was a strong relationship between support for the ballot initiative and political support for the Democratic candidate for president in the 2020 election. Additionally, areas closer to proposed wolf restoration areas showed less support for the ballot initiative. Without considering presidential votes, there was a positive relationship between educational attainment and support for wolf restoration. However, when accounting for presidential votes, the team found that voters for President Biden in precincts with lower levels of education had relatively higher levels of support for wolf restoration than voters in precincts with higher educational attainment.

Previous studies have explored the relationships between demographics, livelihood, and self-reported attitudes and beliefs, but few have examined how these factors correspond to actual public behavior, i.e. voting.  

Read the article: Socio-ecological drivers of public conservation voting: restoring gray wolves to Colorado, USA.

Human disturbance is the most crucial factor for lynx in habitat selection

 Habitat selection in wildlife is a process that occurs at different scales: Balancing advantages, such as high abundance of food, with disadvantages, such as human disturbance. Large predators, with their large spatial requirements, are particularly sensitive to these disturbances. A team led by conservation biologists Prof. Dr. Marco Heurich and Joseph Premier from the Faculty of Environment and Natural Resources at the University of Freiburg has studied this habitat selection process in Eurasian lynx. Their results, published by the researchers in Biological Conservation, provide important information for the conservation of this species in human-dominated landscapes. "Through this study, we can generalize the habitat selection behavior of a large carnivore species on a continental scale fort he first time," explains Heurich.

Large dataset with animals in several European areas

The researchers led by Heurich and Premier used a data set consisting of tracking data on 125 lynx from nine study areas across Europe. They compared the locations available to and actually used by the predators at two scales: the landscape scale, which shows how lynx place their home range in the landscape, and the home range scale, which shows how lynx select the habitats within their home range. For this comparison, the research team used a novel machine learning approach called the random forest. This was extended to include a random effect so that variability within and between study areas could be accounted for.

What the animals avoid and how they orient themselves

On the landscape scale the analysis revealed that lynx avoid roads and human settlements. On the level of their home range, the animals were oriented towards hiding places and the availability of prey. The researchers found only minor differences between female and male lynx in their choice of habitat.

Heurich and Premier found the greatest differences in lynx habitat choice at the landscape level, where there were clear differences between the various study areas, for example between the Swiss Alps and the plains of Estonia. Within the foraging areas, lynx behaved very similarly throughout Europe, preferring heterogeneous forest areas and areas that provided protection from human disturbance.

Fishers facing pressure from wildfires, salvage logging,

 

IMAGE: FISHER, MIDSIZE CARNIVORE OF N. AMERICAN FORESTS. view more 

CREDIT: OREGON DEPARTMENT OF FISH AND WILDLIFE

. – The recovery of the fisher, a charismatic, long-tailed forest carnivore, will likely be hindered by the increasing frequency and intensity of future wildfires, new research by Oregon State University indicates.

A long-term monitoring program along the Oregon-California border showed that fisher abundance declined following three mixed-severity wildfires and that salvage logging also affected fisher populations negatively, said David Green of the OSU Institute for Natural Resources.

“We estimated a 27% reduction in the total number of fishers within our study area following the fires,” added Green, who led the study published today in Ecosphere.

Fierce and secretive, the fisher is an animal of conservation concern whose numbers dwindled in the 19th and 20th centuries due to fur trapping and logging. It’s a member of the Mustelidae family, which also includes wolverines, badgers, otters and minks, and it is native only to Canada and the northern United States.

“The fisher has a limited distribution, and rapid changes to forest structure could threaten its long-term persistence,” Green said.

Despite what they are called, fishers don’t prey on fish. They are so named because early North American settlers noticed a resemblance to the European polecat, which was also called a fitch, fitchet or fitchew.

Roughly the size of a large house cat, fishers not only scale trees but are able to climb down headfirst thanks to hind feet that can rotate almost 180 degrees. That trick helps them carry their offspring in their mouths as they climb up and down trees and may also help them attack prey from above.

The largest fisher population in the western United States is in what scientists refer to as the Klamath-Siskiyou Ecoregion, a 50,000-square-kilometer area straddling the Oregon-California border that has an estimated fisher density of about six per 100 square kilometers.

The researchers monitored fishers and gray foxes on a 465-square-kilometer portion of the ecoregion and examined the impacts of three mixed-severity wildfires – the Beaver, Gap and Happy Camp Complex fires – that burned 26% of the area in the summers of 2014 and 2016.

“A century of fire suppression plus increasingly frequent and long periods of drought are predicted to lead to more frequent and more intense wildfires across the West,” Green said. “Understanding the effects of wildfire on the species that live in forests, and the interactions among species, is important for making the most effective conservation and management decisions. The short- and long-term consequences are unclear for wildlife amid the calls for restoring forests to their natural regimes of frequent, low-severity fires.”

Wildfires, especially high-severity fires, cause vegetation changes that can make an area uninhabitable, he said. Salvage logging and replanting add more layers of complexity and make it harder to understand how wildlife respond to wildfire.

Green and collaborators from OSU, North Carolina State University and the U.S. Forest Service used six years of data from a long-term monitoring program to analyze the effects of fire and salvage logging on a population of fishers as well as a population of gray foxes.

Gray foxes are similar in size to fishers and compete with them for prey. Determining the effects of wildfires on gray fox populations and understanding how gray foxes and fishers interact is important for fisher conservation, Green said.

“Fisher abundance decreased significantly in areas of low-, medium- and high-severity wildfire,” he said. “Gray fox abundance decreased in the years before the wildfires but then rebounded.”

Abundance refers to a species’ relative representation in a particular ecosystem – in this case, how many fishers and foxes there are in the study area compared to other animals who share the area.

The researchers also looked at population density – the number of animals per unit of area. They found that medium-severity wildfires had a negative effect on gray fox density but high-severity fire had a positive effect. Salvage logging negatively affected both fisher and gray fox density, the study showed.

“Our results suggest that increased severity, extent and frequency of wildfires in the western United States will have negative impacts on fisher populations and change community composition for medium-size predators,” Green said. “We found that the wildfires that occurred in the Klamath-Siskiyou Ecoregion affected fisher density negatively regardless of burn severity, while gray fox density decreased in areas that burned at medium severity and increased in areas that burned at high severity.”

The researchers aren’t sure why the different severity levels had differing impacts on the two animals studied. More information on the long-term effects of fire and salvage logging on carnivores is needed, Green said, especially regarding changes in survival or reproduction.

New research shows that the effects of wolves on the recovery of aspen has been exaggerated by how it was measured

Peer-Reviewed Publication

S.J. & JESSIE E. QUINNEY COLLEGE OF NATURAL RESOURCES, UTAH STATE UNIVERSITY

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IMAGE: PREVIOUS RESEARCH SHOWED STRONG POSITIVE GROWTH IN YOUNG ASPENS IN YELLOWSTONE NATIONAL PARK AS THE ELK POPULATIONS DECREASED—A WELCOME RESULT. BUT NEW RESEARCH SHOWS ASPEN RECOVERY IS NOT AS ROBUST AS PREVIOUSLY THOUGHT. view more 

CREDIT: PHOTO COURTESY LAINIE BRICE

It’s an environmental success story that feels like a parable—the reintroduction of wolves in Yellowstone National Park in the mid-1990s triggered a cascade of effects that ultimately restored the ecosystem, including the recovery of aspen trees. But like many stories based on ecological realities, it’s more complex than at first glance—aspen recovery in the park is not as robust as generally believed, according to new research.

The Yellowstone story is a textbook example of a trophic cascade, in which predators help plants grow by eating or scaring away herbivores that eat the plants. When wolves were reintroduced into the Yellowstone food chain, they helped to reduce numbers of elk, which had been consuming young aspen trees. Previous research showed strong positive growth in young aspen as the elk populations decreased—a welcome result, as aspen forests have been vanishing from the northern Yellowstone landscape for the last century.

But new research from Elaine Brice and Dan MacNulty, from Utah State University’sDepartment of Wildland Resources and Ecology Center, and Eric Larsen, from the University of Wisconsin Stevens Point’s Department of Geography and Geology, shows that the effect of wolves on the recovery of aspen has been exaggerated by how it was measured.

Previous studies evaluated aspen recovery in Yellowstone by measuring the five tallest young aspen within a stand. The reasoning was that the tallest young aspen trees represent a ‘leading edge’ indicator of the future recovery of the entire aspen population. But this is not the case—sampling only the tallest young aspen estimated a rate of recovery that was significantly faster than was estimated by random sampling of all young aspen within the stand, according to the research.

“These are extremely complex systems, and understanding them is a major challenge because they are difficult to properly sample,” said Brice. “The traditional method of sampling by only using the tallest young aspen plants to measure growth—which most research currently relies on—doesn’t capture the entire picture.”

For one, elk are picky about the aspen they consume. They tend to eat plants at shoulder height for which they don’t have to crane their necks. As the leader stem (main trunk) of a young aspen grows past the shoulder height of adult elk, it is decreasingly likely to be eaten as it grows taller, said MacNulty. “This means that the tallest young aspen grow faster because they are taller, not because wolves reduce elk browsing,” said MacNulty. This finding highlights the complicating fact that height of young aspen is both a cause and an effect of reduced elk browsing. 

Taller aspen also thrive because they tend to have the best growing conditions (sunlight, moisture, soil quality). Measuring just the tallest young trees downplays the role of these other factors that have nothing to do with elk or wolf populations. And measuring just the tallest aspen also overlooks the failure of some young aspen to regenerate in the first place.

“That’s like calculating a team’s batting average without the player who always strikes out,” said Brice. Random sampling from the research showed an absence of aspen regeneration in some places, a vital piece missing from the initial measurements.

Understanding how ecosystems respond to changes in large predator populations is vital to resolving broader debates about the structure of food webs, determining species abundance and delivering ecosystem services, said the authors. This study demonstrates how deviations from basic sampling principles can distort this understanding. Non-random sampling overestimated the strength of a trophic cascade in this case, but it may underestimate cascading effects in other situations. Randomization is one of the few protections against unreliable inferences and the misguided management decisions they may inspire, they said.

“The bottom line is that ecologists must stick to classic principles of sampling design, like randomization, to fully understand trophic cascades in complex wildlife systems like Yellowstone,” said MacNulty.

Carnivore interactions are a game of risk and reward

 Coyotes can eat by scavenging cougars' prey but it's a risky proposition as coyotes often end up killed by cougars too, a new study of predator interactions by Oregon State University shows.

Researchers in the OSU College of Agricultural Sciences also looked at black bears and bobcats and found the interplay within the four-species "guild" of predators defied simplistic description.

Findings, published today in the Proceedings of the National Academy of Sciences, challenge the traditional model for carnivore interactions among species: that dominant predators suppress the other ones.

The study, one of the first to quantify rates of both scavenging and intraguild predation, is important because understanding the influence of dominant predators is necessary for anticipating the ecological effects of changes in carnivore populations.

Factoring in the study area's cougar and coyote density, the findings suggest nearly one-quarter of the area's coyote population is killed by cougars each year, although in many cases, coyotes did not appear to be killed while scavenging.

"That kill percentage estimate implies a strong suppressive effect counteracting the benefit to coyotes provided by the cougars," said Oregon State Ph.D. student Joel Ruprecht. "Overall, the issue of whether subordinate species incur a net fitness cost or benefit from dominant predators is far from resolved."

Coyotes seem to readily accept the risk of being near a cougar if a food reward is available, possibly because they can manage the risk by being extra vigilant, he added. Also, if a dominant predator becomes satiated after feeding on a kill, it may not be motivated to kill other carnivores.

"Learning whether dominant carnivores kill subordinate carnivores for food or for the long-term benefit of removing a competitor needs to be the focus of further research," said OSU associate professor Taal Levi.

Ruprecht, Levi and Ph.D. student Charlotte Eriksson led the study, which also involved scientists from the Oregon Department of Fish and Wildlife, the U.S. Forest Service and the University of California, Santa Cruz.

Between 2016 and 2020 in the Blue Mountains of northeastern Oregon, researchers tagged a "guild" of predators -- 17 cougars, 17 coyotes, 11 black bears and six bobcats -- with GPS collars that recorded their location every few hours. Scientists also tested the animals' scat to see what they were eating.

"How often elk turns up in the scats of the subordinate predators is a proxy for how much scavenging they're doing because it's unlikely any of them are killing adult elk," Levi said. "That means if they're eating elk it's probably either via scavenging or preying on calves, but in the Blue Mountains coyotes and bobcats rarely kill elk calves; black bears are somewhat more likely to."

To further zero in on what the predators were eating, the scientists did ground searches based on clusters of cougar GPS locations -- indicating potential kills -- and set up cameras at 28 of the 128 confirmed kill sites. The cameras allowed for a daily tally of site visits by bears, bobcats and coyotes and thus enabled an estimate of scavenging rates.

"The traditional paradigm for species interactions among carnivores has stressed hierarchies: Dominant predators curb the efforts of the next level, the mesopredators," Levi said. "We found evidence of that but also evidence of facilitation. The coyotes we studied had a strong attraction to kill sites, frequent carrion in their diet and high scavenging rates, compared to two indicators of suppression: They avoided cougars and also were preyed on by them."

There was no evidence to suggest coyotes' attraction to kill sites was lessened if a cougar was around, he added, indicating coyotes' willingness to disregard cougar risk if a food reward was present.

Bears had moderate scavenging rates and ate moderate levels of carrion but showed a statistically significant aversion to being around cougars. Nothing suggested bears were particularly attracted to kill sites or suffered predation at the hands of cougars, or that cougars had any effect at all on bobcats.

"Bobcats were indifferent to both cougars and their kill sites," Ruprecht said. "And bobcats weren't avoiding coyotes in general, meaning coyote presence was probably not a primary reason bobcats didn't feed on cougar kills."

There were coyotes on the scene at 89% of carcasses, bears at 50% of carcasses outside the hibernation period and bobcats at none of them.

Scat analyses showed elk in 58% of coyote scats and deer in 12%, comparable to the percentages for cougar scats (61% and 22%). Bear scats contained elk 29% of the time and deer 8% of the time. No bobcat scats provided evidence they had eaten elk, and 8% of bobcat scats contained deer.

"Investigations of the cougar kill sites showed that elk represented 64% and deer 16% of the prey items killed by cougars," Levi said. "Investigations also showed that coyotes represented 7% of cougar kills. In eight cases coyotes were the only prey item found, and in one case a dead coyote was found along with another prey item."

The bobcat findings were particularly surprising, he noted, because bobcats are known to scavenge from and be eaten by cougars in other locations, and also because it's usually more likely for a wild cat like a cougar to kill another species of cat than a predator from outside their taxonomic family.

"By foregoing the energy benefits they could gain from eating on cougar kills, and in doing so reducing mortality risk, bobcats in our study area approached the risk-reward tradeoff quite differently than the coyotes," he said. "But scavenging is only optimal under a specific set of conditions that also includes the probability of finding other food sources, and the energy required to search for them. The coyotes we studied faced little risk except from cougars and scavenged profusely; they're probably less likely to scavenge when there are lots of competitors for each carcass."

Southeast’s gray foxes may be struggling for survival

Competition for food from coyotes seems to be key to declining populations

Peer-Reviewed Publication

UNIVERSITY OF GEORGIA

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IMAGE: GRAY FOX POPULATIONS SEEM TO BE DECLINING IN THE SOUTHEAST, ACCORDING TO UNIVERSITY OF GEORGIA RESEARCH. view more 

CREDIT: SARAH WEBSTER

For generations, gray foxes have been part of the Southeastern landscape. They, along with red foxes, are among the carnivores that dine on a range of smaller animals, plants and berries.

But a new study published by researchers from the University of Georgia suggests competition for food from coyotes—a relative newcomer to the Southeast—may be putting pressure on foxes, particularly the gray fox.

“Gray fox populations, especially in the Southeast, seem to be declining, and have been for some decades,” said James Beasley, an associate professor in the UGA Warnell School of Forestry and Natural Resources whose doctoral student, Sarah Webster, wrote the study as part of her dissertation.

The study, published in the Journal of Mammology, was co-authored by Beasley as well as Warnell professor Michael Chamberlain and Warnell alumnus Joseph Hinton.

By looking at reports given by licensed animal trappers in South Carolina, where Beasley’s lab is located, it was clear to the researchers that the number of harvested foxes—particularly gray foxes—has been decreasing, while the number of harvested coyotes has increased.

“Here on the Savannah River Site, there are excellent historical trapping records and gray foxes used to be really abundant,” said Beasley. “But now we don’t see them nearly as frequently. That’s prompted questions of why—why are we seeing the reduction in these numbers?”

At the Savannah River Ecology Lab in Aiken, South Carolina, where the study took place, Beasley said habitats have changed dramatically over the years, from agricultural areas preferred by red foxes to forested areas more conducive to tree-climbing gray foxes. Also, food is abundant for generalist carnivores such as coyotes and foxes, which will eat a variety of plants and animals, and coyotes are now abundant in this landscape.

In the Midwest, where foxes and coyotes have lived together for hundreds of years, the species have found a way to carve out food sources without overlapping too much—scientists call this “partitioning.” But coyotes have only been in the Southeast since the 1970s, giving them far less time to sort out their overlapping food preferences.

Still, Webster wanted more information about how coyotes’ and foxes’ food sources might differ between the regions. So, she used hair samples gathered from red and gray foxes and coyotes from both regions and from a variety of decades, including preserved samples from the Georgia Museum of Natural History. By measuring the amounts of carbon or nitrogen in the hair, Webster was able to assess the amount of overlap in diet between each species.

For example, a diet high in protein would manifest as a higher nitrogen content. Vegetation, such as fruits or grasses, translates as carbon in the hair samples. By noting the relative amounts of carbon and nitrogen content in hair samples, Webster was able to assemble a picture of how much diet overlap there was between each species in each region.

The results? There are significant regional differences in how coyotes and foxes dine.

“In the Midwest, we found there were significant differences in diet between species, whereas in the Southeast they overlapped significantly,” she said. In the Southeast, red and gray foxes had a large amount of overlap in their diets prior to the onset of coyotes, and that overlapping continued once coyotes arrived, according to more recent samples. “So, all three species are overlapping now in the Southeast.”

Beasley noted that the diet partitioning that takes place among these species in the Midwest is something that developed over hundreds of years, as coyotes and foxes learned to navigate the landscape around each other. There apparently hasn’t been enough time for that dynamic to play out in the Southeast.

“The question is, will that happen fast enough, before the gray fox populations continue to decline further?” he added. “It’s not exceptionally dire for the gray fox, but we now often find them closer to buildings or other marginalized areas. So, they may be finding other mechanisms to coexist with coyotes. But they do need forested areas.”

Habitat is one way, said Webster, that we can work to ensure future populations of gray foxes remain stable. When we understand the dynamics at play between the species, we can better plan for the future.

“We don’t have good evidence that we can effectively manage coyote populations on a large scale. They’re generalists, and they’re too flexible in their behavior and patterns. They will survive just fine,” said Webster. “So, a more effective approach likely would be to focus on the gray fox. Step one is to better understand how the gray fox population is doing by studying their population dynamics, and then going forward from there and trying to build effective management around the gray fox to ensure they continue to thrive in the Southeast.”

DNA assay aids in identifying and protecting North American wolves, coyotes

NORTH CAROLINA STATE UNIVERSITY

Research News

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Forensics specialists can use a commercial assay targeting mitochondrial DNA to accurately discriminate between wolf, coyote and dog species, according to a new study from North Carolina State University. The genetic information can be obtained from smaller or more degraded samples, and could aid authorities in prosecuting hunting jurisdiction violations and preserving protected species.

In the U.S., certain wolf subspecies or species are endangered and restricted in terms of hunting status. It is also illegal to deliberately breed wolves or coyotes with domesticated dogs.

"If it's a case where you have a whole specimen, authorities can typically identify it based on physical characteristics, though similarity between some species makes that method less than ideal," says Kelly Meiklejohn, assistant professor of forensic science at NC State and corresponding author of the research. "If you're working with cross-bred animals, or incomplete specimens, you need DNA-based methods to accurately determine what species you have."

Although some U.S. federal laboratories perform DNA-based identification of wolves and coyotes, their methods and genetic reference databases aren't publicly available. Meiklejohn partnered with the U.S. Fish and Wildlife Service to see if it was possible to use a commercially available assay designed for dogs as a way to recover the mitochondrial genome from diverse North American canid species.

The mitochondrial genome is one of two genomes inherited from an animal's parents. Specifically, the mitochondrial genome is inherited from the mother. It is useful for species identification both because its circular shape makes it less prone to degradation, and because there are more copies of this genome per cell, increasing the chance of retrieving useful material from small or damaged samples.

The team used a method, called a 'hybridization capture,' in which about 80 base-pair long RNA fragments are used to isolate DNA for sequencing. Samples are incubated with the RNA fragments, and if there's a match, the fragment will bind with the sample's DNA. The bound DNA can be isolated and sequenced. In this case, the team used a hybridization capture panel designed for the dog mitochondrial genome.

"The fragments will bind if there is about 80% similarity, which is why we felt the dog kit would be useful for sequencing wolves and coyotes," Meiklejohn says. "Dogs only diverged from wolves around 20,000 years ago, so the mitochondrial genomes aren't that different."

They sequenced 51 samples, and were able to recover full mitochondrial genomes and successfully differentiate between four species of interest: dog, wolf, Mexican wolf, and coyote.

"Essentially, this finding means we can do more with less," Meiklejohn says. "In forensics we rarely have high quality DNA samples; they've usually been exposed to the environment and are degraded. The flexibility of this kit allows us to determine the species we're looking at, which in turn may aid in prosecuting hunting or breeding violations and protecting endangered canid species."