The largest bears in the world use small streams to fatten up on salmon

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It's a familiar scene to anyone who's watched footage of brown bears catching sockeye salmon in Alaska: They're standing knee-deep in a rushing river, usually near a waterfall, and grabbing passing fish with their paws or jaws.

But a new study published in the journal Conservation Letters reveals a different picture of how and when bears eat salmon. Most of these bears, also known as grizzlies, are dipping into small streams to capture their iconic prey.
Using a foraging model based on the Wood River basin in southwest Alaska, a study team led by Oregon State University determined that while small-stream habitats have only about 20% of the available salmon in the watershed, they provide 50% of bear consumption of salmon.
"This tells us that populations of sockeye salmon that spawn in little streams are disproportionately important to bears," said study lead author Jonny Armstrong, an ecologist at Oregon State University. "Bears profit from these small streams because they offer salmon at unique times of the season. To capitalize on plentiful salmon runs, bears need them to be spread across time."
Small streams typically have cold water, which leads to populations of salmon that spawn much earlier in the season when no other populations are available to predators such as bears.
These results have potential consequences for how environmental impact assessments are conducted and evaluated for large projects such as the proposed Pebble Mine in Alaska's Bristol Bay.
These reports typically focus on how the project will affect the abundance of salmon in lakes and rivers, but they usually overlook smaller habitats, Armstrong said.
"When people want to build a large mine, they think these streams don't matter because they represent a small fraction a watershed, in terms of area or salmon abundance. In conservation and management, we generally place value on the largest runs of salmon at the expense of the smallest ones," Armstrong said. "If we pose a different question and ask which habitats are important for the ecosystem, then small streams become particularly relevant."
The researchers developed a mathematical model that explores how watershed development and commercial fisheries affect how many sockeye salmon are available to grizzlies. The model simulated different patterns of development and explored how they affected the number of salmon bears consumed.
Protecting large salmon runs at the expense of smaller ones turned out to be bad for bears.
"This causes the bears' total salmon consumption to drop off faster compared to strategies that protected small salmon runs and the early feeding opportunities they offer to bears," Armstrong said. "If you impair these areas, you may only reduce the total number of salmon by a little, but the number of salmon that end up in bear's stomachs -- you could reduce that a lot."
According to the study authors, there are two significant reasons why the largest bears in the world are drawn to small streams to eat salmon.
First, the fish in these streams are easy to catch for adult and juvenile grizzlies. And second, because the water is colder than in lakes and rivers, salmon spawn in them earlier -- probably to give their eggs more time to incubate, the authors said. So, the fish are plentiful by the first week of July -- making them the first places bears fish after they emerge from hibernation.
"When they come out of hibernation, the bears are just scraping by and barely making it," Armstrong said. "Having these streams means they can start eating salmon in early July, which is about six weeks before the river- and lake-salmon populations start spawning and become available to bears. It's an incredible foraging opportunity for bears."
Armstrong added, "I'm sure that native Alaskans who subsisted on salmon were keenly aware of this, too."

Habitat restoration alone not enough to support threatened caribou

Other conservation methods may also be needed until restored sites are more established

University of British Columbia

IMAGE: New UBC research suggests restoring habitat may not be enough to save threatened woodland caribou--an iconic animal that's a major part of boreal forests in North America and a key... view more 

Credit: UBC Faculty of Forestry

New UBC research suggests restoring habitat may not be enough to save threatened woodland caribou--an iconic animal that's a major part of boreal forests in North America and a key part of the culture and economy of many Indigenous peoples in Canada.
Caribou populations have declined rapidly in recent decades across much of western Canada, including the oil sands region of northeastern Alberta. The researchers placed hidden cameras, known as "camera traps", in the area to see if replanting seismic lines has helped protect caribou by separating them from predators and fellow prey moving through the area.
Seismic lines, which are narrow strips of land cleared to make way for oil and gas exploration, are thought to disturb caribou habitat and promote faster travel for predators and food competitors. These lines do not recover quickly naturally, but are now being restored through replanting with native trees and natural features like mounds and tree debris.
"In theory, restoration should have made it much more difficult for predators to travel across the caribou range, but our cameras showed us a different picture," said lead author Erin Tattersall, who did the work as a master's student in forest sciences at UBC.
Predators like black bears and wolves, and prey like moose, used the restored seismic lines about as much as they used unrestored lines. Only white-tailed deer--a key caribou competitor --showed less use of the restored lines. Caribou preferred to use lines located in low-lying wetland areas, as well as more isolated lines--whether they'd been restored or not.
"In other words, restoration did not do much to keep caribou apart from their predators and competitors, at least not in the short term," Tattersall said.
The work, published last week in Biological Conservation, is one of the first to challenge the assumed impacts of a caribou recovery strategy, and researchers say it makes the case for more rigorous analysis of conservation methods.
"It's possible caribou will eventually recover in the area we studied, and other restoration approaches in other regions could also prove more immediately effective for caribou recovery," said senior author Cole Burton, a professor of forestry who leads the Wildlife Coexistence Lab at UBC. "But our results clearly show that we can't simply assume the best--it's necessary to closely monitor the actual results of restoration."
And while the study focuses on Alberta caribou, it can also be important for discussions on saving B.C. caribou, Burton added.
"We are seeing steep declines in many of B.C.'s caribou populations, and even total losses of some," he said. "Effective restoration of already degraded habitats will ultimately be critical to recovering our caribou."

What wolves' teeth reveal about their lives

IMAGE: Biologist Blaire Van Valkenburgh has spent more than three decades studying the skulls of large carnivores. Here she displays a replica of a saber-toothed cat skull. At left are the... view more 

Credit: Christelle Snow/UCLA

UCLA evolutionary biologist Blaire Van Valkenburgh has spent more than three decades studying the skulls of many species of large carnivores -- including wolves, lions and tigers -- that lived from 50,000 years ago to the present. She reports today in the journal eLife the answer to a puzzling question.
Essential to the survival of these carnivores is their teeth, which are used for securing their prey and chewing it, yet large numbers of these animals have broken teeth. Why is that, and what can we learn from it?
In the research, Van Valkenburgh reports a strong link between an increase in broken teeth and a decline in the amount of available food, as large carnivores work harder to catch dwindling numbers of prey, and eat more of it, down to the bones.
"Broken teeth cannot heal, so most of the time, carnivores are not going to chew on bones and risk breaking their teeth unless they have to," said Van Valkenburgh, a UCLA distinguished professor of ecology and evolutionary biology, who holds the Donald R. Dickey Chair in Vertebrate Biology.
For the new research, Van Valkenburgh studied the skulls of gray wolves -- 160 skulls of adult wolves housed in the Yellowstone Heritage and Research Center in Montana; 64 adult wolf skulls from Isle Royale National Park in Lake Superior that are housed at Michigan Technological University; and 94 skulls from Scandinavia, collected between 1998 and 2010, housed in the Swedish Royal Museum of Natural History in Stockholm. She compared these with the skulls of 223 wolves that died between 1874 and 1952, from Alaska, Texas, New Mexico, Idaho and Canada.
Yellowstone had no wolves, Van Valkenburgh said, between the 1920s and 1995, when 31 gray wolves were brought to the national park from British Columbia. About 100 wolves have lived in Yellowstone for more than a decade, she said.
In Yellowstone, more than 90% of the wolves' prey are elk. The ratio of elk to wolves has declined sharply, from more than 600-to-1 when wolves were brought back to the national park to about 100-to-1 more recently.
In the first 10 years after the reintroduction, the wolves did not break their teeth much and did not eat the elk completely, Van Valkenburgh reports. In the following 10 years, as the number of elk declined, the wolves ate more of the elk's body, and the number of broken teeth doubled, including the larger teeth wolves use when hunting and chewing.
The pattern was similar in the island park of Isle Royale. There, the wolves' prey are primarily adult moose, but moose numbers are low and their large size makes them difficult to capture and kill. Isle Royale wolves had high frequencies of broken and heavily worn teeth, reflecting the fact that they consumed about 90% of the bodies of the moose they killed.
Scandinavian wolves presented a different story. The ratio of moose to wolves is nearly 500-to-1 in Scandinavia and only 55-to-1 in Isle Royale, and, consistent with Van Valkenburgh's hypothesis, Scandinavian wolves consumed less of the moose they killed (about 70%) than Isle Royale wolves. Van Valkenburgh did not find many broken teeth among the Scandinavian wolves. "The wolves could find moose easily, not eat the bones, and move on," she said.
Van Valkenburgh believes her findings apply beyond gray wolves, which are well-studied, to other large carnivores, such as lions, tigers and bears.
Extremely high rates of broken teeth have been recorded for large carnivores -- such as lions, dire wolves and saber-toothed cats -- from the Pleistocene epoch, dating back tens of thousands of years, compared with their modern counterparts, Van Valkenburgh said. Rates of broken teeth from animals at the La Brea Tar Pits were two to four times higher than in modern animals, she and colleagues reported in the journal Science in the 1990s.
"Our new study suggests that the cause of this tooth fracture may have been more intense competition for food in the past than in present large carnivore communities," Van Valkenburgh said.
She and colleagues reported in 2015 that violent attacks by packs of some of the world's largest carnivores -- including lions much larger than those of today and saber-toothed cats -- went a long way toward shaping ecosystems during the Pleistocene.
In a 2016 article in the journal BioScience, Van Valkenburgh and more than 40 other wildlife experts wrote that preventing the extinction of lions, tigers, wolves, bears, elephants and the world's other largest mammals will require bold political action and financial commitments from nations worldwide.
Discussing the new study, she said, "We want to understand the factors that increase mortality in large carnivores that, in many cases, are near extinction. Getting good information on that is difficult. Studying tooth fracture is one way to do so, and can reveal changing levels of food stress in big carnivores."

Poo's clues: Moose droppings indicate Isle Royale ecosystem health

Michigan Technological University

IMAGE: An adult moose must eat approximately 40 pounds of vegetation per day just to keep itself going. Yet despite their need to consume large volumes of food every day, moose... view more 

Credit: Sarah Hoy/Michigan Tech

Given the choice between ice cream and vegetables, for many people it'll be the ice cream. But sometimes it depends on the situation. If you'd eaten ice cream every day for a week, you might prefer the salad. Human preferences for different foods often depend on what's common fare and what's rare.
For non-human animals, like moose, the situation is equally complicated. An adult moose must eat approximately 40 pounds of vegetation per day just to keep itself going. Yet despite their need to consume large volumes of food every day, moose do not eat everything they come across. Instead, moose are considerably more selective than is obvious when deciding which plant species to eat.
Sarah Hoy, assistant research professor, and John Vucetich, distinguished professor, in the School of Forest Resources and Environmental Science at Michigan Technological University, in collaboration with scientists from the United States Geological Survey (USGS) and the University of Wyoming, have developed a method to analyze why moose choose to eat what they do, how their choices change in the presence of predation and how moose diets actually affect the stability of entire ecosystems.
The results appear in "Negative frequency-dependent foraging behaviour in a generalist herbivore (Alces alces) and its stabilizing influence on food web dynamics" published in the Journal of Animal Ecology.
"The research shows how what you would think is a simple decision -- what to eat -- is a complex process that depends on many environmental factors, such as how common food types are, how likely a moose is to be killed by a predator and how difficult deep snow makes it to move around and find food," Hoy said. "The moose eat upwards of 40 pounds each day. You'd think if you had such dietary requirements you'd stuff your face with anything you can find, but that doesn't appear to be the case."
"Something one might consider small, even trivial -- what a moose chooses to eat -- appears to have a stabilizing effect on the whole food web." -- Sarah Hoy, assistant research professor
The advantage to moose of taking the time to seek out and eat plant species that are relatively rare is a well-balanced diet, which requires nutrients that might be found only in those rarer plants. Many plants also contain chemicals that are toxic to moose in large quantities, which means that moose can ingest them only in limited amounts. However, a moose whose palate is too discerning pays a price; a cost of focusing too much on the rare plants is the time spent on the search. Additionally, a moose in search of a delicacy might be a more likely target for a wolf.
"Moose have a choice: eat the rare stuff at risk of not eating enough food overall, or eat what is most common in the forest at risk of missing out on a well-balanced diet," Hoy said. "We hadn't really known how moose manage that choice until now."
Polarized Poop and Mathematics By analyzing a decade's worth of moose droppings under a polarized light microscope -- a technique known as microhistology, which is further explored on Michigan Tech's Unscripted science and research blog -- to determine what exactly moose are eating on Isle Royale, the researchers concluded that moose preferred to eat what was relatively rare in their home range. If balsam fir is rare, they prefer it; if balsam fir is common, they show less preference -- even passing it up in many cases to find a less common plant. However, moose appeared to become less fussy eaters in years when the risk of being killed by wolves was high and in years when deep snow likely made it more difficult for moose to move around and find food.
By combining the evidence of years of meticulous fieldwork with a mathematical model representing the Isle Royale system, Hoy and her fellow scientists were able to draw conclusions about why it's important that moose are choosy eaters in the context of the ecosystem.
Enter Rongsong Liu, associate professor of mathematics at the University of Wyoming. Liu built a mathematical food chain model that she said, "demonstrates that the selective foraging strategies of moose can have an important stabilizing effect on community dynamics and provide a useful framework for assessing the influence of the other aspects of foraging behavior on community stability."
The model further illuminates the strength of the connections across three trophic levels of the Isle Royale landscape: vegetation, herbivore, carnivore.
"The mathematical model is a way to test how important the patterns in moose behavior we observed are for the community as a whole," Hoy said. "Moose may change their diet in response to a harsh winter or a high risk of being killed by wolves, but how important is that to the ecosystem?"
Don DeAngelis, a research ecologist for the USGS, has worked with Liu to develop and analyze models of herbivores of the boreal forest, including moose. One factor influencing what a moose prefers to eat is the aforementioned toxins in certain plants and how those toxins can effectively skew moose diets toward better overall balance.
"The data implied the moose were deliberately limiting their intake of coniferous vegetation, and also that this effect was related to the level of other environmental conditions, probably the level of predation by wolves," DeAngelis said. "My role was to work with Liu to translate the way that we think wolves, moose and forest vegetation all interact with each other into mathematical equations, and then use these equations to build a model that reflects the way that the Isle Royale ecosystem works."
Ecological theory indicates that simple food chains, such as that of Isle Royale National Park, are prone to extinction. Where there is a single predator -- wolves -- and a single herbivore -- moose, which eats two basic kinds of plants: deciduous and conifer trees -- there can be erratic population fluxes. However, Hoy, Vucetich and colleagues discovered that the foraging behavior of the moose might be one factor that favors the persistence of wolves, moose and the different tree species in the food chain.
This distinctive combination of theoretical models and field observations from the predator-prey study on Isle Royale provides ecologists with more insight about how and why populations tend to persist where basic theories of ecology otherwise suggest that they should not.

Fearing cougars more than wolves, Yellowstone elk manage threats from both predators

IMAGE: Wolves are often implicated as the top predator affecting prey populations. New research from Utah State University indicates that cougars are actually the main predator influencing the movement of elk... view more 

Credit: National Park Service

Wolves are charismatic, conspicuous, and easy to single out as the top predator affecting populations of elk, deer, and other prey animals. However, a new study has found that the secretive cougar is actually the main predator influencing the movement of elk across the winter range of northern Yellowstone National Park.
The study highlights that where prey live with more than one predator species, attention to one predator that ignores the role of another may lead to misunderstandings about the impact of predators on prey populations and ecosystems. It also offers new insight into how prey can use differences in hunting behavior among predators to maintain safety from all predators simultaneously.
Utah State University researchers Michel Kohl and Dan MacNulty co-led the study, published in Ecology Letters, with Toni Ruth (Hornocker Wildlife Institute and Wildlife Conservation Society), Matt Metz (University of Montana), Dan Stahler, Doug Smith, and P.J. White (Yellowstone National Park). Their work was supported, in part, by the National Science Foundation, Ford Foundation, and Utah State University as part of Kohl's doctoral research. The study was based on long-term data from the Park's wolf and elk monitoring programs and Ruth's cougar research, which is detailed in a forthcoming book from the University Press of Colorado.
The team revisited global positioning system (GPS) data from 27 radio-collared elk that had been collected in 2001-2004 when numbers of wolves and cougars were highest. Kohl and MacNulty combined the elk GPS data with information on the daily activity patterns of GPS-collared cougars and wolves and the locations of cougar- and wolf-killed elk to test if elk avoided these predators by selecting for 'vacant hunting domains', places and times where and when neither predator was likely to kill elk.
"Cougars hunted mainly in forested, rugged areas at night, whereas wolves hunted mainly in grassy, flat areas during morning and at dusk" said Kohl, lead author of the paper and now an assistant professor at the Warnell School of Forestry and Natural Resources at the University of Georgia in Athens. "Elk sidestepped both cougars and wolves by selecting for areas outside these high-risk domains, namely forested, rugged areas during daylight when cougars were resting, and grassy, flat areas at night when wolves were snoozing".
Recognizing that cougars and wolves hunted in different places and at different times allowed the researchers to see how elk could simultaneously minimize threats from both predators. "Had we ignored the fact that these predators were on different schedules, we would have concluded, incorrectly, that avoiding one predator necessarily increased exposure to the other," said MacNulty, who is an associate professor in USU's Department of Wildland Resources and Ecology Center. "Movement out of the grassy, flat areas and into the forested, rugged areas to avoid wolves did not result in greater risk from cougars and vice versa because these predators were active at different times of the day".
Despite the compatibility of elk spatial responses to cougars and wolves, Ruth, who is now executive director of the Salmon Valley Stewardship in Salmon, Idaho, cautioned that "some adult elk still end up on the cougar and wolf menu, with those in poor condition during winter being most at risk".
Nevertheless, "the findings help explain why we observe wolves, cougars, and elk all coexisting and thriving on the Yellowstone landscape" said Stahler, who leads the current study of cougars in the Park. He notes that the ability of elk to coexist with wolves and cougars is consistent with their "long, shared evolutionary history".
More surprising, however, was that cougars, not wolves, exerted the most pressure on elk habitat selection. "Wolves are often the presumed or blamed predator for any change in a prey population, numerical or behavioral," said Smith, who leads the Park's wolf program. "Our research shows that this is not necessarily true, and that other large predators in addition to wolves need to be considered."
"Despite the fact that most prey species live in habitats with multiple predators, the majority of research on predator-prey interactions focuses on a single predator species," added Betsy von Holle, program director for the National Science Foundation's Division of Environmental Biology. "The novelty of this research is the simultaneous study of multiple predator species, revealing the complexity of predator avoidance behavior by the prey."

What drives Yellowstone's massive elk migrations?

Study finds elk have the means to adapt to changing climate cues, but migratory shifts may have unknown ripple effects throughout the region

University of California - Berkeley

IMAGE: Yellowstone's migrating elk use climate cues, like melting snow and greening grasses, to decide when to make the trek from their winter ranges in prairies and valleys to their summer... view more 

Credit: Joe Riis

Every spring, tens of thousands of elk follow a wave of green growth up onto the high plateaus in and around Yellowstone and Grand Teton national parks, where they spend the summer calving and fattening on fresh grass. And every fall, the massive herds migrate back down into the surrounding valleys and plains, where lower elevations provide respite from harsh winters.
These migratory elk rely primarily on environmental cues, including a retreating snowline and the greening grasses of spring, to decide when to make these yearly journeys, shows a new study led by University of California, Berkeley, researchers. The study combined GPS tracking data from more than 400 animals in nine major Yellowstone elk populations with satellite imagery to create a comprehensive model of what drives these animals to move.
"We found that the immediate environment is a very effective predictor of when migration occurs," said Gregory Rickbeil, who conducted the analysis as a postdoctoral researcher in Arthur Middleton's lab at UC Berkeley. This is in contrast with some other species, such as migratory birds, which rely on changing day length to decide when to move, Rickbeil pointed out.
The results, published in the current issue of the journal Global Change Biology, suggest that, as climate change reshapes the weather and environment of the park, elk should have the means to adjust their migratory patterns to match the new conditions.
While this adaptability may benefit the survival of the elk, it may also have unknown ripple effects in local economies and throughout the Greater Yellowstone Ecosystem -- one of the last remaining large, nearly intact ecosystems in Earth's northern temperate zone, which encompasses about 18 million acres of land managed by more than 25 public entities and hundreds of private landowners. Another recent UC Berkeley-led study suggests that climate change is likely to hit National Parks harder than other areas of the country.
"The decisions that these animals make about when to migrate are absolutely dependent on changes in the landscape, changes that are ultimately governed by the climate," said Middleton, an assistant professor of environmental science, policy and management at UC Berkeley and senior author on the study. "And in the future, with climate change, we should expect the timing of these mass movements to be altered, which will affect the other wildlife and the people who depend on them, including predators, scavengers and hunters across the ecosystem."
Though the migration study's period was too short to say whether or not climate change is already affecting migratory timing, the tracking data did reveal a surprising trend: Elk on average arrived on their winter ranges 50 days later in 2015 than in 2001. This change had been noted by wildlife managers in the area, but had yet to be quantified on the ecosystem scale until now.
"This [study] provides great insight into the adaptation strategies of elk to climate change in the Greater Yellowstone Ecosystem," said Jonathan Jarvis, former director of the National Park Service, who now serves as executive director of the Institute for Parks, People, and Biodiversity at UC Berkeley.
Jarvis noted that more broadly, the new picture of the Yellowstone elk migrations provided by the study's comprehensive mapping effort "clearly demonstrate the need to think and operate at the landscape scale." He added, "For the park managers, this kind of research gives them options and incentives, such as protection of migration corridors and seasonal habitats, for ensuring elk and other keystone species in the Greater Yellowstone Ecosystem will persist."
Eating and being eaten
Yellowstone's approximately 20,000 migratory elk are among the most important large mammals in the ecosystem, comprising about 10 million or so pounds of animal biomass pulsing in and out of the parks and adjacent wilderness areas each year -- so where they can be found at any given time matters to both animals and humans alike.
"These elk eat a lot of things, and they are eaten by a lot of things, so wherever these masses of hundreds or thousands of elk are on the landscape determines who gets to eat and who doesn't," Middleton said. "In some cases, this could be sensitive populations of carnivores, like grizzly bears or wolves, and on the human side, it could be hunters, some of whom are making their income as outfitters and guides."
Recent studies have shown that threatened grizzly bears depend heavily on newborn elk calves as a food source in spring -- right when the migration is happening -- and that a Yellowstone wolf kills, on average, 16 elk per year. Meanwhile, each fall, thousands of hunters from around the country pay guides for the chance to harvest an elk in the wilderness near Yellowstone.
While a smattering of studies has investigated the migration of individual herds in the park, none before this study had investigated the phenomenon on an ecosystem scale. To get a more complete picture of migration, Middleton partnered with state and federal wildlife managers in the Yellowstone region to pool information on 414 elk across nine herds that had been fitted with GPS collars between 2001 and 2017.
Rickbeil then analyzed the data to pinpoint when each elk made its trek from winter range to summer range and back again and used satellite images to infer the conditions on the ground during journeys.
He found that elk tended to leave their winter ranges and set out to their summer ranges as soon as the snow had melted and during the "green-up," when fresh, nutritious plant growth began to sprout. Likewise, encroaching snowfall and hunting pressure cued them to make the return journey.
The team was surprised by the extent of the elks' flexibility: One year, a female elk might migrate in early May, but the next year in late July, depending on the timing of snowmelt and green-up.
"They've got a big brain and big eyes, and they can look around and, to a large degree, see changes on the landscape and react to them," Middleton said.
However, Rickbeil notes, the snow cover and vegetation couldn't fully explain why the elk are now arriving so much later at their winter ranges. Variations in snow depth, which cannot be inferred from satellite data, might explain part of the dramatic change, Rickbeil said.
Alyson Courtemanch, who manages the Greater Yellowstone Ecosystem's Jackson elk herd as part of her job as a wildlife biologist with the Wyoming Game and Fish Department, says knowing the whereabouts of the elk is critical to her job setting hunting seasons and managing the spread of diseases among wild elk and domestic cattle.
"We've been observing a lot of really interesting changes over the past decade about the way that elk are moving across the landscape, specifically of the timing of the migrations," said Courtemanch, who supplied GPS data on the Jackson herd for the study. "This analysis helped confirm a lot of things that people on the ground had suspected were happening, but that weren't really quantified."
"It seems like these animals can adapt to changing climates, which is likely a good thing," Rickbeil said. "But there will be a lot of consequences to these changes."

Surprisingly, inbred isle royale wolves dwindle because of fewer harmful genes

Genomic signatures of extensive inbreeding in Isle Royale wolves, a population on the threshold of extinction

American Association for the Advancement of Science

The tiny, isolated gray wolf population on Isle Royale has withered to near-extinction, but not because each animal carries a large number of harmful genes, according to a new genetic analysis. Instead, each one has been more likely to inherit the same harmful recessive alleles from both parents. This pattern enables expression of related genes as physical deformities, including the population's characteristically crooked spines. The findings contradict many previous studies, which suggest the crux of the genetic problem for historically small or sharply reduced populations is an increase in the quantity of harmful alleles. While the Isle Royale wolf population once consisted of 50 wolves, it has dwindled to just two - a father and daughter that are also half siblings. The collapse of the Isle Royale wolf population occurred despite a reported genetic "rescue" in 1997 by a single migrant from the mainland. To better characterize the genome-wide effects of intense inbreeding and isolation on this population, and their role in its decline, Jacqueline A. Robinson and colleagues analyzed mutations within the protein-coding regions of DNA from Isle Royale wolves, compared with genetic data from wolves in nearby mainland Minnesota. The former didn't have a greater number of deleterious genes than the Minnesota group, but the proportion of Isle Royale wolves with paired harmful recessive alleles in their genome was 38.4% higher. When the researchers compared Isle Royale genetic data with that from other wolf genomes from around the world, they found that individuals from historically large populations more frequently contained two different alleles at a gene location, while those from historically small populations more frequently contained short sequences of identical allele pairings, as with the Isle Royale wolves. These findings, supported by further simulations, contain broader implications for conservation efforts to manage fragmented populations at risk for decline due to inbreeding. Individuals brought in from historically small populations, rather than those from larger, more diverse gene pools, may actually prove more beneficial because they carry fewer potentially harmful alleles.

Wolf-dog 'swarms' threaten Europe's wolves

"Swarms" of wolf-dog crossbreeds could drive Europe's wolves out of existence, according to the lead author of new research.
Such hybridisation - driven by human activities that destroy habitats and mean wolves encounter more and more free-roaming dogs - threatens the "genetic identity" of wolves.
The study compares the views of more than 40 scientists and warns that a lack of engagement and agreement could hamper efforts to tackle wolf-dog hybridisation.
The findings suggest most scientists agree on the nature of the problem, but are divided on how to deal with it.
"We need to address this issue before wolf-dog hybrids backcross with wolves to the extent that wolf populations will be lost to hybrid swarms, and the conservation of wild populations will become unfeasible," said lead author Valerio Donfrancesco, of the Centre for Ecology and Conservation on the University of Exeter's Penryn Campus in Cornwall.
"In this paper, we argue that scientific agreement is crucial to encourage decision-makers to act, and to raise awareness about this conservation issue in society at large.
"The fact that we know so little about the ecology, behaviour and social acceptance of the wolf-dog hybrids adds a layer of concern to the issue."
The study, which allowed scientists to share their views anonymously, revealed agreement that people should be educated about the impact of free-roaming dogs, and that governments should remove wolf-dog hybrids from small and recovering wild wolf populations.
But scientists were divided on issues such as how to remove hybrids and free-roaming dogs, and whether they should be kept captive, sterilised and released or killed.
Donfrancesco said: "The disagreements emerged from diverging ethical values between scientists of different backgrounds, such as ecologists and geneticists, from the lack of data on the effectiveness of different interventions, and from the worry of some scientists that on practical grounds allowing the removal of hybrids would open a legal loophole for the killing of wolves."
Co-author Paolo Ciucci, of the Sapienza University of Rome, said: "The management of hybrids and wolf-dog hybridisation should not be a taboo topic, especially within the scientific community.
"There are margins to develop further consensus among scientists if further research addresses topical issues such as the effectiveness and the feasibility of control measures and their social acceptability.
"Scientists should not avoid the problem just because its management appears overly complex."
Co-author Dr Nibedita Mukherjee, from the University of Exeter, added: "We hope that by highlighting areas of disagreement and why they occur, we will be able to build a more unified scientific opinion, and aid an effective management of this urgent issue."
An estimated 17,000 wolves live in Europe, in populations of varying sizes in countries as far apart as Spain, Greece and Finland.
The paper, published in the journal Frontiers in Ecology and Evolution, is entitled: "Unravelling the scientific debate on how to address wolf-dog hybridization in Europe."

The return of the wolves

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Date:

May 20, 2019

Source:

University of Freiburg

Summary:

Researchers examine global strategies for dealing with predators.

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FULL STORY

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Howling wolves.

Credit: © dine Haase / Adobe Stock

The current return of wolves to human-dominated landscapes poses a major challenge for the protection of this species, says conservation biologist and private lecturer (PD) Dr. Marco Heurich from the University of Freiburg. He emphasizes that conflicts arise around the conservation of wolves in these landscapes due to farm animal slaughter, competition with hunters and human protection. The question of how humans can coexist with predators triggers a strong emotional debate.

Based on these observations, a team of scientists led by Dr. Dries Kuijper from the Mammal Research Institute of the Polish Academy of Sciences in Białowieża, Poland, analyzed the existing knowledge on how to deal with large carnivores living in the wild in Europe and other parts of the world. The aim was to enable an objective, scientifically sound discussion of various scenarios of wolf management. The researchers have presented their results in the current issue of the scientific journal Biological Conservation.
According to the scientists, the control of wolf populations, which is often advocated in other countries outside the European Union, is in clear contradiction to current European legislation. In addition, several studies show that control of populations by hunting does not resolve conflicts and can even lead to problems between humans and animals. Fencing in the areas where wolves live is a common tool in other parts of the world for the containment of predators. But even that, according to the researchers, is not practicable in the highly fragmented European landscapes to the extent necessary to maintain a healthy wolf population. In addition, large-scale fencing has a negative impact on other wildlife, leading to fragmentation of habitats. However, the scientists claim smaller electric fences are effective in excluding wolves from high-conflict areas with a high density of livestock.
From a legal standpoint, the least problematic situation is when no preventive measures are taken against the wolves, but farm animals are protected and compensation is paid for any damage caused. The team around Heurich assumes, however, that the conflicts between humans and wolves will become more frequent as wolf populations grow. In addition to protecting farm animals with electric fences or guard dogs, for example, the researchers recommend strengthening the natural population of ungulates such as deer and red deer in order to prevent conflicts.
In addition, the scientists suggest influencing wolf behavior and working towards proper human behavior. The use of so-called deterrence measures, i.e. negative conditioning, is intended to ensure that animals avoid humans. At the same time, however, people must learn to have respect for animals. In this way a meeting of wolves with farm animals and humans can be avoided. However, the Freiburg scientists explain that so far the only experience gathered for this method stems from the Yellowstone National Park in the US, so that its suitability for Central Europe must first be investigated.
Finally, Heurich and his colleagues stress that an important aspect of wolf management is to provide the public with a balanced view of the wolves: "People must be convinced of the ecological value that the return of the wolves has. It is necessary to show that these animals pose a very low risk to human safety. However, we must not forget that wolves are large predators who demand respect."

Isle Royale winter study: 13 new wolves, 20 radio-collared moose

IMAGE: Two of the newly introduced gray wolves pick their way through deep snow on Isle Royale. view more 

Credit: Rolf Peterson/Michigan Tech

Fifteen wolves. 2,060 moose. Extensive ice and deep, powdery snow. Michigan Tech researchers have released the annual Winter Study report. In its 61st year, the study is the longest running examination of a predator-prey relationship in the world.
The report chronicles the four-week research expedition to the island, where researchers track -- by ski and plane -- wolves and moose, collar moose, and catalogue the cascading effects of an ecosystem that has lacked a healthy population of apex predators for a number of a years.
New Tracks in the Snow Prior to this fall and winter's wolf reintroductions, the wolf population on the remote island had remained at just two -- a strongly bonded, but also highly inbred male-female pair -- for three years. The moose population, lacking predation, expanded by an average of 19% each year during the past eight years since 2011, when the wolf population first dwindled to fewer than 10 individuals. Consequently, primary plant species in moose diets -- balsam fir and watershield -- dropped precipitously.
The National Park Service (NPS), after an extensive review process, decided to introduce new wolves to the island. In September and October 2018, NPS introduced four Minnesota-born wolves (one male and three females) to the island. In late October, the male wolf died and on January 31, 2019, one of the female wolves left the island by crossing the ice bridge that had formed on Lake Superior, which reached nearly 95% ice cover.
In late February, NPS in collaboration with the Ontario Ministry of Natural Resources (OMNRF), introduced four Canadian-born wolves, including a male and female from a pack near Wawa, Ontario, and two males from Michipicoten Island, Ontario. In late March, NPS and OMNRF introduced seven more wolves to the island, including three males and three females from Michipicoten and one male from near Wawa.
For researchers, perhaps equal parts vexing and exciting are the unanswered questions about the future of the wolves on the island.
"Some of the most important questions at this point are: Will there be pups this year? How quickly will the wolves form a pack, and how many packs?" said John Vucetich, professor of ecology at Michigan Tech and report co-author. "As is so often the case with nature, the answer is, nobody knows -- but three packs is the likely answer."
The Michigan Tech School of Forest Resources and Environmental Science researchers speculated that wolf pups could be possible this year, but the new wolves were introduced to the island near the end of the traditional breeding season, so only time will tell.
Vucetich added that there are similar questions pertaining to the moose. "What's going to happen to the moose population? Will it keep increasing from 2,060, or level off, or decline quickly or slowly? The answer is the same, nobody knows."
To seek the answers, researchers fitted the first GPS-enabled radio collars since 1985 to the newly introduced wolves and 20 moose. The collaring efforts are part of a collaboration with University of Minnesota College of Veterinary Medicine, National Park Service and Grand Portage Band of Lake Superior Chippewa.
New Collars, More Data Collaring the moose will also help researchers understand the effects of predation, as well as other factors that influence the moose population, including forage abundance, parasites and climate.
"As soon as you start collaring individuals you learn about them in great detail; they all have interesting stories," said Rolf Peterson.
The researchers are also excited about their collaboration with Jennifer Forbey, an associate professor of biology at Boise State University, who studies the chemical ecology of herbivory.
Scientists are coming to understand that the reason many herbivores eat what they eat is due to subtle chemical differences in the plants. Isle Royale offers a unique environment in which to study herbivory.
"Most people study a herbivore's decision of what to eat when there are no predators involved," Vucetich said. "They've got all day to figure out which plant they want. But when exposed to a predator, they still have a choice of which plant to eat, but the calculus of the decision is more complex."
And what individual moose elect to eat may have a profound impact on their population as a whole. Lacking predators, the growing moose population has ravaged much of the available forage on the island, and that has consequences.
"We expect there might be a slowing down of moose population growth next year, at least at the west end of the island," said Sarah Hoy, assistant research professor. "The moose have severely damaged much of the vegetation they rely on during winter on the western end of the island. And it was such a deep-snow winter, it'll have been more difficult for them to get around and find food."
According to the report, moose browsing is one factor relating to a decline in the number of mature fir trees. In 1988, 473 mature balsam fir trees were tagged on the western end of the island. Only 28 (6%) of those tagged trees remained in 2018.
Watershield, a floating-leafed aquatic plant, has also experienced decline as the moose population grew. In the late 2000s, watershield covered as much as 90% of the water surface in ponds on the eastern side of the island. By 2018, it was not readily found in aquatic areas.
Next Steps
Reintroducing a thriving wolf population to Isle Royale also has an effect on the island's other residents, which include beavers and foxes. Wolves eat beavers as well as moose, and so the beaver population, which has been booming since 2012, may eventually decline to levels of a decade ago, about 20% of current numbers. Foxes, which are scavengers, will likely benefit from the return of the island's apex predator.
Also of interest to the scientists is evidence of yet additional wolves who may have crossed the ice bridge and visited Isle Royale during the winter. Each winter, the Isle Royale wolf-moose project embeds a husband-wife team, Ky Koitzsch and Lisa Osborn, to observe the moose and wolves by skis, and they found evidence of the tracks of an unknown wolf on the island. Aerial survey suggested that perhaps three wolves crossed the ice and circumnavigated the island, but this may have been just a quick visit followed by a return home to the mainland.
Peterson, Hoy and Vucetich are headed back to the island in May to conduct summer research, along with six students who will showcase their progress on the project's social media.
As usual, four to five dozen volunteers will head to the island for the annual Moosewatch Expedition to collect bones at locations where the collared wolves seem to have lingered long enough to presume they were feeding on a dead moose.
"When we're there in the winter, we learn a tremendous amount about the moose population, but this summer we are hoping to learn a lot more detailed information about moose behavior and what they like to eat, depending on how tolerant the collared moose are of being watched," Peterson said. "This summer should likewise prove valuable in determining the trajectory of both wolf and moose populations. This is definitely a notable year."
Indeed, there is a sense of renewal in this year's report. For the first time in 10 years, the researchers spotted fresh wolf tracks at Windigo.

New study questions effects of reintroducing top predators

University of Wyoming

IMAGE: Wolves face off with cow elk in the Lamar Valley of Yellowstone National Park. While wolf reintroduction in the mid-1990s resulted in a drop in Yellowstone elk numbers, it didn't... view more 

Credit: Daniel Stahler

For years, scientists have assumed that when top predators are reintroduced to an ecosystem, the effects are predictable: The ecosystem will return to how it was before the predators were wiped out.
Now, University of Wyoming researchers have published a study showing that there's little evidence for such claims. This has big implications for wildlife conservation in places such as Yellowstone National Park.
Most people are probably familiar with the story of Yellowstone's wolves. Wolves were wiped out in Yellowstone in the 1920s and, in their absence, elk became much more common and ate so much vegetation that it degraded the ecosystem.
Wolves were reintroduced to Yellowstone in the mid-1990s and over the next two decades brought profound change to the ecosystem. The number of elk decreased, while the number of aspen, willow and cottonwoods increased. Biologists observed positive responses by other animals, from songbirds to beavers. Scientists assumed that Yellowstone's ecosystem is on its way to being restored to historical conditions.
But this new study questions that assumption: Do we really know what those historical conditions were? And, does reintroducing apex predators alter ecosystems with any predictability at all?
The team of researchers from UW, Yale University and the University of British Columbia-Okanagan set out to find the answer. The results were published in the journal Biological Conservation earlier this week.
Ecosystem restoration via large carnivore reintroduction relies on two critical assumptions. First, large carnivore reintroduction has to initiate a predictable trophic cascade -- that is, where carnivores reduce the abundance of herbivores, which, in turn, increases the abundance of the plants they feed on. Second, the magnitude of that trophic cascade has to push an ecosystem back to a previous state.
But lots of other things can happen, too. Reintroduction of large carnivores might not affect the ecosystem much at all. Or the ecosystem might veer off in a new, unpredictable direction due to changes to the ecosystem or biological communities that occurred when large carnivores were absent. This is particularly likely in today's era of climate change and invasive species, the researchers say.
There aren't many studies on this topic, so the researchers collected studies that included data on the reintroduction of native apex predators or removal of invasive ones. These events are two sides of the same coin: Reintroductions and removals should work the same way, but in opposite directions.
They found that trophic cascades brought on by these events don't appear to be predictable -- sometimes you get them, sometimes you don't. In fact, they found only one consistent result: When invasive apex predators were removed, smaller predators such as coyotes, foxes and rats become more common.
Jesse Alston, the lead author on this study, says there are two take-home messages to this work.
"We need more studies," he says. "More tests of this 'assumption of reciprocity,' as we call it -- particularly via rigorous experimental studies -- would be really helpful. This is hard data to get, but we really do need it before we can credibly claim that large carnivores restore ecosystems. They might not."
"We also think that large carnivore reintroduction should be pursued for its own sake," Alston adds. "Large carnivores are great, but using their effects on ecosystems to justify reintroduction might not hold up to scrutiny and could be counterproductive in the long term.
"We hope we set up a nice framework for thinking about large carnivore introduction and invasive species removal that others can run with. We want to raise an important question, but it's going to take lots of folks to provide a definitive answer. This is an unfinished story."

Yellowstone elk don't budge for wolves

S.J. & Jessie E. Quinney College of Natural Resources, Utah State University

IMAGE: Utah State University researchers and their colleagues have shown that wolves reintroduced to Yellowstone National Park in the mid-1990s have negligible impacts on the movements of adult female elk that... view more 

Credit: Matt Metz

Elk roam the winter range that straddles the northern boundary of Yellowstone National Park with little regard for wolves, according to a new study illustrating how elk can tolerate living in close proximity to the large predator.
The study offers new insight into how wolves can have negligible impacts on elk movements, and how elk may simply ignore the risk of wolf predation while navigating the landscape in search of forage. It also adds to a growing body of evidence that changes in elk distribution and vegetation conditions in northern Yellowstone since wolf reintroduction in the mid-1990s are not caused by wolves altering elk movement behavior.
Utah State University researchers Dan MacNulty and Michel Kohl co-led the study, published in the Journal of Animal Ecology, with Jeremy Cusack (University of Stirling), Tim Coulson (University of Oxford), Matt Metz (University of Montana), Doug Smith and Dan Stahler (Yellowstone National Park). Several organizations funded the research, including the National Science Foundation, Natural Environment Research Council, Yellowstone Forever, The Tapeats Fund, Perkins-Prothro Foundation, and the National Park Service. The Park-led wolf and elk monitoring programs provided data for the project.
The team used global positioning system (GPS) radio-collars to track the movements of elk and wolves across four winters between 2012 and 2016. They tracked 34 adult female elk and at least one member of each dominant wolf pack. The collars recorded the location of the animals every 1-3 hours, providing comprehensive data on how they used the landscape. The team tested if elk avoided wolves that were in close proximity, and if elk avoided 'risky areas' where they might be killed by wolves, including where wolf densities were high; where wolves had previously killed elk; and open grasslands where wolves often hunted.
"We compared recorded elk movements with those from a simulation that described how elk would move if they completely ignored wolves and risky areas" says MacNulty, who has studied wolf-elk interactions in northern Yellowstone since 1995 and is an associate professor in USU's Department of Wildland Resources and Ecology Center. "In 90% of cases, there was no difference between real and simulated elk movements, indicating that our sample of real elk mostly ignored the risk of wolf predation".
According to Cusack, the lead author of the study, most elk did not alter the location and configuration of their annual winter home ranges to minimize overlap with wolves and risky areas, and none bothered to steer around wolves that were in the immediate vicinity. "A few elk avoided open grasslands during daylight hours when wolves were most active, which mirrors the result of a separate recent study that examined finer-scale elk movements in the early 2000s when wolves and elk were more numerous," explained Cusack.
The findings are also in line with other studies of northern Yellowstone elk, including one that compared elk movements before and after wolf reintroduction and found that "in winter, elk did not spatially separate themselves from wolves". Another study reported that "elk did not grossly modify their migration timing, routes, or use areas after wolf restoration".
Why don't elk budge for wolves? "A main reason is that elk tend to be philopatric, which means they have an inherent tendency to habitually return to the same wintering and summering areas year after year," says MacNulty. "Familiarity with an area helps them find the high quality forage they need, and this outweighs the small chance they encounter and fall prey to wolves."
MacNulty and Cusack estimated that elk in their study encountered wolves once every 7 to 11 days, and previous research found that elk frequently survive their encounters with wolves. Low risk of predation was also reflected in relatively high rates of annual survival, particularly among younger adults. "Elk in their prime do not have a massive incentive to avoid wolves, especially in winter when forage is scarce," explains MacNulty.
He says that elk intransigence towards wolves is a reminder that altered movement behavior is not the only way prey species avoid predation.
"Antipredator behaviors during encounters - including fighting back, grouping, and running - are effective ways for large-bodied, philopatric prey like elk to avoid predation without abandoning or reconfiguring their home ranges," he says.
"This has implications for understanding how wolves and other predators, including humans, affect the distribution of philopatric prey like elk. Predators removing different numbers of elk in different areas is the main way they affect elk distribution. Elk movement away from risky areas, if it happens, is secondary."

Coyotes are not controlling deer populations in eastern US states

Coyotes expanded their range to colonize eastern North America over the last century, where their impacts on white-tailed deer populations are highly debated. In a Journal of Wildlife Management study, researchers conducted the first long-term, large scale assessment and documented no consistent decline in deer harvest numbers after coyote arrival.
For the study, the team evaluated deer harvest numbers from 1980 to 2014 in 384 counties of six eastern US states.
The results indicate that coyotes are not limiting deer numbers and that coyote removal programs will do little to increase regional deer numbers.
"Coyotes on the east coast of the United States have not been limiting deer, so eradicating coyotes is not an efficient way to increase deer numbers in the region," said lead author Dr. Eugenia Bragina, of the Wildlife Conservation Society.

Video on this:  

IMAGE: A coyote captured on camera trap preying on a deer fawn. view more 

Credit: Dr. Aimee P. Rockhill (Western Carolina University) and Dr. Christopher S. DePerno (North Carolina State University)

Coyotes eat deer, but not enough to limit the deer population at a large scale. A new study of deer numbers across the eastern United States has found that the arrival and establishment of coyote predators has not caused the number of deer harvested by hunters to decline.
A video presenting this research is available for article embedding or linking here: https://youtu.be/2XCbHhDlU_k
"With wolves and cougars extinct in most of the eastern U.S., white-tailed deer have become abundant, sometimes overabundant," says Roland Kays, wildlife biologist at the North Carolina Museum of Natural Sciences and North Carolina State University, and co-author of a paper describing this research. "Coyotes moved in as the new top predator of the east, but they aren't nearly as effective deer hunters as wolves, so there's been a lot of controversy about whether these medium-sized predators can really limit deer populations at large scales."
Previous studies of how coyotes might be affecting deer populations have produced inconsistent results. Some experimental removals of coyotes found that fawn survival increases following coyote removal, but others have shown no effect. Kays and a team of researchers led by Eugenia Bragina from NC State, surveyed deer population trends from 1981 to 2014 using data from 384 counties across six eastern states. "Our study is unique because it's the first to link coyote presence to changes in deer population at a large scale," Bragina says. "Getting the big-picture of the interactions between these species helps inform the management practices of these species by hunting agencies."
The researchers collected county-by-county data on coyote arrival by assessing museum collections, and deer population numbers by tracking hunting records from state wildlife agencies. They evaluated these data for changes in the number of deer harvested after coyote arrival and establishment in an area, while accounting for environmental differences like climate and landscape. They found that the number of harvested deer in all states generally increased over time, and that there was no consistent crash in harvest numbers following coyote arrival. They concluded that coyotes are not controlling deer populations at a large region-wide scale in the eastern North America.
"We see direct evidence of coyote predation on deer when looking at coyote scat or even spotting them with camera traps carrying off deer fawns," says Chris Deperno, a co-author on the study from NC State. "Though coyotes are known to kill adult deer, predation is focused primarily on vulnerable individuals that are sick, injured or in late stage pregnancy. Predation of healthy adults is uncommon."
The researchers caution that this species interaction could potentially change as coyote numbers are still on the rise across the eastern U.S. It is unknown whether coyote populations will increase in number or density enough to influence deer populations in the future. Human-induced changes in habitat quality or landcover may also influence how these species interact.
Management efforts to increase deer population sizes involving coyote removal, the researchers advised, are unlikely to be effective at large scales or over long periods of time. "Coyote removal as a method of increasing deer abundance is expensive and labor-intensive," Bragina says. "We hope that this research leads to more acceptance of this carnivore by people. Coyotes are here to stay."
The paper, "No region-wide effects on white-tailed deer following eastern coyote colonization," is published in the Journal of Wildlife Management and Wildlife Monographs. Allison Hody, Christopher Moorman and Christopher Deperno from NC State, as well as L. Scott Mills from University of Montana, co-authored the research.

Hungry moose more tolerant of wolves' presence

IMAGE: A GPS-collared moose in western Wyoming moves into its desired habitat. New University of Wyoming research has documented interactions between moose and wolves in the region. view more 

Credit: Mark Gocke

Driven by the need for food, moose in western Wyoming are less likely to change their behavior to avoid wolves as winter progresses, according to new research by University of Wyoming scientists.
The findings, published today (March 13) in the journal Ecology, provide new insights into the interactions of the region's apex predators and their prey. The results also highlight the complexity of the relationships between wolves and big-game species, making it difficult to reach general conclusions about whether and how fear of wolves has impacted the ecosystem, the researchers say.

"We have known for some time that hungry animals will tolerate the presence of predators in order to forage and avoid starvation, and that phenomenon, called the 'starvation-predation hypothesis,' is supported by our research," says Brendan Oates, now with the Idaho Department of Fish and Game, who conducted the research as a UW graduate student. "In this case, close proximity of wolves does cause moose to move, but not enough to drive them from their preferred habitats -- especially late in the winter."

Oates is the lead author of the Ecology paper. Co-authors include his UW advisers: Jake Goheen, associate professor in UW's Department of Zoology and Physiology, and Matt Kauffman, a U.S. Geological Survey researcher based at UW. UW's Jerod Merkle, assistant professor in the Department of Zoology and Physiology, also was involved with the research, as were agency personnel from the National Park Service and U.S. Fish and Wildlife Service.

The scientists tracked movements of dozens of GPS-collared moose and wolves in Grand Teton National Park and the Bridger-Teton National Forest over a five-year period, detecting 120 unique encounters among 25 individual moose and six wolf packs. An encounter was defined as when moose and wolves were within about 1,600 yards of each other.

They found that movements of moose increased in early winter following encounters with wolves, but only when wolves were within about 550 yards. Even then, the moose didn't move from their preferred habitat, which is near streams and marshy areas. Late in the winter, when the moose were presumed to be hungrier, there was no change in the movement rates of the animals in response to wolves in the vicinity.

"The unwillingness of moose to abandon preferred habitats following encounters with wolves adds further support for the starvation-predation hypothesis," the researchers wrote.

In contrast, previous research has shown that elk -- the primary prey of wolves in the region -- will move when wolves approach within about 1,000 yards, even during winter. Elk also move from their preferred habitat to avoid wolves. The difference may be explained simply by the fact that moose are larger than elk and are more likely to stand their ground when approached by wolves, the researchers say.
Additionally, the nature of moose's preferred habitat -- described as "structurally complex" -- means it could serve as both a good food source and a refuge from wolves.

Still, it would be inaccurate to say that the presence of wolves doesn't affect moose movements.
"Although moose may be generally less responsive to predation risk from wolves, our detection of a heightened behavioral response during early winter suggests that anti-predator behavior is dynamic within and among species of ungulates," the researchers concluded.

Disrupting wolf movement may be more effective at protecting caribou

Woodland caribou populations have been dwindling towards local extinction across much of their range and scientists believe that predators, and specifically wolves, are a leading cause of the decline. Wolf populations are thought to have increased and expanded into caribou range due to the expansion of linear features, such as pipelines and roads, resulting from oil, gas and forestry development.
Controversial practices such as wolf culling and building fenced enclosures have been implemented to reduce the encounters between wolves and at-risk woodland caribou in the Canadian Oil Sands.
New research suggests there may be more effective and less invasive strategies to reduce the ability of wolves to encounter caribou. Researchers used motion-triggered cameras to capture photographs of wolves, caribou, and other wildlife species in the Canadian Oil Sands. The study captured more than 500,000 photographs that were used to study the habitat use patterns of the animals and test management strategies aimed at reducing the impacts of the linear developments on caribou.
The results showed that disrupting the ability of wolves to travel on the linear developments can reduce the ability of wolves to access caribou habitat, without building fences or culling wolves.
A paper describing the research is published in the March issue of the Journal of Animal Ecology, a British Ecological Society journal. The paper reveals new methods for using motion-triggered cameras to study animals. In doing so, researchers found that spreading logs, felling trees, or roughing the soil surface of the linear developments can be used as a habitat recovery strategy to disrupt the ability of humans and predators to access the critical habitats of at-risk caribou.
Disrupting the ability of animals to travel on linear developments is different than recovering the habitat. It takes decades for the habitat to recover in these northern caribou ranges and the cost of reclamation is considered prohibitive. However, disrupting travel on these same features can be more easily implemented, scaled-up across ranges, and reduce the predator's ability to encounter caribou immediately.
Jonah Keim, the lead author of the study, and his collaborators, Subhash Lele of the University of Alberta, Philip DeWitt of the Ontario Ministry of Natural Resources & Forestry, Jeremy Fitzpatrick (Edmonton, Alberta), and Noemie Jenni of Matrix Solutions Inc. have been conducting studies in ecology and data science for more than two decades. In 2011, members of the team co-authored a study revealing the abundances, diets and habitat use patterns of caribou, wolves and moose.
The study suggested that removing wolves may have unintended consequences. This January, the team released the results of a second camera study that shows how to reduce the use of caribou habitat by wolves. Surprisingly, they found that moving recreational snowmobiling trails away from caribou habitats may help draw wolves away from caribou - reducing the opportunistic killings of caribou by wolves.
Encounters between wolves and caribou can be managed by reducing wolf populations or by reducing the ability of wolves to access caribou. The research shows that the expansion of linear features has enabled wolves to more readily travel into caribou range and encounter caribou. Disrupting the ease-of-travel on linear features can reverse the impact on wolf-caribou encounters without wolf culling.

Return of the wolves: How deer escape tactics help save their lives

IMAGE: An adult gray wolf is caught on a wildlife camera in eastern Washington in 2015. view more 

Credit: University of Washington

As gray wolves continue to make a strong comeback in Washington state, their presence can't help but impact other animals -- particularly the ones these large carnivores target as prey.
White-tailed deer and mule deer, two distinct species common in Washington, are among wolves' favorite catch. Wolves will chase deer great distances -- sometimes upwards of 6 miles (10 kilometers) -- in search of a satisfying meal. How these two deer species respond to the threat of being pursued by wolves in the early years of this predator's return could shed light on changes to their behavior and numbers.
To help answer this question, researchers from the University of Washington and other institutions monitored the behavior and activity of wolves and deer in Washington for three years. They found that mule deer exposed to wolves, in particular, are changing their behavior to spend more time away from roads, at higher elevations and in rockier landscapes.
"In any particular ecosystem, if you have a predator returning, prey are unlikely to all respond similarly," said senior author Aaron Wirsing, an associate professor in the UW School of Environmental and Forest Sciences. "We show that wolves don't have a uniform effect on different deer species."
Their results were published Dec. 11 in the journal Oecologia.
Wolves were completely wiped out from Washington early last century, but began returning to the state from Idaho, Montana and Canada about a decade ago. The latest estimates now show about 200 wolves in packs across eastern Washington.
Both white-tailed and mule deer are important food for gray wolves. While they might look similar to an untrained eye, white-tailed deer and mule deer are very different animals: Mule deer are bigger, with large, dark ears and a black-tipped tail. White-tailed deer are smaller animals, boasting an unmistakably long tail with a white underside that stands straight up when alarmed.
Aside from their physical characteristics, the two species differ in how they escape from predators. When chased, mule deer "stot," a quick bound with all four legs touching the ground at the same time. This bounding gait helps them negotiate all types of terrain and can give them an agility advantage over predators in rocky, uneven areas where it might be hard to run.
By contrast, white-tailed deer sprint away from predators and rely on spotting them early enough to try to outrun them.
Keeping these known escape tactics in mind, the research team focused on the "flight behavior" of deer living in areas where wolves have returned and in areas without wolves. The researchers chose four distinct study areas, all near the small town of Republic, Washington. All four areas are home to both species of deer, but only two were occupied by known wolf packs at the time of the investigation.
In partnership with the Colville Tribes and the U.S. Forest Service, researchers set up wildlife cameras, captured and put collars on wolves and deer, and monitored the data from all of the collars over three years, from 2013 to 2016. This endeavor involved complex coordination and a dedicated team of UW students who were always ready to respond should an animal enter one of the traps.
"That part of eastern Washington is really special," said lead author Justin Dellinger, who completed the work as a UW doctoral student and now works at the California Department of Fish and Wildlife. "There is huge diversity of large mammals, including all of the native prey populations like big horn sheep, moose and deer. And now we're starting to see a full complement of native predators, like wolves, here as well."
Overall, the researchers found that mule deer in gray wolf areas changed their behavior to avoid wolves altogether -- mainly by moving to higher, steeper elevations, away from roads and toward brushy, rocky terrain. Alternately, white-tailed deer that favor sprinting and early detection as ways to escape from predators were more likely to stick to their normal behavior in wolf areas, sprinting across open, gently rolling terrain with good visibility -- including along roads.
"Mule deer faced with the threat of wolves are really changing their home ranges, on a large scale," Wirsing said. "They appear to have shifted kilometers away from where they had been prior to the return of wolves, generally going up higher where the terrain is less smooth and where wolves are less likely to hunt successfully."
These larger shifts among mule deer could affect hunting opportunities. Indeed, some hunters in eastern Washington have already reported seeing mule deer higher on ridges where they are less accessible than in past years, Wirsing said. Hunting for white-tailed deer likely won't change to the same degree with the presence of wolves, the results suggest.
Long term, changes among mule deer in wolf areas could affect other parts of the ecosystem, and perhaps reduce the number of deer-vehicle collisions. These possible impacts are tantalizing fodder for future studies, Wirsing added.

Wild carnivores stage a comeback in Britain

Once-endangered carnivorous mammals such as otters, polecats and pine martens have staged a remarkable comeback in Britain in recent decades, a new review shows.
The study found that - with the exception of wildcats - the status of Britain's native mammalian carnivores (badger, fox, otter, pine marten, polecat, stoat and weasel) has "markedly improved" since the 1960s.
The species have largely "done it for themselves" - recovering once harmful human activities had been stopped or reduced, according to scientists from the University of Exeter, Vincent Wildlife Trust, the Centre for Ecology and Hydrology and Scottish Natural Heritage.
Hunting, trapping, control by gamekeepers, use of toxic chemicals and destruction of habitats contributed to the decline of most predatory mammals in the 19th and early 20th Centuries.
"Unlike most carnivores across the world, which are declining rapidly, British carnivores declined to their low points decades ago and are now bouncing back," said lead author Katie Sainsbury, a PhD researcher at the Environment and Sustainability Institute at the University of Exeter's Penryn Campus in Cornwall.
"Carnivores have recovered in a way that would have seemed incredibly unlikely in the 1970s, when extinction of some species looked like a real possibility."
The researchers collected survey reports from the last 40 years and compared changes in the species' distribution extent and population sizes. They also reviewed human activities that have helped or hindered Britain's native carnivores in recent decades.
Otters have almost completely recolonised Great Britain. Badger populations have roughly doubled since the 1980s.
Polecats have expanded across southern Britain from Wales, and pine martens have expanded from the Scottish Highlands.
Fox numbers have risen since the 1960s, though an apparent decline in the last decade may be linked with dwindling rabbit numbers.
"Most of these animals declined in the 19th Century, but they are coming back as a result of legal protection, conservation, removal of pollutants and restoration of habitats," said Professor Robbie McDonald, head of Exeter's Wildlife Science group.
"The recovery of predatory mammals in Britain shows what happens when you reduce the threats that animals face. For the most part these species have recovered by themselves."
"Reintroductions have also played a part. Fifty one pine martens were recently translocated to Wales from Scotland and these martens are now breeding successfully in Wales. Otter reintroductions helped re-establish the species in the east of England."
Thought must now be given to how growing numbers of these animals interact with humans, the researchers say.
Some of the species can pose problems for gamekeepers, anglers and farmers, and work must be done to find ways to prevent conflict and allow long-term co-existence as the species expand their ranges and numbers.
Wildcats are the exception to the pattern of recovery. The species is now restricted to small numbers in isolated parts of the Scottish Highlands. Some estimates suggest there are as few as 200 individuals left. Their decline has largely been caused by inter-breeding with domestic cats, leading to loss of wildcat genes.
The status of stoats and weasels remains obscure.
Professor McDonald said: "These small and fast-moving predators are hard to see and to survey. Ironically, the best means of monitoring them is from the records of gamekeepers who trap them. People are key to carnivore recovery.
"By involving local communities from the outset, we have been able to secure the return of healthy numbers of pine martens to Wales. Translocations were needed because natural spread, something the Trust has been monitoring in polecats over the past 25 years, will take much longer for the slower breeding pine marten" said Dr Jenny MacPherson of Vincent Wildlife Trust.
The paper, published in the journal Mammal Review, is entitled: "Recent history, current status, conservation and management of native mammalian carnivores in Great Britain."

Indigenous hunters have positive impacts on food webs in desert Australia

Penn State

IMAGE: This is a drawing of Banded-hare wallabies from John Gould Mammals of Australia, 1845-63. view more 

Credit: Public Domain

Australia has the highest rate of mammal extinction in the world. Resettlement of indigenous communities resulted in the spread of invasive species, the absence of human-set fires, and a general cascade in the interconnected food web that led to the largest mammalian extinction event ever recorded. In this case, the absence of direct human activity on the landscape may be the cause of the extinctions, according to a Penn State anthropologist.
"I was motivated by the mystery that has occurred in the last 50 years in Australia," said Rebecca Bliege Bird, professor of anthropology, Penn State. "The extinction of small-bodied mammals does not follow the same pattern we usually see with people changing the landscape and animals disappearing."
Australia's Western Desert, where Bird and her team work, is the homeland of the Martu, the traditional owners of a large region of the Little and Great Sandy Desert. During the mid-20th century, many Martu groups were first contacted in the process of establishing a missile testing range and resettled in missions and pastoral stations beyond their desert home. During their hiatus from the land, many native animals went extinct.
In the 1980s, many families returned to the desert to reestablish their land rights. They returned to livelihoods centered around hunting and gathering. Today, in a hybrid economy of commercial and customary resources, many Martu continue their traditional subsistence and burning practices in support of cultural commitments to their country.
Twenty-eight Australian endemic land mammal species have become extinct since European settlement. Local extinctions of mammals include the burrowing bettong and the banded hare wallaby, both of which were ubiquitous in the desert before the indigenous exodus, Bird told attendees at the 2019 annual meeting of the American Association for the Advancement of Science today (Feb. 17) in Washington, D.C.
"During the pre-1950, pre-contact period, Martu had more generalized diets than any animal species in the region," said Bird. "When people returned, they were still the most generalized, but many plant and animal species were dropped from the diet."
She also notes that prior to European settlement, the dingo, a native Australian dog, was part of Martu life. The patchy landscape created by Martu hunting fires may have been important for dingo survival. Without people, the dingo did not flourish and could not exclude populations of smaller invasive predators -- cats and foxes-- that threatened to consume all the native wildlife.
Bird and her team looked at the food webs -- interactions of who eats what and who feeds whom, including humans -- for the pre-contact and for the post-evacuation years. Comparisons of these webs show that the absence of indigenous hunters in the web makes it easier for invasive species to infiltrate the area and for some native animals to become endangered or extinct. This is most likely linked to the importance of traditional landscape burning practices, said Bird.
Indigenous Australians in the arid center of the continent often use fire to facilitate their hunting success. Much of Australia's arid center is dominated by a hummock grass called spinifex.
In areas where Martu hunt more actively, hunting fires increase the patchiness of vegetation at different stages of regrowth, and buffer the spread of wildfires. Spinifex grasslands where Martu do not often hunt, exhibit a fire regime with much larger fires. Under an indigenous fire regime, the patchiness of the landscape boosts populations of native species such as dingo, monitor lizard and kangaroo, even after accounting for mortality due to hunting.
"The absence of humans creates big holes in the network," said Bird. "Invading becomes easier for invasive species and it becomes easier for them to cause extinctions." The National Science Foundation and the Max Planck Institute for Evolutionary Anthropology supported this work.

New study highlights importance of water resources for Andean bears

San Diego Zoo Global

A new study is shedding light on the importance of one critical resource for Andean bears living in the dry mountain forests of Peru: water. The study--a collaboration between the Norwegian University of Life Sciences and San Diego Zoo Global, with assistance from the Spectacled Bear Conservation Society-Peru--found that Andean bears focus much of their tree-rubbing behavior on shrubs and trees that are located on trails near water holes. Bears typically bite, claw and rub their body parts on trees, which is believed to be an important form of communication with other bears in the region. The discovery that this behavior occurs near water holes could have implications for future conservation programs. "It may seem obvious that water holes would be an important resource for Andean bears living in tropical dry forests--however, these results suggest that water holes are significant not just as sources of drinking water, but also as important sites where bears communicate with one another," said Russ Van Horn, Ph.D., San Diego Zoo Global scientist. "Because water holes are often the focus of activity by humans and their livestock, conservation planners will need to balance the interests of people and Andean bears in future programs."
A paper detailing results of the study, recently published in the journal Ursus, reported that while Andean bears didn't show a particular preference for tree-rubbing species, the locations of rubbed trees and shrubs were concentrated on trails near water holes. In the tropical dry forests of Peru, water is a relatively rare, albeit critical resource. Consequently, since livestock in the area also make use of water resources, conflicts may result between humans and bears.
This study is part of a larger effort by San Diego Zoo Global researchers and local partners to better understand Andean bear behavior and ecology. Andean bears are considered an umbrella species in the region, meaning that conservation programs aimed at protecting Andean bears will indirectly benefit other species in the Andes Mountains.
Andean bears are listed as Vulnerable on the International Union for Conservation of Nature's (IUCN) Red List of Threatened Species. They are native to the Andean countries of South America, and are sometimes known as spectacled bears because of white or light fur around their eyes. San Diego Zoo Global has been working with local partners to research and protect Andean bears in Peru. Andean bear habitat is being lost at a rate of about 2 to 4 percent per year as it is destroyed for mining operations, farming and timber harvest. The construction of new roads also fragments bear habitat. In addition, climate change is altering the bear's habitat in unpredictable ways. Andean bears now primarily live in dense mountain forests, making the species difficult to study. The dry tropical forest where this study occurred is more open than other kinds of Peruvian forests, making field research easier.