Black bears may play important role in protecting gray fox

UNIVERSITY OF NEW HAMPSHIRE

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DURHAM, N.H.-- Bears are known for being devoted and protective of their baby cubs, but research from the University of New Hampshire shows that they may also play a significant role in shielding gray fox from predators like coyotes, who compete with the fox for food and space. The research is one of the first studies to show how black bears provide a buffer to allow other, smaller carnivores to safely co-exist.

"Even though black bears and coyotes are the two most common carnivores in North America, we're still learning how they affect the ecosystems around them," said Rem Moll, assistant professor of wildlife ecology and lead author of the study. "What's unique about bears is that they hibernate, so they literally disappear for half a year, which we now know can shift animal habits in the ecosystem."

In the study, published in the journal Oecologia, researchers took a closer look at the hierarchy of carnivores to see if a major life trait, like hibernation, had a significant effect. In the western part of Nevada, near Lake Tahoe, the researchers tracked and monitored the top species of carnivores which included black bears, which are the largest and most dominant species, followed by coyotes, bobcats, and finally gray fox, which are the smallest (a bit larger than a cat) and most subordinate species. They found that in summer the gray fox stayed close to areas populated by black bears which appeared to provide a top-down buffering effect helping to protect the gray fox from the coyotes. But in the winter, when bears were hibernating, this pattern reversed and coyotes were three times more likely to move into the now vacant bear territories and the gray fox, no longer secure by the presence of the black bear, moved out. This pattern suggests that the top carnivore - black bears - provided a shield for the gray fox from competition with coyotes. But this "bear shield" was only seasonal, disappearing when the bears hibernated.

"In our field of research, there is something called the "landscape of fear" - the idea that there is a pecking order and that both predators and prey will change their behavior to avoid getting killed," said Moll. "For decades this was overlooked, so there aren't a lot of studies showing the connection between black bears and coyotes - two of the most common carnivores in the U.S. - but this work suggests that fear is important in defining the species roles in the ecosystem."

The researchers say even though this study was done near Lake Tahoe, where black bears were nearly extinct a few decades ago, they believe these instinctual actions could be a very common dynamic in any area where black bears, gray fox and coyotes co-exist.

Cultural, belief system data can inform gray wolf recovery efforts in US

COLORADO STATE UNIVERSITY

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IMAGE: NORTH DAKOTA, WYOMING AND MONTANA HAVE MORE RESIDENTS WITH TRADITIONALIST VALUES, SAID MICHAEL MANFREDO, LEAD INVESTIGATOR AND DEPARTMENT HEAD OF THE DEPARTMENT OF HUMAN DIMENSIONS OF NATURAL RESOURCES. view more 

CREDIT: CSU PHOTOGRAPHY

Humans regularly exert a powerful influence on the survival and persistence of species, yet social-science information is used only sporadically in conservation decisions.

Researchers at Colorado State University and The Ohio State University have created an index depicting the mix of social values among people across all 50 states, providing data that can be useful for wildlife conservation policy and management.

As a specific illustration, the research team found a supportive social context for gray wolf reintroduction in Colorado. Last fall, citizens in the state voted by ballot initiative to mandate the reintroduction of gray wolves. The data and maps in the study reveal that Colorado's social environment is far more conducive to wolf recovery than states like Montana and Idaho, which currently have state legislative efforts to reduce wolf populations.

The study, "Bringing social values to wildlife conservation decisions," was published online June 3 in Frontiers in Ecology and the Environment.

Michael Manfredo, the study's lead investigator and head of CSU's Department of Human Dimensions of Natural Resources, said the research reveals how people fall into the categories of traditionalists - those who believe animals should be used for purposes that benefit humans, like hunting and medical research - or mutualists, those who believe that animals deserve the same rights as humans. Mutualists view animals as companions and part of their social networks and project human traits onto animals.

"You can see what the 'flavor' is of the state or county, and what policies or initiatives people are likely to support or be opposed to," said Manfredo.

Highly modernized states, including California, Nevada, Colorado and Washington, are leaning more toward mutualism, according to the research. North Dakota, Wyoming and Montana have more residents with traditionalist values.

Tara Teel, CSU professor and a lead author on the study, said that the data is relevant for other hot and new topics and drills down to the county level.

"This study builds on a 50-state study on America's Wildlife Values -- the largest and first of its kind," said Teel. "It is one of the first broadly accessible social science datasets to inform wildlife conservation efforts across the United States."

Data provides insight on conservation decisions

While the results are particularly relevant for the U.S., the technique used by the team could be applied to better account for human factors in conservation decisions for addressing issues like climate change, species reintroductions and human-wildlife conflict globally.

The research team used data from a survey conducted from 2017 to 2018 of 46,894 U.S. residents and applied a sociocultural index to inform decision-making through an understanding of public values toward wildlife. Scientists measured mutualist and traditionalist values, which have previously been shown to be highly predictive of attitudes on a wide range of policy issues. The team subsequently developed state and county maps.

'Values don't change quickly'

"Previous research has found that there is a strong relationship between the laws passed in any given state and people's values," said Manfredo. "In the last two decades, there's been a substantial change in how people value wildlife," he added.

"Values don't change quickly," he said. "They're not like how a person feels about political issues. Values are formed in a person's youth and stay with you forever."

Manfredo said data showed that as far back as the early 2000s, people in Colorado were in favor of wolf reintroduction. But in places like Jackson County, a sub-alpine valley in northern Colorado, people were not so excited about wolves.

"Society is changing, and there's been a backlash from traditionalists who feel that their values and their voices in decision-making are being threatened," he said. "Ultimately, state and local agencies need to pay more attention to constituents. That means everybody in the state, not just a segment or a particular county. Policies need to fall more in line with the values of the public."

Researchers uncover hidden hunting tactics of wolves in Minnesota's Northwoods

 

In first systematic analysis of their ambushing behavior, U of M researchers find wolves' hunting strategies are highly-flexible depending on their prey.

UNIVERSITY OF MINNESOTA

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IMAGE: IN A NEW PAPER PUBLISHED IN THE JOURNAL BEHAVIORAL ECOLOGY, , RESEARCHERS FROM THE UNIVERSITY OF MINNESOTA AND THE VOYAGEURS WOLF PROJECT SHOW THAT WOLVES HAVE EVOLVED AMBUSH HUNTING TACTICS... view more 

CREDIT: VOYAGEURS WOLF PROJECT

Wolves are arguably the most well-studied large predators in the world, yet new research shows there is still a lot to learn about their hunting tactics. Typically, wolves hunt large mammals like moose, deer, and bison in packs by outrunning, outlasting, and exhausting their prey. However, throughout the dense boreal forests in North America and Eurasia, during the summer wolves often hunt beavers by themselves.

But how does a wolf catch a semi-aquatic prey that spends little time on land and never ventures far from the safety of its pond? Turns out with patience, and a lot of waiting.

In a new paper published in the journal Behavioral Ecology, researchers from the University of Minnesota and the Voyageurs Wolf Project--which studies wolves in the Greater Voyageurs Ecosystem in the northwoods of Minnesota--show that wolves have evolved ambush hunting tactics specifically tailored for catching and killing beavers.

"Over a five-year period, we estimate that our field research team collectively put in over 15,000 person-hours to search nearly 12,000 locations where wolves had spent time. Through this effort, we ended up documenting 748 locations where wolves waited to ambush beavers but were unsuccessful, and 214 instances where wolves killed beavers," said Sean Johnson-Bice, a co-author of the study. "This dedicated fieldwork has provided unprecedented insight into the hunting tactics wolves use in boreal environments."

Beavers have extremely poor eyesight, so they rely primarily on their well-developed sense of smell to detect predators on land--and wolves appear to have learned this through time. Researchers discovered wolves choose ambushing sites within a few feet of where beavers are active on land because wolves have learned beavers cannot visually detect them. When doing so, wolves almost always choose ambushing sites that are downwind to avoid being smelled by beavers.

"The results are very clear," said Tom Gable, the study's lead-author: "89-94% of the ambushing sites were downwind, where beavers were likely unable to smell wolves."

When staking out beavers, wolves appear to be surprisingly patient. They spend substantial periods of time waiting next to areas where beavers are active on land, such as near beaver dams and trails.

"Wolves waited an average of four hours during each stakeout. But they often waited eight-12 hours or more, and one wolf even waited-in-ambush for 30 hours," said study co-author Austin Homkes.

The researchers note that these behaviors were not unique to a few wolves. Instead, wolves from multiple packs across several years used the same ambushing tactics, indicating that this behavior is widespread throughout the Greater Voyageurs Ecosystem and likely other ecosystems where wolves hunt beavers. Notably, wolves and beavers co-occur across much of the Northern Hemisphere so the implications have wide applicability.

"Gathering data to demonstrate how wind direction influences the ambushing behavior of predators has been difficult for animal ecologists," said co-author Joseph Bump. "Scientists have long-thought that ambush predators are able to strategically choose ambush sites in areas where prey are unable to detect them via scent. Until now though, documenting these hunting tactics in exhaustive detail proved extremely challenging."

Ultimately, the study challenges the classic concept that wolves are solely cursorial predators (i.e., predators that kill their prey by outrunning and outlasting them). Instead, wolf-hunting strategies appear highly flexible, and they are able to switch between hunting modes (cursorial and ambush hunting) depending on their prey.

"It is the first systematic analysis of wolf ambushing behavior," said Gable. "It overturns the traditional notion that wolves rely solely on hunting strategies that involve pursuing, testing, and running down prey."

New challenges for wolf conservation

People view the wolf as either a threatening predator or a sign of a healthy natural habitat. Many proponents of nature and animal conservation welcome the spread of wolf populations in Germany. By contrast, farmers who graze herds directly impacted by the wolves' return are more critical. The team of Nicolas Schoof, Prof. Dr. Albert Reif of the Chair of Site Classification and Vegetation Science at the University of Freiburg, and Prof. Dr. Eckhard Jedicke of the Competence Center Cultural Landscape and the Department of Landscape Planning and Nature Conservation of Hochschule Geisenheim University has assessed the existing legal situation. On the basis of a range of environmental data they have determined the conflicts and drawn up possible solutions. In an article in the German specialist journal "Naturschutz und Landschaftsplanung" (Nature Conservation and Landscape Planning) the researchers present in detail how wider distribution of the predator could negatively affect legally binding nature conservation goals.

Schoof explains that experts - based on the assumption that the wolves were living mainly in isolation - initially ascribed those that have reappeared in Germany to the Central European Lowlands population. Nevertheless, newer genetic studies show the population is at least interacting with the Baltic wolf population, meaning that incest risk is low. The Freiburg researcher goes on to say that European law is very strict and does not allow - other than has been often maintained - any type of regulatory culling. "As a result," says Schoof, "there is a high growth and survival rate for young animals, allowing the wolf to spread to many regions."

The species itself primarily indicates there has been growth in the native fauna. Schoof's team is analyzing the consequences the growing wolf population - and with it the increasing attacks on livestock and resulting demands to protect herds in Germany - will have for maintaining biodiversity. "There's the threat of a partial abandonment of livestock grazing, especially in locations that are crucial to conserving nature," explains Schoof. Areas affected could, for example, be meadows or grasslands on steep slopes as well as those with stony soils. These habitats are - like the wolf itself - the focus of legally binding conservation measures and are dependent on the continuation of grazing. Unlike the wolf habitats, these environments are so rare that they are at risk.

In many cases, new fences can offer herds much better protection. But this isn't possible on steep slopes, for example. Dependent on the size and condition of the pastures, sheepdogs could be introduced. But the researchers say that is a markedly labor and cost intensive option which would only come into question for a few livestock owners. But sheepdogs cannot be effectively used above all in partially open pasture lands that are an essential component for conserving biodiversity. Yet it is precisely in these areas that the problems caused by wolves could increase, says Schoof, meaning that only fixed, wolf-resistant fences are a solution, but these would limit the spatial efficacy of large grazing projects. What is more, the expected erection of fencing systems will generally form a massive impediment to other wildlife that have found an optimal habitat on grazing land.

Based on these conflicts, the researchers say they have no doubt that the permissible legal regulatory measures to cull problematic individuals through hunting must be simplified significantly and stringently implemented. Taken in perspective, comprehensive active management of the wolf population must be considered and the necessary legal regulatory changes undertaken. The researchers argue that the wolf population is not endangered because of the individual numbers that have been reached, the generally low incest risk, and the current exponential growth in population. Schoof points out that simpler solutions are not in sight or legally possible as yet.

Additionally, the researchers propose in their study that on the one hand, all the required measures to protect herds should be comprehensively supported. "On the other hand, better financial support for the frequently economically unattractive farming of grazing animals could contribute to moderating the existing conflicts," says Schoof. "In that way, owners of grazing livestock would clearly be shown that they are key partners when it comes to implementing practical conservation efforts," he adds.

Wolves affect wetland ecosystems by killing beavers leaving their colonies to create new ponds.

 

Beavers are some of the world's most prolific ecosystem engineers, creating, maintaining and radically altering wetlands almost everywhere they live. But what, if anything, might control this engineering by beavers and influence the formation of North America's wetlands?

In a paper to be published Friday in the journal Science Advances, researchers with the University of Minnesota's Voyageurs Wolf Project and Voyageurs National Park observed and demonstrated that wolves affect wetland ecosystems by killing beavers leaving their colonies to create new ponds.

Beavers are important ecosystem engineers that create wetlands around the world, storing water and creating habitat for numerous other species. This study documents that wolves alter wetland creation when they kill beavers that have left home and created their own dams and ponds.

Juvenile beavers disperse alone and often create new ponds or fix up and recolonize existing, old ponds. By studying pond creation and recolonization patterns along with wolf predation on beavers, project biologists and co-authors Tom Gable and Austin Homkes found that 84% of newly-created and recolonized beaver ponds remained occupied by beavers for more than one year. But when a wolf kills the beaver that settles in a pond, no such ponds remain active.

This relationship between wolves and dispersing beavers shows how wolves are intimately connected to wetland creation across the boreal ecosystem and all the ecological processes that come from wetlands.

"How large predators impact ecosystems has been a matter of interest among scientists and the public for decades," said Gable, project lead of the Voyageurs Wolf Project. "Because wolves are the apex predators in northern Minnesota and beavers are ecosystem engineers, we knew there was potential for wolves to affect ecosystems by killing beavers."

Researchers found that wolves can have this impact on wetlands without necessarily changing the abundance or behavior of beavers. This newly supported link between wolf predation, dispersing beavers and wetlands may have long-lasting impacts for boreal landscapes and habitat for other species. The Voyageurs Wolf Project is investigating the long-term effects of this relationship.

"In 2015, we documented a wolf killing a dispersing beaver in a newly-created pond," said Homkes, a field biologist with the Voyageurs Wolf Project. "Within days of the wolf killing the beaver, the dam failed because there was no beaver left to maintain it. The wolf appeared to have prevented the beaver from turning this forested area into a pond. This initial observation was fascinating and we realized we needed to figure out how wolves were connected to wetland creation in the Greater Voyageurs Ecosystem."

After five years of intensive fieldwork, Gable, Homkes and colleagues have estimated that wolves altered the establishment of about 88 ponds per year and the storage of over 51 million gallons of water annually in the Greater Voyageurs Ecosystem. The pond observed in 2015 still has not been colonized by another beaver, said Gable, who visited the site in mid-September 2020.

"Our work hints at the possibility that wolves might have a longer-term impact on wetland creation and generate habitat patchiness that supports many other species across the landscape, but we need to study this mechanism further," said Joseph Bump, co-author and associate professor in the University's Department of Fisheries, Wildlife, and Conservation Biology.

Wolves and large predators are usually thought to have outsized ecological effects primarily by reducing the abundance of their prey or by altering the behavior of their prey through fear of predation, both of which allow predators to indirectly impact lower parts of the food chain such as vegetation, songbirds and other wildlife. Some research has even claimed wolves impact river ecosystems through trophic cascades, but this has been met with substantial skepticism and remains hotly debated among scientists.

"The fact that we have convincingly shown wolves can impact wetlands without necessarily changing the abundance or behavior of beavers is a really exciting finding," said co-author Sean Johnson-Bice, a project collaborator from the University of Manitoba.

"The Greater Voyageurs Ecosystem sits within a flat landscape that is dominated by water and trees, creating the perfect conditions that currently support some of the highest beaver densities in North America," said Voyageurs National Park wildlife researcher and co-author Steve Windels.

"Though we don't have evidence that wolves are limiting the size of the beaver population in Voyageurs, understanding the nuanced and complex ways that predators and prey affect one another and their environment is critical to fulfilling the National Park Service's mission to protect and preserve our resources for future generations."

This study identified a novel and unique way by which predators influence ecological processes, which ultimately enriches our understanding of the diverse roles predators play in ecosystems.

"There are a number of good reasons to maintain and restore healthy predator populations and this study should be helpful for understanding the full role and therefore value of predators, especially when they eat ecosystem engineers," Bump said.

What does the fox say to a puma?

VIRGINIA TECH

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IMAGE: PUMAS ARE THE TOP PREDATORS IN THE STUDY RESEARCH AREA IN THE CHILEAN ANDES. CAMERA TRAP PHOTO BY CHRISTIAN OSORIO. view more 

CREDIT: CHRISTIAN OSORIO

In the high plains of the central Chilean Andes, an ecosystem consisting of only a few animal species is providing researchers with new insights into how predators coexist in the wild.

"The puma and the culpeo fox are the only top predators on the landscape in the Chilean Andes," said Professor Marcella Kelly, of the College of Natural Resources and Environment. "And there isn't a wide range of prey species, in part because the guanacos [closely related to llamas] aren't typically found in these areas anymore due to over-hunting. With such a simplified ecosystem, we thought we could really nail down how two rival predators interact."

Kelly worked with Christian Osorio, a doctoral student in the Department of Fish and Wildlife Conservation, and researchers from the Pontifical Catholic University of Chile to chart the locations of and potential interactions between pumas and foxes in central Chile. They focused on three axes of interaction: spatial (where the animals are on the landscape), temporal (the timing of specific activities on a given landscape), and dietary (what each species is eating).

To understand the interplay between pumas and foxes, researchers deployed 50 camera stations across two sites in central Chile, one in the Rio Los Cipreses National Reserve and another on private land where cattle and horses are raised. They also collected scat samples at both locations to analyze the diets of pumas and foxes.

The team's findings, published in the journal Diversity, showed that while pumas and foxes overlapped significantly where they lived and what time they were active, there was little overlap in what they were eating, with the puma diet consisting primarily of a large hare species introduced from Europe, while the culpeo foxes favored smaller rabbits, rodents, and seeds. The two predator species can successfully share a landscape and hunt for food over the same nighttime hours because they are, in essence, ordering from different menus.

"It is likely that foxes have realized that when they try to hunt hares, they might run into trouble with pumas," Osorio explained. "If they are hunting smaller mammals, the pumas don't care, but if the foxes start targeting larger prey, the pumas will react."

How predator species interact is a crucial question for ecologists trying to understand the dynamics that inform ecosystem balances. And while the puma has been designated a species of least concern, the animal's populations are declining and continue to be monitored by conservationists.

"Least concern does not mean no concern," Osorio noted. "We have laws in Chile that protect the species, but the data we have to make a conservation designation are very scattered. As we accumulate more consistent and reliable data, the puma may be reclassified as vulnerable or even endangered."

The hares that comprise approximately 70 percent of the biomass in the puma's diet are a nonnative species, introduced to the area by European settlers. With guanacos absent from the landscape, the puma has had to adapt its diet to survive.

With some land managers and conservationists campaigning for the removal of the introduced hare species as a way to restore the area's native ecosystem, Kelly and Osorio note that it is important to understand that pumas would be significantly impacted by a reduction in their primary food source.

A further concern, which the two are currently researching, is the interplay between wildlife and humans. The national reserve increasingly sees visitors eager to witness big cats and foxes in their natural environment, while the sheep and cattle industries are increasingly using remote terrain for livestock cultivation.

"Pumas do occasionally kill livestock, which is a challenge we're looking into right now," said Kelly, an affiliate of Virginia Tech's Fralin Life Sciences Institute. "The government would like to preserve the puma, but there are competing challenges of what kind of threat they pose to livestock and what kind of threat cattle or sheep farming poses to them."

Understanding how two predatory species can come to coexist has the potential to provide conservationists and ecologists with better ideas for how humans and wild animals can share a landscape.

Controversial delisting of the US gray wolf

 

IMAGE: A GRAY WOLF; THE SPECIES WAS RECENTLY DELISTED AS RECOVERED UNDER THE ENDANGERED SPECIES ACT. view more 

CREDIT: MICHAEL LAROSA ON UNSPLASH

On 29 October 2020, the US Fish and Wildlife Service (USFWS) announced the "successful recovery" of the US gray wolf population, with US Secretary of the Interior Secretary David Bernhardt stating that the species had "exceeded all conservation goals for recovery." These claims have been rebutted by numerous experts, who argue that the delisting decision is premature. Writing in BioScience, independent ecologist Carlos Carroll and colleagues argue that the declarations of recovery should be based on a more ambitious definition of recovery than one requiring the existence of a single secure population. Instead, they propose a framework for the "conservation of adaptive potential," which builds on existing agency practice to enhance the effectiveness of the Act. The authors argue that such an approach is particularly crucial in light of climate change and other ongoing threats to species. On this episode of BioScience Talks, Dr. Carroll is joined by coauthors Adrian Treves, Bridgett vonHoldt, and Dan Rohlf to discuss the recent USFWS action as well as prospects for gray wolf conservation.