The shrinking moose of Isle Royale

IMAGE: The researchers measured the length, width and height of moose skulls to study the impact of climate change on the iconic Northwoods species. The team measured 662 moose skulls and... view more 

Credit: Sarah Bird/Michigan Tech

Researchers from Michigan Technological University know the smartest way to know a moose is by its brain. Specifically, skull measurements reveal information about body size, physiology and the conditions of a moose's early life. Put together, measurements through time reveal the health of a population and even changes in their environment.
For the booming moose population of Isle Royale, a key species in the world's longest running predator-prey study on the island, skulls have shrunk by about 16 percent over a 40-year period. The results were published recently in Global Change Biology.
Sarah Hoy, a research fellow in the School of Forest Resources and Environmental Science (SFRES) at Michigan Tech, led the study.
"The conditions you're born into have a massive impact on not only how big you are but also how long you're going to live," Hoy says. "This idea isn't new--what we're trying to do is establish how climate warming is affecting this iconic, cold-adapted species. We found evidence suggesting that moose experiencing a warm first winter tended to be smaller as adults and live shorter lives."
The results from the Isle Royale moose study are significant for several reasons, especially taken in the context of nearby moose populations.
In northern Minnesota, moose populations have been halved in the past 12 years. Many ecologists consider three main factors at play: predation, disease and climate change. In particular, the influence of warmer temperatures on moose nutritional condition and moose parasites, including a fatal brain worm parasite that is spread by white-tail deer, which have moved farther north into moose territory as the climate has gotten milder.
"The moose populations in northern Minnesota have tanked," Hoy says. "Climate is considered a main driver, whether it's direct through warmer winter temperatures causing heat stress and influencing the nutritional condition of moose or indirectly by establishing more favorable habitat for white-tail deer."
As Minnesota moose have declined, the Isle Royale moose have flourished, the population growing annually by more than 20 percent for the past six years. There are also no white-tail deer to spread parasites on Isle Royale. Yet the two groups of moose do share a similar climate, so Hoy and her team wondered if the skulls of Isle Royale moose would reveal adverse impacts of climate change.
Moose--who are naturally creatures of the north--prefer the cold. Warmer winters in the Northwoods raise concerns about how animal populations will adapt to climate change.
By measuring the length, width and height of moose craniums--on 662 skulls gathered on Isle Royale by hundreds of citizen science volunteers over four decades--clear patterns emerge. First, the skulls have decreased in size and, second, the evidence suggests that moose calves experiencing a warm first winter tended to be smaller as adults and live shorter lives. Hoy's collaborator Rolf Peterson, an SFRES research professor at Michigan Tech, helped haul in some of the skulls.
"The farthest we had to hike was 20 miles," Peterson says. "These aren't changes you can see out in the field; we're looking for trends over time in the whole population."
Hoy, Peterson and their collaborator John Vucetich, a professor of ecology at Michigan Tech, suggest the trends reflect a population in transition. Part of the Isle Royale moose's transition has to do with another of the island's key species--wolves.
It seems like a paradox: a growing population with shrinking individuals and shorter lifespans. Yet when the ecological balance of food availability and predation are considered, the contradiction makes more sense. As the wolves have died off on the island--only two remained during last year's winter study--the moose population has tripled in the past decade, reaching about 1,600 in the 2017 survey. Competition for food can also contribute to malnutrition and therefore smaller moose.
"Decreasing skull size may be an early indicator of population change," Vucetich says. "We're likely looking at a population in transition, and the healthiest transition would almost certainly involve restoring wolf predation to Isle Royale."
Adapting to climate change is already tough on moose; adding the present day's imbalance in the predator-prey dynamics puts additional stress on the Isle Royale ecosystem. Drawing from six decades of data, the Isle Royale Winter Study will come out later this winter to document the impacts of population change in the island's ecosystem.
In the meantime, the National Park Service plans to release its decision this winter on whether or not to reintroduce wolves to Isle Royale.

Wolves hunting moose undeterred by tailings ponds and pit mines

Wolf behavior undeterred by tailings ponds and pit mines

Study shows wolves hunt moose as usual in the Athabasca Oil Sands

University of Alberta

IMAGE: Two wolves peer into a wildlife camera in Alberta's Athabasca Oil Sands region. view more 

Credit: Wildlife Habitat Effectiveness and Connectivity, 2014

Wolves do not avoid areas of human disturbance when hunting moose in Alberta's oil sands region.
New UAlberta research shows that predation rates of moose have increased near areas of high human disturbance, but low human activity, such as tailings ponds and pit mines.
"Wolves are not avoiding these features," explained UAlberta PhD candidate Eric Neilson, who compared the population density of moose to the distribution of wolf-related moose deaths in the region. "In fact, they are using space near mines as they usually would, demonstrating that these spaces are not a deterrent."
If anything, Neilson says these spaces provide effective hunting ground for wolves.

Environmental changes
When habitat is cleared for mining or oil extraction, there are large changes to the landscape that create barriers around which wolves move. A similar effect, Neilson said, is shown around rivers.
"Wolves are coursing predators. This means that they like to move across the landscape to encounter their prey. It could be that the edge of the mine provides a feature similar to rivers that they can move along and around in the same way," he said.
However, the intensification of wolf activity and moose kills near the edges of these mines and tailings ponds is not shown near camps or upgrader sites, likely due to the presence of humans.

Future investigation
"There is a lot more research to be done in this area," said Neilson, adding the impact upon moose populations is not yet clear. "With any change in habitat that causes changes in animal behaviour, there are many factors to consider and much more we can learn about what is really going on here."

An alternative to wolf control to save endangered caribou

IMAGE: Mountain Caribou in British Columbia, Canada observed during a population census. view more 

Credit: Robert Serrouya

What happens when invasive and native species are eaten by the same predator? If the invasive species is abundant, the native species can go extinct because predator numbers are propped up by the invading species. This process is called "apparent competition" because on the surface it "appears" that the invading and native prey directly compete with each other, but really the shared predator links the two prey.

Apparent competition is an increasing problem, causing endangerment and extinction of native prey as abundant species colonize new areas in the wake of human-caused change to the environment. This is exactly what is happening to the iconic woodland caribou across North America. Prey like moose and white-tailed deer are expanding in numbers and range because of logging and climate change, which in turn increases predator numbers (e.g. wolves). With all these additional predators on the landscape, more caribou become by-catch, driving some herds to extinction.

A short-term solution would be to kill wolves but this can be seen as just a band aid, and is no longer politically acceptable in many jurisdictions. As a more ultimate solution, Serrouya and colleagues used a new government policy and treated it as an experiment, to maximize learning. The new policy was to reduce moose numbers to levels that existed prior to widescale logging, with an adjacent reference area where moose were not reduced. The results of this research are published in an article titled "Experimental moose reduction lowers wolf density and stops decline of endangered caribou," and is published today in the peer reviewed and open access journal PeerJ.

Following the reduction of moose using sport hunting, wolf number numbers declined, with wolf dispersal rates 2.5 × greater than the reference area, meaning that dispersal was the process leading to fewer wolves. Caribou annual survival increased from 0.78 to 0.88 for the Columbia North herd, located in the moose reduction area, but survival declined in the reference area (Wells Gray). The Columbia North herd probably stabilized as a result of the moose reduction, and has been stable for 14 years (2003 - 2017). By expanding their comparison across western Canada and the lower 48 states, they found that a separate herd subjected to another moose reduction was also stable, whereas at least 15 other herds not subjected to moose reductions are continuing to decline.

The results obtained by Serrouya and colleagues are similar to other studies that used more controversial approaches. For example, in Alberta, 841 wolves were removed in the Little Smoky caribou herd over 7 years, but results were as good or better using the less controversial approach of reducing invasive prey (moose). But, population stability is insufficient to achieve recovery goals for caribou, which require population growth. This conclusion suggests that several limiting factors and management levers must be addressed simultaneously to achieve population growth for caribou.

These levers include habitat protection, reducing invading prey, and if needed, short-term and focused predator removal.

Baits may be bolstering bear populations

New research reveals that baits used by hunters have become a substantial portion of black bears' diets. In northern Wisconsin, over 40% of the diet of harvested animals consisted of bait subsidies.

The widespread availability and consumption of these calorically rich baits--often high-sugar foods, such as cookies, donuts, and candies--may be bolstering the bear population density in the region. 

Thirty states permit hunting black bears, 12 of which allow baiting prior to the opening of the hunting season. However, the findings indicate that the goals and consequences of baiting policies should be re-evaluated.

"It's not surprising that bears are eating bear bait, but what is notable is the extent. Not only are these bears consuming bait just before they are harvested, but also throughout their lifetimes, which makes them one of the most highly subsidized populations of bears," said Dr. Rebecca Kirby, lead author of the Journal of Wildlife Management study.

Study doesn't support theory red and eastern wolves are recent hybrids, researchers argue

A team led by University of Idaho researchers is calling into question a widely publicized 2016 study that concluded eastern and red wolves are not distinct species, but rather recent hybrids of gray wolves and coyotes. In a comment paper that will publish Wednesday, June 7, in the journal Science Advances, the team examines the previous study and argues that its genomic data and analyses do not definitively prove recent hybridization -- but rather provide support for the genetic and evolutionary distinctiveness of red and eastern wolves.

"The history of these species is complex and certainly contains evidence for hybridization in the past. The question is timing," said Paul Hohenlohe, an assistant professor of biological sciences in the UI College of Science and the lead author of the comment paper. "The data and analyses aren't actually a good test of recent vs. older hybridization. In fact, the data are consistent with red and eastern wolves having a long evolutionary history as distinct lineages."

Hohenlohe co-authored the paper with an interdisciplinary team that included co-lead author Linda Rutledge, a research associate in the biology department at Trent University in Ontario, Canada; Lisette Waits, a Distinguished Professor in UI's College of Natural Resources Department of Fish and Wildlife Sciences; UI research scientist Jennifer Adams; UI postdoctoral researcher Kimberly Andrews; and other researchers from Trent, the University of Georgia and Northland College.

The team agrees with one conclusion of the previous study: Admixture is a part of the evolutionary history of North American canids, and conservation policy needs to take into account naturally occurring hybridization and population admixture. But they urge policymakers not to close the case on the origins of red and eastern wolves when making conservation decisions.

"Policymakers are making decisions about how much money, effort and energy to put into recovery and management efforts of the red wolf and eastern wolf," said Waits, who has served on U.S. Fish and Wildlife Service recovery teams for the red wolf. "It is important for them to understand that the conclusions stated in the vonHoldt et al paper are not universally supported by the scientific community, and there are alternative interpretations and remaining questions about the evolutionary history of canids in North America."

The UI-led team addresses several concerns with the previous study, which was led by Princeton University's Bridgett vonHoldt and published in Science Advances in July 2016. The team questions the vonHoldt study's use of genomic data from a few individual coyotes and eastern wolves that may not be the best representatives of those groups, as well as the authors' conclusion that genomic data demonstrate a lack of unique ancestry in red and eastern wolves.

The team's review of the vonHoldt study's analyses of genomic data finds the data do not establish definitive evidence for a recent hybrid origin of red and eastern wolves, but rather are consistent with multiple evolutionary possibilities. These possibilities include red wolves originating from a hybridization event tens of thousands of years ago, or diverging as a distinct lineage as long as 100,000 years ago and experiencing some subsequent hybridization.

The UI-led team finds that other data from the previous study, such as the amount of unique genetic variation found only within red or eastern wolves, further support the genetic distinctiveness of these taxa.

Hohenlohe, Waits and their collaborators are conducting further analyses about red and eastern wolf origins, and expect to continue to generate new data and hypotheses about the evolutionary relationships among these species, the gray wolf and the coyote.

"Genomics is an exciting new contribution to wildlife conservation, but it brings with it a responsibility to provide a coherent interpretation of complex data within the context of natural history," Rutledge said. "This is especially important for species at risk of extinction where the consequences involve the permanent loss of evolutionary potential. We get closer to the evolutionary truth when we use a holistic approach that includes multiple sources of information."

Wolves need space to roam to control expanding coyote populations

Wolves and other top predators need large ranges to be able to control smaller predators whose populations have expanded to the detriment of a balanced ecosystem.

That's the main finding of a study appearing May 23 in Nature Communications that analyzed the relationship between top predators on three different continents and the next-in-line predators they eat and compete with. The results were similar across continents, showing that as top predators' ranges were cut back and fragmented, they were no longer able to control smaller predators.

"Our paper suggests it will require managing for top predator persistence across large landscapes, rather than just in protected areas, in order to restore natural predator-predator interactions," said co-author Aaron Wirsing, an associate professor at the University of Washington's School of Environmental and Forest Sciences.

Gray wolves historically lived across vast swaths of North America, particularly in the western states and Canadian provinces. Coyotes, a smaller predator kept in check by wolves, appear to have been scarce in areas once dominated by wolves. As human development shrank territories for wolves, however, the wolf populations became fragmented and wolves no longer had the numbers or space to control coyotes, whose populations in turn grew.

The same story is at play in Europe and Australia, where the researchers examined the relationship between gray wolves and golden jackals, and dingoes and red foxes, respectively. As with America, when the top predator's range was slashed, the second-tier predators ballooned and ecosystems became imbalanced.

"This research shows that apex predators like dingoes and wolves need large, continuous territories in order to effectively control the balance of their ecosystems," said lead author Thomas Newsome of Deakin University and the University of Sydney in Australia. "Humans need a greater tolerance of apex predators if we want to enjoy the environmental benefits they can provide."

Only in the northern regions of Canada and parts of Alaska do wolves still roam across the large landscapes they once occupied. Elsewhere in North America, patchwork conservation efforts have brought wolves back in areas such as Yellowstone National Park, the northern Rockies, and eastern Washington and Oregon. Though wolves are on the upswing in these regions, their populations are likely too isolated to control the pervasive coyote and other small predators.

In some areas, the increase in wolves is actually helping some predators that might be a couple of rungs lower on the food chain, like the red fox. But regardless of whether the presence of more wolves helps or hurts other predators, that effect is likely dampened when wolf populations are fragmented.

This calls into question what makes for effective conservation. At least for wolves, Wirsing said, prioritizing activities that connect landscapes and attempt to rejoin isolated populations should be considered, he said.

"This reframes the debate ? what we really need to do is connect areas if we want predators to play their historical roles," he said.

The researchers used bounty hunting data from all three continents to map the top predators' historical ranges. They then mapped the range over time for the three smaller predators, looking to see where they overlapped. The researchers found that top predators such as wolves and dingoes could suppress coyotes, red foxes and jackals only when the top predators lived at high densities and over large areas. Additionally, wolves and dingoes exert the most control closest to the core of their geographic range.

In places like Yellowstone and eastern Washington and Oregon, however, smaller wolf populations are too far removed from the remaining core of the species' distribution to really make a difference in controlling coyote numbers.

Fewer wolves aren't the only reason coyotes have proliferated everywhere in North America. Coyotes are generalists that can live almost anywhere and have basically followed humans, eating our food and, in some cases, household pets. There have even been sightings in many metropolitan areas, including downtown Chicago.

"Coyotes have essentially hitched a ride with people," Wirsing said. "Not only do we subsidize coyotes, but we also helped them by wiping out their predators ? wolves."

The researchers plan to test whether similar patterns occur for other species pairs that compete strongly. They also call for more research comparing the ecological role of top predators on the edge of their geographic range, especially in human-modified environments.

"It will be interesting to see the influence of large predators on smaller predators in other parts of the world, especially the role of the big cats such as jaguars, leopards, lions and tigers," said co-author William Ripple of Oregon State University.

Measuring the impact of a changing climate on threatened Yellowstone grizzly bears

Climate change is altering the environment in Yellowstone National Park and its surrounding region and scientists at the University of California San Diego and Unity College are studying its impacts on the diets of threatened grizzly bears.

A study published May 11 in PLOS ONE focused on modeling the diets of grizzly bears in Cooke City Basin, Montana, part of an area designated as the Greater Yellowstone Ecosystem (GYE). Evidence from the team's research in the study area and a recent habitat-selection study by Montana State University indicates that grizzly bears continue to forage for whitebark pine seeds as a diet staple. Diet proportions derived from isotopic data, however, suggest that some bears could be responding to reductions in whitebark trees by consuming more plants and berries.

Once ubiquitous in western North America, the slow-growing whitebark pine trees have declined in recent decades and are now listed as endangered by the International Union for Conservation of Nature. Warming temperatures have led to shorter and milder winters, increasing beetle infestations and further threatening whitebark pine mortality. Other potential food sources for grizzlies such as trout and ungulates have also declined in the region. 

"Whitebark pine trees have declined due to an introduced fungal disease called blister rust, and, more recently, to increased infestation by the mountain pine beetle, which is exacerbated by climate change," said study coauthor Carolyn Kurle, an assistant professor at UC San Diego's Division of Biological Sciences. "Such declines further highlight the need to monitor diets of grizzlies as the environment continues to change."

Lead author Jack Hopkins, a former postdoctoral researcher in Kurle's lab at UC San Diego and currently an assistant professor at Unity College, and his team measured stable isotopes in bear hair and related their abundances to those found in their foods.

"Stable isotope analysis is a powerful ecological tool for reconstructing the diets of animals," said Hopkins. "Instead of investigating the diets of animals based on what's eliminated (feces), we estimate the importance of major food sources to animals based on what's assimilated into their tissues. Using stable isotope analysis to conduct a retrospective diet analyses can shed light on how animals, such as Yellowstone grizzlies, have responded to changes in food availability on the landscape."

Previous research has shown that whitebark pine seeds--often cashed in large middens by red squirrels--are raided by grizzlies in the fall, fueling reproduction and ensuring the survival of grizzlies in the region. A main reason threatened grizzly bears have remained protected for decades is because it has not been clear how declines in whitebark pine trees, and thus the seeds they provide bears, will impact population trends over the long term.

Because their inferences are limited to a small area in the region and a small number of bears, the researchers recommend a large-scale study and urge others to use their new modeling framework to investigate the diets of other species of concern.

"Such analyses could be used to monitor grizzly bear recovery efforts and inform other wildlife conservation and management programs worldwide," Hopkins added.

Only two Isle Royale wolves

For the second year in a row, the Isle Royale wolf population remains a mere two. Researchers from Michigan Tech say that as the wolf population stays stagnant, the moose population will continue to grow at a rapid pace. And this could have a significant impact on the island's famed forests.

According to Rolf Peterson, a research professor at Michigan Tech and co-author of the report, the Isle Royale wolves are no longer serving their ecological function as the island's apex predator--the creature at the top of the food chain. With only two wolves left on the island, the moose population has grown to an estimated 1,600. 

Without wolf predation, says John Vucetich, a professor of ecology at Michigan Tech and report co-author, the moose population could double over the next three to four years. And more moose means more vegetation is eaten. The observations were reported in this year's Winter Study, which marks the 59th year of monitoring wolves and moose on Isle Royale, the longest running predator-prey study in the world. 

Wolf Genetics

Where have all the island wolves gone? The answer lies in genetics. The population crash on Isle Royale is the result of inbreeding--the remaining wolves are not only father and daughter, they are also half siblings who share the same mother.

Researchers believe the two have probably mated at least once in the past: in 2015, an approximately nine-month-old pup was spotted with the two adults. That pup, however, did not appear healthy. Researchers noted a visibly deformed tail, small stature and possibly abnormal posture. Peterson and Vucetich were not surprised when the pup failed to appear with the adults in 2016.

The remaining wolves are not expected to successfully reproduce in the future, either. Both animals are approaching old age--the female is seven years old and the male is nine--and no one can predict how much longer either wolf will live. Further complicating matters, the female wolf has been observed aggressively rejecting the male as a mate.

But even if the pair were to produce a healthy pup, it would likely have little impact on the Isle Royale ecosystem. In the case of these wolves, extreme inbreeding makes the population's natural recovery unlikely. The wolves' numbers started plummeting in 2009, declining by 88 percent from 24 to 2 wolves. Vucetich and Peterson believe this is a result of inbreeding, and all geneticists who have studied the situation agree that recovery is unlikely without new genetic material.

At the end of 2016, the National Park Service published a Draft Environmental Impact Statement (DEIS) to determine how best to manage the wolves on Isle Royale. The DEIS discussed four potential courses of action. According to the document, NPS would prefer a time-limited introduction of new wolves--up to 20 to 30 wolves selected to maximize both genetic diversity and restore predation to the ecosystem. NPS estimates that the process to introduce the number of wolves identified in the plan would take between three to five years. Public review of the document concluded in mid-March, and the NPS is reviewing all comments. A final decision is expected in the fall.

More Moose 

The 2017 moose census puts the Isle Royale herd at approximately 1,600 members. According to the report, the multiyear trend shows the moose population has been growing at a six-year average rate of 21.6 percent. Peterson and Vucetich credit this rapid growth to several factors: high reproduction rates, low rates of mortality due to wolf predation, mild winters and an abundance of forage. 

But this abundance of forage may not last. According to recent findings, under the island's current conditions, the moose population could double over the next three to four years. If this happens, the number of Isle Royale moose would reach an unprecedented high for the project's six-decade history. And this could result in high levels of browsing on the island's vegetation.

"Everything we're seeing on Isle Royale is consistent with our past understanding of the ecosystem's dynamics," says Vucetich. "We have every reason to expect the moose population will continue to grow and increasingly impact the forest."

Moose aren't the only Isle Royale residents experiencing a population boom with a dwindling number of wolves. The report notes that the number of beaver colonies has increased dramatically over the past six years, from approximately 100 to nearly 300. 

"Wolves are the only significant predator of beaver on Isle Royale," says Peterson. "Beaver were nearly extinct across North America 200 years ago. At Isle Royale, they're now at unprecedented levels."

With wolves no longer serving their predatory function, Isle Royale's ecosystem could soon look dramatically different.

Wolves often rely on human foods

On landscapes around the world, environmental change is bringing people and large carnivores together--but the union is not without its problems. Human-wildlife conflict is on the rise as development continues unabated and apex predators begin to reoccupy their former ranges. Further complicating matters, many of these species are now reliant on anthropogenic, or human, foods, including livestock, livestock and other ungulate carcasses, and garbage.

Writing in BioScience, Thomas Newsome, of Deakin University and the University of Sydney, and his colleagues use gray wolves and other large predators as case studies to explore the effects of anthropogenic foods. They find numerous instances of species' changing their social structures, movements, and behavior to acquire human-provisioned resources. For instance, in central Iran, gray wolves' diets consist almost entirely of farmed chickens, domestic goats, and trash.

Other instances of these phenomena abound. In a similar case in Australia, dingoes gained access to anthropogenic foods from a waste facility. The result, according to the authors, was "decreased home-range areas and movements, larger group sizes, and altered dietary preferences to the extent that they filled a similar dietary niche to domestic dogs." Moreover, wrote the authors, "the population of subsidized dingoes was a genetically distinct cluster," which may portend future speciation events. Hybridization among similar predator species may also contribute to evolutionary divergence: "Anthropogenic resources in human-modified environments could increase the probability of non-aggressive contact" between species. According to the authors, "If extant wolves continue to increase their reliance on anthropogenic foods, we should expect to observe evidence of dietary niche differentiation and, over time, the development of genetic structure that could signal incipient speciation."

Wolves' use of anthropogenic food could have serious implications for wider conservation efforts, as well. In particular, Newsome and his colleagues raise concerns about whether wolf reintroduction and recolonisation programs will meet ecosystem-restoration goals in human-modified systems. Managers will need to consider "how broadly insights into the role played by wolves gleaned from protected areas such as Yellowstone can be applied in areas that have been greatly modified by humans," say the authors.

Newsome and his colleagues call for further research--in particular, "studies showing the niche characteristics and population structure of wolves in areas where human influence is pervasive and heavy reliance on human foods has been documented." Through such studies, they argue that "we might be able to ask whether heavy reliance of anthropogenic subsidies can act as a driver of evolutionary divergence and, potentially, provide the makings of a new dog."

Coyotes can't match wolves' hunting prowess

Eastern wolves once roamed forests along the Atlantic coast, preying on moose, white-tailed deer and other hooved mammals collectively known as ungulates. As the wolf population plummeted via the rifle and the trap, however, the eastern coyote inherited the status of apex predator in those habitats.

But a study from John Benson and colleagues provides evidence that the eastern coyote hunts moose and other large prey far less frequently than does the eastern wolf -- instead preferring to attack smaller game or scavenge human leftovers.

The findings help resolve long-standing questions about whether eastern coyotes have filled the ecological niche left vacant when the eastern wolf became threatened, Benson said.

"Wolves rely on large prey to survive," said Benson, assistant professor of vertebrate ecology who conducted the research as a doctoral student at Trent University. "But the smaller size of coyotes appears to give them dietary flexibility to survive on a wider variety of food and prey sizes, making them less predictable predators of large prey.

"Having a top predator that preys consistently on large animals like deer and moose may be an important part of maintaining stable predator-prey dynamics and healthy, naturally functioning ecosystems."

After GPS-tracking 10 packs of eastern wolves and analyzing their kill sites in Ontario, the team estimated that the wolves consumed 54 percent of their ungulate meat from moose and 46 percent from white-tailed deer. By contrast, eight packs of eastern coyote ancestry that occupied separate but neighboring territories got just 11 percent of their ungulate meat from moose and 89 percent from deer.

The eastern wolf weighs between 50 and 65 pounds; the eastern coyote typically hits 40 to 50. Though the extra weight gives eastern wolves a greater chance of killing a moose - or at least surviving the encounter - it also demands the greater caloric intake that moose and other meaty prey can provide.

Because wolves need to feed on large prey, their populations tend to rise and fall together, Benson said. Wolves may kill many moose during a winter, for instance, depleting their numbers. With fewer moose available, the wolf population declines, boosting the moose population, which in turn boosts the wolf population, and so on.

Yet the buffet-style menu of the eastern coyote means that its numbers can remain steady or even rise without large prey if alternative food is abundant. This opportunistic diet, Benson said, might also be driving erratic population swings among those lower on the food chain.

"It's important to understand the role that wolves play in ecosystems and to not assume that smaller predators ... perform the same ecological functions," Benson said. "If coyotes start hammering white-tailed deer, and deer start to decline, then (coyotes) can just eat rabbits or squirrels or garbage but continue to prey on deer, too. So we think that could be a destabilizing element.

"There are some areas where you've got way too many white-tailed deer in the east, and then you've got other areas where hunters are concerned because the deer are declining. That speaks to the fact that coyotes are an unpredictable predator."

The study is timely: Canada recently designated the eastern wolf as threatened, with the vast majority of eastern wolves living protected in Ontario's Algonquin Provincial Park.

Human-caused mortality has limited efforts to expand the population beyond Algonquin Park, Benson said, which is made worse by the fact that wolves there are likely naïve to the dangers posed by humans. Another issue: Eastern wolves readily breed with eastern coyotes in the wild, making it difficult to maintain a pure lineage.

"Is there a way to get them to expand numerically and geographically outside of the park? We're not sure at this point," said Benson, who provides advice to a team now developing a recovery plan. "One thing that can be managed is human-caused mortality, so if we can provide additional protection, that should put them on equal demographic footing.

"It's an incredibly challenging situation that is complicated by the interactions of these wolves with coyotes and humans. If the park stays the same, there's no immediate reason that they would go extinct. However, we wouldn't want to go forward with that as our only plan because it offers little chance for expansion."

Though large-scale reintroduction across eastern North America will probably not occur soon, Benson said the study emphasizes the value of preserving delicate predator-prey balances that ecosystems have calibrated over millennia.

"Our work suggests that there's an ecological role that wolves play that won't be played by other animals," he said. "That's probably a role that's worth conserving on landscapes, even outside protected areas. If we're interested in restoring landscapes to a more natural, functioning ecosystem, this would be an important part of that."

Snow leopard and Himalayan wolf diets are about one-quarter livestock

Around a quarter of Himalayan snow leopard and wolf diets are livestock, the rest being wild prey, according to a study published February 8, 2017 in the open-access journal PLOS ONE by Madhu Chetri from Inland Norway University of Applied Sciences, Norway, and colleagues.

Killing livestock creates conflicts between top predators and pastoral communities, and is a main challenge for conserving snow leopards, which are endangered, and Himalayan wolves, which are rare. These wolves prefer the open grasslands and alpine meadows that are also frequented by pastoral herders, and snow leopards prefer the steep terrain associated with montane pastures. To assess prey preferences of these carnivores, Chetri and colleagues analyzed DNA and hairs in 182 snow leopard scats and 57 wolf scats collected in the Central Himalayas, Nepal.

The researchers found that in keeping with the predators' habitats, snow leopards preferred cliff-dwelling wild prey such as bharal, while wolves preferred plain-dwelling wild prey such as Tibetan gazelles. In addition, livestock comprised 27% of the snow leopard diet and 24% of the wolf diet. Livestock occurred more than twice as frequently in scats from male snow leopards than in scats from females. Although livestock constitutes a substantial proportion of the predator's diets, little is known about the actual predation impact on the pastoral communities. Hence, the researchers' forthcoming work focuses on estimating livestock mortality rates and identifying factors associated with livestock loss.

Brown bears reduce wolf kill rates says USU ecologist

Contrary to popular assumptions, researchers on two continents find wolves kill less often in the presence of brown bears

UTAH STATE UNIVERSITY

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IMAGE: IN NORTH AMERICA'S YELLOWSTONE NATIONAL PARK, HUNGRY WOLVES WAIT TO ACCESS THEIR ELK KILL AS BROWN BEARS FEAST ON THE SPOILS. UTAH STATE UNIVERSITY ECOLOGIST AIMEE TALLIAN AND COLLEAGUES REPORT... view more 

CREDIT: DANIEL STAHLER, NATIONAL PARK SERVICE

LOGAN, UTAH USA - If you've ever been elbowed out of the way at the dinner table by older, stronger siblings, you'll identify with wolves competing with larger bears for food. A study by Utah State University ecologist Aimee Tallian and colleagues reveals wolves might be at more of a disadvantage than previously thought.

Tallian is lead author of a paper examining competition between wolves and brown bears on two continents published Feb. 8, 2017, in Proceedings of the Royal Society B[DOI: 10.1098/rspb.2016.2368]. 

"Wolves and brown bears coexist across most of their range," says Tallian, who completed a doctoral degree from USU in 2017. "Although competition between predators such as these is widespread in nature, we know little about how brown bears affect wolf predation."

With colleagues in Scandinavia and North America, Tallian examined how brown bears affected wolf kill rates at study sites in northern Europe and Yellowstone National Park.

"We found an unexpected pattern," she says. "Wolves killed less often in the presence of brown bears, which is contrary to the common assumption that wolves kill prey more often to compensate for loss of food to bears."

Tallian says the consistency in results between the systems on different continents suggests brown bear presence actually reduces wolf kill rate, but the researchers aren't sure why.

They surmise wolves, unlike lynx and mountain lion, may not be quickly abandoning their kills, as bears move in take advantage of the spoils.

"The wolves may be hanging around longer, waiting their turn to gain access to food," Tallian says.

She and her colleagues also wonder if wolves kill less frequently because it takes them longer to find prey.

"We think this may be the case, in the spring, when newborn ungulates make easy pickings for bears," Tallian says. "It may simply take more time for wolves to find calves, when there are fewer of them."

Interactions between apex predators can either relax or strengthen their effect on prey and predator populations, she says.

"The team's results suggest that ignoring such interactions may underestimate the effect competition between predators can have on predator populations," Tallian says. "In addition, it's possible to overestimate the impact of multiple predators on prey populations."

Machu Picchu in Peru is home to a biologically important species: the Andean bear

A recent wildlife survey led by SERNANP (Servicio Nacional de Áreas Naturales Protegidas por el Estado) and WCS (Wildlife Conservation Society) in the Historic Sanctuary of Machu Picchu in Peru has confirmed that the world-famous site is also home to a biologically important and iconic species: the Andean bear (Tremarctos ornatus).

Funded by the Andean Bear Conservation Alliance, the U.S. Agency for International Development, and the Gordon and Betty Moore Foundation, the year-long survey revealed the presence of Andean bears in more than 95 percent of the 368-square-kilometer study area, which includes the famous Incan ruins of Machu Picchu, one of the most visited places in South America. While it was previously known that Andean bears existed in the sanctuary, the new survey's findings reveal a much wider presence of bears throughout the protected area.

The Historic Sanctuary of Machu Picchu is classified as a World Heritage site by UNESCO (the United Nations Educational, Scientific, and Cultural Organization) and is one of only 35 sites worldwide listed as a mixed natural and cultural site. The findings from this survey are critical for establishing a baseline for future assessments and to plan for the long-term conservation of Andean bears both within and beyond the sanctuary.

"It is amazing that this world famous location is also important habitat for Andean bears," said Dr. Isaac Goldstein, Coordinator of WCS's Andean Bear Program. "The results of the survey will help us to understand the needs of this species and how to manage Andean bears in this location."

With a range stretching from Venezuela to Bolivia, the Andean bear inhabits the mist-shrouded montane forests and upland grasslands of the Andes Mountains and is South America's only native bear species. The Andean bear is sometimes called the spectacled bear due to yellowish or white patches that surround its eyes. The species features prominently in the cultural fabric of the region, yet much is still unknown about the behavior and ecology of the Andean bear.

The survey results also show that the Andean bears of Machu Picchu are not an isolated population, but part of a much larger population connected by montane grasslands that occur over an elevation of 3,400 meters (more than 11,000 feet above sea level). Understanding this connectivity will help wildlife managers to maintain the corridors needed for healthy bear populations. The survey itself is part of a larger effort by SERNANP and its partners to monitor Andean bears across the Machupicchu-Choquequirao Landscape, a large mountainous region containing both archeological sites and natural areas.

Fieldwork to collect data on the presence of Andean bears in the Historic Sanctuary of Machu Picchu was conducted between August 2014 and September 2015. A team of more than 30 trained researchers and park officials looked for signs of bears in a variety of habitats in the Machu Picchu protected area, ranging from Andean rainforest to montane grasslands. The study area was divided into sections 16 square kilometers in size (more than 6 square miles, the typical size of a female Andean bear's range) to evaluate the bear's presence in the protected area. Researchers looked for bear activity such as scat, footprints, and signs of feeding on terrestrial bromeliads (plants native to tropical and subtropical regions) along 166 kilometers (more than 100 miles) of transects throughout the sanctuary.

In addition to finding signs of bears in most of the sanctuary, the research team also determined that the presence of cattle is a potential risk to Andean bears in the sanctuary. The survey results will help inform the effective management of the Historic Sanctuary of Machu Picchu, the most visited protected area in Peru.

WCS has contributed to extensive research on the ecological needs of the Andean bear throughout its range. In 2014, WCS published the document "Andean Bear Priority Conservation Units in Bolivia and Peru" that consolidated information from 25 Andean bear experts on the distribution of the species and recommendations for conservation. In the U.S., WCS's Queens Zoo is home to the only Andean bear exhibit in New York City. Queens Zoo Director and Curator Scott Silver serves as Coordinator for the Andean Bear Species Survival Plan (SSP), a cooperative breeding program administered by the Association of Zoos and Aquariums that ensures genetic variability within accredited zoo populations.

The Eurasian grey wolf, Canis lupus lupus, has spread across Germany

Since the year 2000, the Eurasian grey wolf, Canis lupus lupus, has spread across Germany. For Ines Lesniak, doctoral student at the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), and her colleagues, a good reason to have a closer look at the small "occupants" of this returnee and to ask the question whether the number and species of parasites change with an increasing wolf population. This was the case, because the number of parasite species per individual wolf increased as the wolf population expanded. Furthermore, cubs had a higher diversity of parasite species than older animals. The good news: wolf parasites do not pose a threat to human health. The results of this study were published in the scientific online journal "Scientific Reports" of the Nature Publishing Group.

In the course of a long-term study of wolf health in Germany, the internal organs of 53 wolf carcasses were studied in detail. They came from wolves which had died in traffic accidents or were illegally killed between 2007 and 2014.

"Whereas tapeworms are recognisable with the naked eye, the identification of single-celled Sarcocystis parasites was a real challenge, since the species of this genus do not differ morphologically," explains Lesniak.

According to their developmental cycle, endoparasites can be grouped into two types: Some, such as many tapeworms, infect their hosts directly. Others, such as Sarcocystis parasites, first live in an intermediate host, the prey animal of the wolf, and reach their final host, the wolf, only if the intermediate host has been consumed by the final host. With the faeces of the final host, these parasites are released back into the environment. Potential prey animals of the wolf feed then on vegetation that was previously contaminated with the parasites. The parasites thereby invade the intermediate host and settle in the muscle flesh. Roe deer, red deer and wild boar are such intermediate hosts in central Europe. When these are eaten by a wolf, the parasites infect the final host -- the wolf -- and reproduce in its intestines.

By applying sophisticated molecular genetic analyses, the scientists identified 12 Sarcocystis species in the wolf carcasses. They also found four tapeworm species (cestodes), eight roundworm species (nematodes) as well as one fluke species (trematode). In order to examine parasite infections also in the wolf's large prey species, the team collected internal organs of shot prey animals from hunting parties.

In Germany, wolves mainly feed on roe deer, but also red deer and wild boars. Small mammals, such as hares, voles or mice, are very seldom "on the menu." The identified parasites provide indirect evidence for this insight, since fox tapeworms were found in only one of the 53 wolves. Fox tapeworms are transmitted by mice and can occur in all canids, but particularly frequently in foxes. "Good news," Lesniak says, because the larvae of fox tapeworms can cause severe diseases in humans.

The scientists found that the infestation of wolves with parasites varied during their lifetime. "Cubs carry many more parasite species than yearlings or adults." According to Ines Lesniak, such variation in parasite species prevalence can be explained by the more robust immune system of older wolves. Wolves, just like any other wild canid -- other than domestic dogs -- are never dewormed, after all.

Wolves that died at the beginning of the study period had a lower parasite diversity than those who died later. "The bigger the population, the more often wolves are in contact with each other and their prey, and the more often they became infected with different parasites," Lesniak summarises the results.

Currently, there are 46 wolf packs settled within Germany. A pack consists of the parents as well as the cubs of the current and the previous year and can comprise up to ten individuals. "Genetic analyses conducted by our cooperation partners for this study show that the ancestors of the Central European lowland population, which nowadays ranges from Germany to Poland, originated from Lusatia in eastern Germany," Lesniak says. This population was probably initiated by individuals who migrated from the Baltic region at the beginning of the millennium and settled between southern Brandenburg and northern Saxony. From there, they began to spread across northeastern Germany and southwestern Poland, a process which continues to this day.

"Wolves are shy, wild animals. Thus, contact between people and wolves is rare," Lesniak emphasises. "Nevertheless, hunters should boil the leftovers of shot game thoroughly before feeding this to their hunting dogs, in order to avoid possible parasite infections," warns Lesniak. It is also essential to regularly deworm hunting dogs in regions occupied by wolves.

Occasionally, it has been reported that wolves come closer to residential areas; sheep farmers are complaining about losses. "It may well be that today's wolves have learnt that it is easier to find food closer to humans -- those, who once eradicated their wolf forefathers" presumes Lesniak. Of course, it is more convenient for a wolf to break into a sheep enclosure than to chase roe deer in the forest. Therefore, the implementation of appropriate protective measures of domestic animals is very important and now also financially supported by the government in Germany.

Tigers could roam again in Central Asia

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IMAGE: THIS IS AN ARTIST'S DEPICTION OF A CASPIAN TIGER. view more 

CREDIT: HEPTNER AND SLUDSKIY 1972

Caspian tigers, some of the largest cats that ever lived -- up to 10 feet long and weighing more than 300 pounds -- met a grim end in the middle of the 20th century. 

Until the mid-1960s when they were designated as extinct, they ranged from modern-day Turkey through much of Central Asia, including Iran and Iraq, to northwestern China. The reasons for their extermination are many: poisoning and trapping were promoted by bounties paid in the former Soviet Union until the 1930s; irrigation projects during the Soviet era destroyed the tugay woodlands (a riparian and coastal ecosystem of trees, shrubs and wetlands) and reed thickets that were critical tiger habitat; and the cats' prey disappeared as the riparian habitat vanished. 

But there is a chance that tigers -- using a subspecies that is nearly identical, genetically, to the extinct Caspian -- could be restored to Central Asia.

A study published online in the journal Biological Conservation lays out the options for restoring tigers to Central Asia and identifies a promising site in Kazakhstan that could support a population of nearly 100 tigers within 50 years.

"The territory of the Caspian tiger was vast," said Professor James Gibbs, a member of the research team and a conservation biologist who is director of the Roosevelt Wild Life Station at the College of Environmental Science and Forestry (ESF) in Syracuse, New York. "When they disappeared, the number of nations that hosted tiger populations was reduced by more than half." 

The researchers say introducing tigers in a couple of locations in Kazakhstan won't make a widespread difference immediately but it would be an important first step.

"The idea of tiger reintroduction in Central Asia using the Amur tiger from the Russian Far East as an 'analog' species has been discussed for nearly 10 years. It met with considerable support from the government of Kazakhstan in 2010 during the Global Tiger Forum in St. Petersburg, Russia," said Mikhail Paltsyn, an ESF doctoral candidate who oversaw analytical aspects of the study. 

"But the program needed a strong scientific foundation to evaluate the full habitat potential for tigers and to better explore different possible outcomes of the reintroduction in different scenarios," Paltsyn said. 

In addition to Paltsyn and Gibbs, the research team includes ESF scientists Liza Yegorova, a recent master's graduate; Dr. Igor Chestin, director of WWF-Russia; and Dr. Olga Pereladova, director of WWF Central Asia Program. Paltsyn is a member of the International Union for Conservation of Nature Cat Specialist Group and has served as a consultant with the World Wide Fund for Nature (WWF) and United Nations Development Programme.

The scientists say two factors have combined to raise the possibility of restoring tigers to the Ili-Balkhash region of western Kazakhstan:

* The breakup of the Soviet Union and introduction of market economies in newly established states has led to the recovery of tiger habitats in some areas as state-sponsored agricultural programs along rivers were abandoned.
* Recent work in phylogenetics (the study of evolutionary history) indicates Caspian tigers were closely related to Amur tigers that still exist, making Amur tigers a likely "analog" species for restoration of tigers to the region. 

But Paltsyn laid out the challenges that would need to be addressed before tigers start roaming the landscape again. 

"First, it is necessary to stop riparian zone degradation caused by uncontrolled fires. Second, it is vital to restore wild ungulate (broadly defined as a hoofed mammal) populations in the area. That, alone, could take five to 15 years," Paltsyn said. "Third, human safety and socio-economic benefits for local populations need to be addressed to provide a sustainable future for both tigers and people. And, finally, water consumption from the Ili River needs to be regulated in both Kazakhstan and China to support sufficient water level in Balkash Lake for tugay and reed ecosystems - the main tiger habitat. However, WWF and the government of Kazakhstan seem to be ready to deal with all these difficult issues to bring tigers back to Central Asia." 

Tiger reintroduction has support from the Kazakhstan government and local communities because of potential economic benefit from wildlife tourism, small-business growth and employment opportunities at Ili-Balkhash Nature Reserve.

In the study, the researchers analyzed scientific literature that revealed Caspian tigers once lived in an area about 800,000 to 900,000 square kilometers in size (between 300,000 and 350,000 square miles), mostly within isolated patches of riparian ecosystems (land along rivers or streams). Generally, two or three tigers occupied an area that covered about 100 square kilometers (about 40 square miles).

Spatial analyses based on remote sensing data indicated that options for Amur tiger introduction are limited in Central Asia. But at least two habitat patches are potentially suitable for tiger re-establishment, both in Kazakhstan. When the researchers considered current land use and the low density of the local human population, they found the most promising site is the Ili River delta and adjacent southern coast of Balkhash Lake. The river flows from northwestern China into southeastern Kazakhstan; it drains into Balkhash Lake, the 15th largest lake in the world. 

The team identified about 7,000 square kilometers (about 2,700 square miles) of suitable habitat. Population models for animals that tigers typically prey on -- wild boar, Bukhara deer and roe deer -- suggest the area could support a population of between 64 and 98 tigers within 50 years if 40 to 55 tigers are introduced. 

The Amur tiger is apparently the only subspecies that has significantly increased in number in the last 65 years. Scientists estimate some 520 to 540 still live in the wild. Moving some of them from the Russian Far East to the Ili River delta could be enough to eventually establish a wild population in 50 years, and would not harm the Russian population, the study says.

Around the world, similar relocation programs have worked for cat populations. The study says: "... case studies suggest high adaptive potential of big cats to novel environments. We know of no large cat translocation programs that failed strictly due to maladaptation of source population to environment of release."