Study Shows Large Carnivore Numbers and Range Declining Worldwide

New research co-written by University of Montana scientists finds steep declines in the worldwide populations and habitat range of 31 large carnivore species. The analysis, published Jan. 9 in Science, shows that 77 percent of the studied species – including tiger, lion, dingo and puma – are decreasing in number.

Associate Professor of ungulate habitat Mark Hebblewhite and John J. Craighead Chair and Professor of Wildlife Conservation Joel Berger, both of the UM College of Forestry and Conservation, co-wrote the study with scientists from Oregon State University, the University of California, Yellowstone National Park, University of Washington, Yale University and researchers in Australia, Italy and Sweden.

The study shows that 17 of the species occupy less than half their normal habitat range. These changes have serious environmental consequences, the authors argue.

Large carnivores are vulnerable to extinction because of their low population densities and their need to roam widely to search for food. These animals are essential to the health of an ecosystem and also provide social and economic benefits for humans.

“Ecosystems depend on large carnivores to control herbivores like deer and populations of smaller carnivores,” Hebblewhite said. “We suggest that losing a population of large carnivore doesn’t just impact that species, but an entire landscape.”

Further declines in the populations of these large carnivores will lead to changes in plant species diversity, biomass and productivity. These vegetation changes will have a wide-ranging influence on other species. Carnivore losses also will impact wildlife disease dynamics, wildfire and carbon sequestration.

Hebblewhite points to several success stories, like the reintroduction of gray wolves to Yellowstone National Park, potential delisting of grizzly bears in the Northern Rockies and the Global Tiger Initiative, to demonstrate that reintroducing and recovering carnivores has many benefits.

In Yellowstone National Park, the return of wolves has contributed to aspen and willow restoration, stabilized carrion availability for scavengers like grizzly bears and magpies, and has increased carbon storage by allowing plants to flourish.

But beyond the large carnivore conservation successes of the Northern Rockies, carnivore populations are declining worldwide, especially in Asia and Africa. These declines are mostly due to habitat loss, overhunting and trade of endangered wildlife parts.

“We haven’t yet untangled all the ways in which these large carnivore population declines will play out in the future – but we know they will have profound ecosystem impacts,” Berger said.

Hebblewhite and Berger agree that lessons learned from carnivore reintroduction in the Northern Rockies can serve as a model to the rest of the world. At UM, training international students in large carnivore conservation is a key focus.

Wildlife biology doctoral student Tshering Tempa currently applies some of these advances in carnivore science and conservation to Bengal tigers in his home country of Bhutan.

“Conservation has to be underpinned by sound science,” Tempa said. “In Bhutan, there is a real chance of ensuring that large carnivores and their prey persist perpetually. I am applying the skills I have learned at UM to contribute toward this.”

With looming threats to global distributions of large carnivores, Hebblewhite concludes that more science is needed to better understand all the benefits of every large carnivore species, which human activities are most in conflict with large carnivores, and what management activities will have the most impact on sustaining large carnivore populations.

Paper predicts a future without carnivores would be truly scary

A fascinating paper released today from a team of leading scientists, including Dr. Joel Berger of the Wildlife Conservation Society and University of Montana, reports on the current status of large carnivores and the ecological roles they play in regulating ecosystems worldwide, and finds that a world without these species is certainly scarier than a world with them.

From sea otters that keep sea urchins in check and enable the rise of kelp beds thus increasing the productivity in inland coastal areas to pumas that mediate the browsing of mule deer and thus enhance the growth and reproduction of woody plants, the scientists profile seven of the 31 largest species of the order Carnivora and their well-studied ecological effects.

The paper, "Status and Ecological Effects of the World's Largest Carnivores," appears in the January 10, 2014 issue of the journal, Science. More than 100 published studies were reviewed to offer a comprehensive look at the state of carnivores and their impacts on the world today.

WCS Executive Vice President of Conservation and Science John Robinson said, "This important paper explores how carnivores regulate the structure and functioning of ecosystems and what happens when they are lost. For many people, it will be an eye-opener and hopefully bring about a change in attitudes and a deeper appreciation of these key species. Around the world, WCS continues to work to preserve the ecosystems that are vital to carnivores and to understand the critical benefits they provide to both wildlife and people."

Among their many impacts, carnivores are a benefit to ecotourism. Yellowstone National Park's restored wolf population, for example, brings in tens of millions of dollars in tourist revenue each year. And when wolves are absent, the effect on natural selection is dramatic. "In Badlands National Park, we have observed bison born with deformed hooves or portions of their legs missing," said WCS Conservation Scientist and author of The Better to Eat You With, Joel Berger. "Historically, these bison would have been selected out for predation by wolves, contributing to the overall health of the herd. Today, without wolves, these bison survive and reproduce. This is not the way healthy ecosystems are maintained."

The ecological services provided by carnivores are multifarious. Carnivores control herbivores to the relief of plants, mitigate global warming, enhance biodiversity, restore rivers and streams, and regulate wildlife disease and livestock disease spillover.

However, many of the largest carnivores are listed as threatened on the International Union for the Conservation of Nature (IUCN) Red List, and most are still declining in number. These 'top or apex predators' have one great competitor: humans.

The authors note that "large-carnivore population declines are typically precipitated by multiple, and sometimes concurrent, human threats including habitat loss and degradation, persecution, utilization (such as for traditional medicine, trophy hunting or furs), and depletion of prey."

Oregon State University professor and lead author of the paper, William J. Ripple said, "Globally, the ranges of carnivores are collapsing and many of these species are at risk of either local or complete extinction. It is ironic that large carnivores are disappearing just as we are learning about their important ecological and economic effects."

Looking to the future, the scientists expect that the loss of apex predators will bring degradation to ecosystems that include reductions in plant diversity, biomass and productivity as well as wide-ranging impacts to other species. Greater rates of herbivory and concurrent decline of plant species may hasten global warming and desertification.

Critical to living with carnivores, the scientists conclude, is an understanding of the benefits they provide and where human/predator conflicts arise. Linking policy issues facing people such as population growth, meat consumption and exploitation of wild prey, livestock production, greenhouse gas emissions, food security, deforestation and desertification, and water quality/quantity with carnivore conservation is a necessary step toward coexistence.

Plan to delist gray wolf endangers other threatened species, researchers find

The federal government's proposal to discontinue protection for the gray wolf across the United States could have the unintended consequence of endangering other species, researchers say.

As written, scientists assert, the proposed rule would set a precedent allowing the U.S. Fish and Wildlife Service (FWS) to declare habitat unsuitable for an endangered animal because a threat exists on the land – the exact opposite of the service's mandate to impose regulations that reduce threats against imperiled species.

The FWS has "conflated threats with habitat suitability" by stating that U.S. land currently unoccupied by wolves – most of the country that historically served as wolf habitat – is now unsuitable because humans living in those regions won't tolerate the animals, the lead scientist said. This claim runs counter to existing research, which the service did not cite in its explanation of the rule.

"The Fish and Wildlife Service is supposed to detail what the threats are and if they're substantial enough, they're supposed to list a species and put in place policies to mitigate the threats," said Jeremy Bruskotter, associate professor in The Ohio State University's School of Environment and Natural Resources and lead author of the paper.

"Here, they're saying that they recognize the threat of human intolerance and instead of mitigating the threat, they're just going to say the land is unsuitable."

Were this rule to stand, he said, "Anytime the U.S. Fish and Wildlife Service finds that something is in the way of a species' recovery, they can just say the habitat is unsuitable for the species and disregard the threat altogether."

FWS proposed removing the gray wolf (Canis lupus) from the list of threatened and endangered species in June. The rule covers most of the continental United States where wolves historically existed, before being exterminated by people in the late 19th and early 20th centuries. Public comments closed Dec. 17, and will be analyzed and considered before the service issues a final rule.

The critique is published online in the journal Conservation Letters.

Congress passed the Endangered Species Act in 1973. The act expanded on previous legislation by providing for the protection of any species in danger of or threatened with extinction throughout all or a significant portion of its range.

The act's language is critical to what follows: In determining whether a species has recovered, the law requires FWS to declare it is no longer endangered in all or a "significant portion of its range." The gray wolf has recovered in the northern Rockies and upper Great Lakes.

The proposed rule, however, discounts the other 85 percent of the wolf's historic range, which stretches across northern states from the west coast through New England and as far east as mid-Texas in the southern half of the country.

"So what the service is saying is that wolves are going to be called recovered in most of the United States despite the fact that very few wolves live outside these two recovered areas," Bruskotter said. "Wherever they are now, that's their range – which means taking the historic and geographic component out of the listing process."

He and colleagues suggest that this practice not only disregards the law, but "specifically creates incentive to destroy habitat in advance of a listing and do things that aren't good for endangered species."

The law also requires the service to consider the "best available science" in assessing whether threats have eased and a species is recovered. Instead of citing the dozens of studies that suggest human support for wolf restoration is high, the service simply ignored this research and claimed that these areas are unsuitable because of human intolerance. When federal protection is lifted, species management falls to the states.

"That process is not the best available science," Bruskotter said.

Bruskotter acknowledged that FWS is under enormous pressure from the opposing sides of a highly contentious fight about wolves: hunters and livestock producers on one side and wildlife advocates on the other. But that pressure doesn't relieve the service of its duty to act on behalf of endangered species as the law requires, he said.

"The law is supposed to help the protected species, not just describe the threats to that species. But to construct this delisting rule, they've had to interpret policy and science in every case in a way that either disregards threats to wolves, or treats them as insurmountable," he said. "They're doing the opposite of what the act requires."

Climate change has silver lining for grizzlies

Global warming and forest disturbances may have a silver lining for threatened species of grizzly bears in Alberta, Canada.

In a 10-year study that monitored 112 bears in Alberta's Rocky Mountain region, University of Alberta biologist Scott Nielsen and his colleagues found that warmer temperatures and easier access to food associated with forest disturbances helped the grizzlies to build more body fat, known to increase the chances of successful reproduction for mothers.

The resulting 'silver spoon effect' shows that bears born into these favourable conditions have a head-start in life, said Nielsen, an assistant professor in the U of A Department of Renewable Resources.

"Understanding variations in body size helps us understand what limits grizzly populations," Nielsen said. "We get clues about the environments that most suit grizzlies by examining basic health measures such as body size. A simple rule is, the fatter the bear, the better. Certain environments promote fatter bears.

The findings, published in BMC Ecology, may help influence forest harvest designs to enhance habitat for the Alberta grizzly, which is classed by the Alberta government as a threatened species. Currently there are only about 750 of the bears in the province, half of them adults.

In years when warmer temperatures and less late winter snow brought on earlier spring conditions, the body size of bears as adults was larger. Smaller bears were found in colder and less productive environments or years that were abnormally cool.

"We hypothesize that warmer temperatures in this ecosystem, especially during late winter and spring, may not be such a bad thing for grizzlies," Nielsen said, noting that historically the range for the bears once extended as far south as Mexico and persists today even in the deserts of Mongolia. "That suggests the species won't likely be limited by rising temperatures which would lengthen the growing season and the time needed to fatten prior to hibernation."

As well, bears that used disturbed forest habitats containing a wide variety of stand ages were healthier, Nielsen said.

"The diversity of stand ages in the landscape has a positive influence on body condition because bears are better able to access a wide range of food sources."

Coyote more likely to make a meal out of moose than we thought: Study

It has long been believed that coyotes were incapable of taking down an adult moose, but researchers have recently discovered that eastern coyotes and coyote × wolf hybrids (canids) have preyed on adult moose in central Ontario. Their findings were published today in the Canadian Journal of Zoology.

Researchers Dr. John Benson, a PhD student in the Environmental and Life Sciences Graduate Program at Trent University when he conducted the research, and Dr. Brent Patterson, a research scientist with the Ontario Ministry of Natural Resources in Peterborough, documented instances where packs of eastern coyotes and coyote × wolf hybrids (canids) were found to have killed moose.

Their study involved live capture of eastern coyotes and eastern coyote × eastern wolf hybrids to deploy Global Positioning System (GPS) radio-collars and take blood samples for DNA analysis. The GPS collars delivered highly accurate locations of the study animals (via satellites or cell towers) so the researchers were able to visit these locations during winter to investigate their activities and document predation patterns. The DNA analysis allowed them to determine whether the animals were coyotes, wolves, or coyote × wolf hybrids.

In the study, four canid packs ranging in size from two to five animals were found to have killed moose. The researchers obtained two accurate ages from moose that were killed by coyotes and/or hybrids: One was very old (20 years) and one was young (20 months). It is believed that younger and older adult moose are probably more vulnerable due to inexperience and deteriorating body condition, respectively.

“Coyotes and coyote × wolf hybrids probably prey on moose opportunistically and only when circumstances are favorable. For instance, when snow is deep and a hard crust forms on top this impedes the ability of moose to travel and gives the lighter coyotes and hybrids an advantage because they can travel on top of the snow,” explained Dr. Benson.

“Additionally, we noticed that some of the moose killed by coyotes and hybrids were on steep slopes that may have slowed the moose and created unstable footing. We also found that some of the moose were killed in areas where medium-sized trees were moderately dense, which may have prevented moose from swinging around quickly to fend off predators attacking from the rear or side.”

“Killing of adult moose by eastern coyotes and coyote × wolf hybrids appears to be relatively rare and probably does not pose a threat to moose populations in central Ontario. However, from the perspective of a pack of coyotes or hybrids, killing even a single moose during a winter is very beneficial and goes a long way towards helping them meet their energetic demands. For instance, a pack of two eastern coyotes spent some or all of 18 days feeding on a moose that they killed.”

The authors do not believe the viability of moose populations in central Ontario is negatively affected by this predation, as recent studies have shown that populations in WMU49 and nearby Algonquin Provincial Park are increasing and that both adult and calf moose survival is relatively high.

This research was a collaborative project between the Ontario Ministry of Natural Resources and Trent University and was conducted in Wildlife Management Unit 49 (WMU49) in central Ontario -- the area between Huntsville, ON and Parry Sound, ON.

The article “Moose predation by eastern coyotes and coyote × wolf hybrids” by John F. Benson and Brent R. Patterson is published today in the Canadian Journal of Zoology.

Of bears and berries: Return of wolves aids grizzly bears in Yellowstone

A new study suggests that the return of wolves to Yellowstone National Park is beginning to bring back a key part of the diet of grizzly bears that has been missing for much of the past century – berries that help bears put on fat before going into hibernation.

It's one of the first reports to identify the interactions between these large, important predators, based on complex ecological processes. It was published today by scientists from Oregon State University and Washington State University in the Journal of Animal Ecology.

The researchers found that the level of berries consumed by Yellowstone grizzlies is significantly higher now that shrubs are starting to recover following the re-introduction of wolves, which have reduced over-browsing by elk herds. The berry bushes also produce flowers of value to pollinators like butterflies, insects and hummingbirds; food for other small and large mammals; and special benefits to birds.

The report said that berries may be sufficiently important to grizzly bear diet and health that they could be considered in legal disputes – as is white pine nut availability now - about whether or not to change the "threatened" status of grizzly bears under the Endangered Species Act.

"Wild fruit is typically an important part of grizzly bear diet, especially in late summer when they are trying to gain weight as rapidly as possible before winter hibernation," said William Ripple, a professor in the OSU Department of Forest Ecosystems and Society, and lead author on the article. "Berries are one part of a diverse food source that aids bear survival and reproduction, and at certain times of the year can be more than half their diet in many places in North America."

When wolves were removed from Yellowstone early in the 1900s, increased browsing by elk herds caused the demise of young aspen and willow trees – a favorite food – along with many berry-producing shrubs and tall, herbaceous plants. The recovery of those trees and other food sources since the re-introduction of wolves in the 1990s has had a profound impact on the Yellowstone ecosystem, researchers say, even though it's still in the very early stages.





IMAGE: This is a grizzly bear in Yellowstone National Park.
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"Studies like this also point to the need for an ecologically effective number of wolves," said co-author Robert Beschta, an OSU professor emeritus. "As we learn more about the cascading effects they have on ecosystems, the issue may be more than having just enough individual wolves so they can survive as a species. In some situations, we may wish to consider the numbers necessary to help control overbrowsing, allow tree and shrub recovery, and restore ecosystem health."

As wolves help reduce elk numbers in Yellowstone and allow tree and shrub recovery, researchers said, this improves the diet and health of grizzly bears. In turn, a healthy grizzly bear population provides a second avenue of control on wild ungulates, especially on newborns in the spring time.

Yellowstone has a wide variety of nutritious berries – serviceberry, chokecherry, buffaloberry, twinberry, huckleberry and others – that are highly palatable to bears. These shrubs are also eaten by elk and thus likely declined as elk populations grew over time. With the return of wolves, the new study found the percentage of fruit in grizzly bear scat in recent years almost doubled during August.

Because the abundant elk have been an important food for Yellowstone grizzly bears for the past half-century, the increased supply of berries may help offset the reduced availability of elk in the bears' diet in recent years. More research is needed regarding the effects of wolves on plants and animals consumed by grizzly bears.

There is precedent for high levels of ungulate herbivory causing problems for grizzly bears, who are omnivores that eat both plants and animals. Before going extinct in the American Southwest by the early 1900s, grizzly bear diets shifted toward livestock depredation, the report noted, because of lack of plant-based food caused by livestock overgrazing. And, in the absence of wolves, black bears went extinct on Anticosti Island in Canada after over-browsing of berry shrubs by introduced while-tailed deer.

Increases in berry production in Yellowstone may also provide a buffer against other ecosystem shifts, the researchers noted – whitebark pine nut production, a favored bear food, may be facing pressure from climate change. Grizzly bear survival declined during years of low nut production.

Livestock grazing in grizzly bear habitat adjacent to the national park, and bison herbivory in the park, likely also contribute to high foraging pressure on shrubs and forbs, the report said. In addition to eliminating wolf-livestock conflicts, retiring livestock allotments in the grizzly bear recovery zone adjacent to Yellowstone could benefit bears through increases in plant foods.

Mercury Pollution Threatens Arctic Foxes

New scientific results show that arctic foxes accumulate dangerous levels of mercury if they live in coastal habitats and feed on prey which lives in the ocean. Researchers from the Leibniz Institute for Zoo and Wildlife Research, Moscow State University and the University of Iceland just published their discovery in the science online journal PLOS ONE.

Mercury is usually transferred across the food chain, so the researchers checked which items were the main source of food and measured mercury levels in the main prey of Arctic foxes.

The scientists compared three fox populations in different environments. Foxes on the small Russian Commander Island of Mednyi fed almost exclusively on sea birds, with some foxes eating seal carcasses. In Iceland, foxes living on the coast ate sea birds whereas those living inland ate non-marine birds and rodents.

In all three environments different levels of mercury were present in their hair. Foxes living in coastal habitats such as Iceland and Mednyi Island exhibited high levels of mercury.

What does this mean for the foxes? Using museum skin samples from the Commander Islands, the researchers could show that the foxes suffered exposure to mercury for a long time. The researchers confirmed that the source of contamination was their food, as they measured high mercury levels in the prey of foxes such as seals and sea birds.

However, the inland Arctic fox populations of Iceland had low mercury levels. Thus, living inland and eating non-marine birds and rodents instead of eating prey that feeds from the sea protected the inland foxes from mercury exposure. This may have health and conservation implications. The Mednyi Island foxes are almost an opposite example to the inland Icelandic fox population. They live on a small island with no rodents or alternative food source to seals or sea birds. They suffered a tremendous population crash and while the population is currently stable, it is very small and juvenile foxes in particular show high mortality rates. Foxes of all ages exhibit low body weight and have poor coat condition.

"When going into this project we thought that an introduced pathogen would explain the poor condition of the foxes and their high mortality but after extensive screening, we did not find anything," says Alex Greenwood, principal investigator of the study. Instead, the researchers began to suspect that something else was at play. "If pathogens were not the cause, we thought perhaps pollutants could be involved. We thought of mercury because it has been reported in high concentration in other Arctic vertebrates also in remote areas and mercury intoxication is known to increase mortality in mammals. As mercury can have negative effects on overall health, particularly in young individuals, and as we knew that Mednyi foxes were exclusively feeding on potentially contaminated sources, we wanted to see whether contamination with mercury depended on feeding ecology and hence might have been the crucial factor for the population decline on Mednyi Island," comments Gabriele Treu, one of the lead authors of the study. As it turned out, the observed high mercury demonstrated a tight association with feeding ecology and geographical distribution of the foxes.

In terms of conservation and long term population health for the entire arctic food chain of carnivores, mercury pollution must be stopped.