Wolves in a Tangled Bank

by Cristina Eisenberg

The wolves’ return to Yellowstone and the subsequent recovery of plants that elk had been eating to death in their absence has become one the most popularized and beloved ecological tales. By the 1920s humans had misguidedly wiped out most of the wolves in North America, thinking that the only good wolf was a dead one. Without wolves preying on them, elk and deer (also calledungulates) exploded in number. Burgeoning ungulate populations ravaged plant communities, including aspen forests. Decades later, the wolves we reintroduced in Yellowstone hit the ground running, rapidly sending their ecological effects rippling throughout the region, restoring this ecosystem from top to bottom. Yet today some scientists caution that this story is more myth than fact because nature isn’t so simple.

For decades scientists have been investigating the ecological role of wolves. In his 1940s game surveys, Aldo Leopold found ungulates wiping out vegetation wherever wolves had been removed. He concluded that by controlling ungulates, wolves could restore plant communities and create healthier habitat for other species, such as birds.

Since Leopold’s time, many scientists have studied food web relationships between top predators and their prey—called trophic cascades. In the 1960s and 1970s Robert Paine, working with sea stars, and James Estes, working with sea otters, showed that ecosystems without top predators begin to unravel. John Terborgh called the ensuing rampant species extinctions an “ecological meltdown.” Paine created the metaphorical termkeystone species to refer to top predators and noted that when you remove the keystone, arches and ecosystems collapse. Over the years ecologists found trophic cascades—also called top-down effects—ubiquitous from coral reefs to prairies to polar regions. However, William Murdoch and others have maintained that sunlight and moisture, which make plants grow, drive ecosystem processes from the bottom-up, making predators relatively unimportant. The Yellowstone wolf reintroduction provided the perfect setting to test these contrasting perspectives.

In the mid-1800s in his book The Origin of Species, Charles Darwin presciently described nature as a “tangled bank.” Nature’s complexity results from myriad species and their relationships with other species and all the things that can possibly affect them individually and collectively, such as disease, disturbance, and competition for food. Science works incrementally, taking us ever deeper into nature’s tangled bank as we investigate ecological questions. Each study answers some questions and begets new ones. Sometimes we find contradictory results. Learning how nature works requires what Leopold called “deep-digging research” in which we keep searching for answers amid the clues nature gives us, such as the bitten-off stem of an aspen next to a stream where there are no wolves.

waterton lakes

Trophic cascades science that focuses on wolf effects is still in its infancy, with huge knowledge gaps. For example, we’ve linked wolves to strong effects that cascade down through multiple food web levels. However, we’re just starting to parse how context can influence these effects. Some Yellowstone studies have found that wolves have powerful indirect effects on the plants that elk eat, such as aspens, due to fear of predation. With wolves around, elk have to keep moving to stay alive, which reduces browsing pressure. Conversely, a growing body of studies are finding no wolf effect—that aspens in places with wolves aren’t growing differently than those where predation risk is low. Other studies have found that wolf predation risk doesn’t affect elk feeding behavior. In my own research I’ve found that wolves need another keystone force—fire—to most effectively drive trophic cascades. With wolves and fire present, elk herbivory drops, aspens thrive, and biodiversity soars due to the healthy habitat created by young, vigorously growing aspen.

aspen, Glacier National Park

It’s human nature to try to find simple solutions. Today we are grappling with monumental environmental problems such as climate change and habitat fragmentation. Due to the wolf’s iconic status and our need to fix broken ecosystems, the environmental community and the media have run with the science that shows a strong wolf effect. This has inspired other scientists to prove that ecosystems are more complex than that. These dissenting studies demonstrate that the wolf dwells in a tangled bank, working alongside many other ecological forces.

Tangled banks seldom yield simple answers. However, arguing about what exactly carnivores do ecologically and why we need them is fiddling while Rome burns. Large, meat-eating animals improve the health of plant communities and provide food subsidies for the many species that scavenge on their kills. A system with wolves in it is far richer than one without and can support many more grizzly bears, coyotes, wolverines, and eagles. There are things we don’t know and disagreements about what we do know. But given the accelerated human-caused extinctions we are experiencing today, a precautionary approach to creating healthier ecosystems means conserving large carnivores.

Beyond empiricism, scientists often operate based on instinct. Instinct led Darwin to dig more deeply into species adaptation and Leopold to doggedly delve into the effects of predator removal. For many of us who conduct trophic cascades science, our instincts are telling us that wolves should be conserved in as high a number in as many places as possible, due to the invaluable benefits they can bring to ecosystems. To do anything other than conserve wolves would be foolish, given all we’ve learned thus far.

Source: http://ipfieldnotes.org/wolves-in-a-tangled-bank/

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Lion takes on crocodile in war over hippo

THIS is the amazing moment a lion fought off the snapping jaws of a crocodile so it could feed on a dead hippo

The incredible battle was caught on camera by Richard Chew

The incredible battle was caught on camera by Richard Chew [CATERS/RICHARD CHEW]

The pictures were taken in the Maasi Mara nature reserve, in Kenya and show hungry lion braving a crocodile-infested river to get to an upside down hippo, which had died overnight of natural causes.

The incident was witnessed and captured on camera by Richard Chew, an IT manager from San Francisco, USA who was on holiday with his wife.

Semi- professional photographer Richard has travelled the world taking pictures but said it was a really unique moment.

He said: “It was such an amazing moment in wildlife and our Kenyan guide Abdul has never seen anything like it before.

Lion

The pictures were taken in the Maasi Mara nature reserve, in Kenya [CATERS/RICHARD CHEW]

The lion takes a mighty swing at the croc’s snapping jaws [CATERS/RICHARD CHEW]

The whole river was infested with crocodiles [CATERS/RICHARD CHEW ]

The lion defiantly snarls at the croc [CATERS/RICHARD CHEW]

“Two lions spotted the hippo at first but couldn’t reach it as they were on the wrong side of the river.

“The lions left in search of other prey and we went to explore a different area.” But when Richard returned to the same spot at the end of the day, the two lions had managed to get to the other side and were battling with 15 crocodiles for the free meal.

“The lions were really showing no fear. The river was full of crocodiles who were wanting a piece of the hippo but the lions were putting up a good fight.

“It was amazing to watch the wildlife food chain in action.”

Source: http://www.express.co.uk/news/nature/466503/Battle-of-the-beasts-Incredible-moment-a-lion-takes-on-a-crocodile-in-war-over-a-hippo

Overkill – trophy hunting slams BC’s Grizzly bears

In BC, Canada, a surge in trophy hunting may be reducing Grizzly bear populations, writes Anna Taylor. A new study finds evidence of serious Grizzly bear ‘overkill’ from multiple causes of mortality – in which trophy hunting is a big contributor.

In one area, trophy hunters killed 24 more grizzlies than the quota allowed, and overhunting was particularly prevalent for female bears that are critical for a sustainable population.

The British Columbia Government claims that the quotas they set for the number of Grizzly bears allowed to be killed each year ensure that hunting practices are sustainable.

But a new study into the management of Grizzly bears in BC, published in the open-access journalPLoS ONE, finds that so-called ‘overkills’ occurred in half the Grizzly bear populations.

The findings are also relevant to the USA andproposals to strip Grizzly bears of federal protection under the Endangered Species Act.

Worrying discoveries

Scientists set out to test the BC Government’s claim and made some worrying discoveries. Kyle Artelle, from Simon Fraser University and lead author of the study, explains:

“We tested how well managers were able to maintain grizzly bear kill rates below limits their own biologists have deemed sustainable.

“This assessment was straightforward – for a given population and across three management periods we simply compared the number of bears the province said could sustainably die (‘mortality limits’) by human-caused kills to the number that actually died.”

Too many unknowns

To do this his team looked at three key quantities that carry considerable uncertainty: population estimates; population growth rates; and the number of unreported human-caused bears deaths, including poaching kills.

The population growth rates are key in this, says Artelle – also a wildlife scientist with the Raincoast Conservation Foundation – because they are used to estimate how many bears can be killed in a given population without causing declines.

“You can imagine how these might contribute to undetected overkills – for instance if you assume a population is a given size and set your hunting quotas accordingly, if it turns out the population is actually smaller, then the hunting quotas you set would have been too high.

“We addressed this quantitatively and found that, based on unaddressed uncertainty, overkill rate might indeed be considerably higher than previously assumed.”

They found that overkills – defined as taking place when the number of kills exceeds the mortality limits that are set by the government – occurred in half of the populations that are open to hunting. Artelle says that hunting is adding to the other problems faced by the bears:

“Although these were caused by a mix of hunting and other human-caused kills – road and rail accidents, self-defence kills, ‘problem bear’ kills and so on – we found that almost all overkills could have been prevented by reducing or eliminating the hunt.”

Hunting quotas breached

In one area, trophy hunters killed 24 more grizzlies than the quota allowed, and overhunting was particularly prevalent for female bears that are critical for a sustainable population. This shows that guidelines that encourage hunters to avoid females are clearly inadequate.

There is considerable uncertainty about Grizzly bear population growth rates and unreported human kills, as well as how hunting affects other aspects of Grizzly bear biology such as genetics, social interactions and evolutionary processes.

It is also uncertain exactly how long different populations take to recover from population declines, the effects of changes to food availability and cumulative effects of other threats to grizzlies, logging and development for example.

Population uncertainties

Of great concern is the uncertainty of total population size. The current best estimate is 15,000 Grizzly bears in British Columbia – however the figure could be higher or lower.

It appears that few on-the-ground surveys have actually been done, with the estimate being largely based on computer modelling or expert opinion.

The government claims the management of the Grizzly bear hunt is based on “sound science” – yet Jessie Housty, tribal councillor of the Heiltsuk First Nation, doubts this.

On the Central BC Coast, where government sanctioned trophy hunting is at odds with tribal law that prohibits it, she emphasises that no inventories have been conducted.

“How could the government possibly have a solid understanding of these bears they condemn to the hunt without setting foot in our Territory?”

These are known unknowns

The government is failing to take all of these uncertainties into account when setting hunting limits, says Artelle.

“This uncertainty in and of itself is not inherently a problem – uncertainty exists in all management. The problem in BC Grizzly bear management is that the uncertainty is simply ignored.

“Although the government maintains their targets are conservative, a simple comparison between their own limits and their own records of kill rates show that is clearly not the case.”

Dr Chris Darimont, science director at the Raincoast Conservation Foundation (RCF) and a co-author of the study, is worried:

“Ignoring uncertainty – in dimensions such as true population size – is like playing Russian Roulette. As the history of wildlife management has shown repeatedly, the consequences of not accounting for the unknowns are grave.”

The RCF has raised concerns about BC’s Grizzly trophy hunt in the past. The European Union banned the import of BC Grizzly bear parts in 2002 due to their concerns over sustainability.

Hunting quotas should be halved – or banned

There is one very simple solution to the problem of overkills – reduce the hunt.

“If the government wants to ensure mortality levels are kept below limits set by their own biologists their targets need to be reduced,” says Artelle.

The scientists found that the BC government could reduce the risk to their Grizzly bears by cutting its hunting quotas by at least a half, which would reduce the probability of overkills by an average of 85%.

British Columbia is one of the last strongholds for North American Grizzly bears. Since European colonization, they have lost half of their continental range, and even in BC around one third of populations have either gone extinct or are currently threatened.

Multiple threats

“We know that grizzly bears are highly vulnerable to management error – because of their reproductive biology populations that suffer declines often don’t recover, or take considerable time to do so”, said Artelle.

“And at a provincial level the trend is not promising – through recent decades we have seen an overall trend of more and more populations gaining threatened status or disappearing altogether.

“We also know that grizzlies face a variety of other threats that are not yet fully understood, from declining salmon stocks on BC’s coast, white-bark pine failures inland, and climate change and development pressures throughout the province.

“Given the considerable threats many argue that grizzly managers should err on the side of caution, which our analyses strongly suggest they are not currently doing.”

Yet hunting increased

Despite these threats to the Grizzlies, during the study period, between 2001 and 2011, hunting mortality actually increased. For this reason, many people in BC are in favour of the complete elimination of trophy hunting in their province.

The Coastal First Nations, an alliance of nine BC First Nations, have called upon Premier Christy Clark to end the hunt by organizing a petition.

They have banned trophy hunting in their expansive traditional territories in BC’s Great Bear Rainforest because they believe that the government is risking the long-term survival of the bears.

Jessie Housty says: “Our responsibility as First Nations is to step into that regulatory vacuum, and protect the bears in our territories.”

80% of BC residents oppose the grizzly hunt

Environmentalists are also strongly opposed to the hunt, as are 80% of British Columbians, according to a recent McAllister Research Poll.

Throughout North America it is being recognised that hunting must be stopped in order to protect Grizzly bears. Yet in BC, despite widespread disapproval and bad science, the hunt looks set to continue. Artelle concludes:

“In other jurisdictions, such as the province of Alberta and the Kenai peninsula in Alaska, hunts have been closed due to sustainability concerns. In BC there has been a trend through time of a growing number of populations gaining threatened status.

“Whereas history from within and beyond the province suggests cautious management might be warranted, our research found that current management entails considerable risk, suggesting that continued overkills are likely.”

Anna Taylor is a freelance science journalist, specialising in environmental issues and new discoveries in conservation biology. She posts regular blogs on Conservation Jobs.

Anna has also worked in conservation and conservation research for RSPB and other employers in the UK, Africa and the Amazon. She has a BSc in Conservation Biology and a Masters in Ecology and Environmental Biology.

Source: http://www.theecologist.org/News/news_analysis/2271852/overkill_trophy_hunting_slams_bcs_grizzly_bears.html

BC grizzly bears are being over hunted, putting the future of the population at risk, say the authors of a new study released today in the scientific journal PLOS ONE.

Researchers from the University of Victoria, Simon Fraser University and Raincoast Conservation Foundation show in their report that there are serious shortfalls with the management of the grizzly bear hunt in BC.

Researchers found large discrepancies between the upper limit to kills set by the provincial government and the number of grizzly bears killed.

“In half of BC’s remaining grizzly populations, our audit detected overkills, and almost all were associated with excessive trophy hunting,” says Dr. Chris Darimont, UVic geography professor, Raincoast science director and the study’s co-author. “The pattern of overkills we documented surprised and alarmed us, especially for female grizzly bears, which are the reproductive powerhouses of populations.”

BC represents one of the last strongholds for grizzly bears, which have lost about half of their historical range in North America since European colonization.

The report, Confronting Uncertainty in Wildlife Management: Performance of Grizzly Bear Management, is co-authored by Kyle Artelle (lead) and Sean Anderson, SFU PhD students; SFU professors Dr. John Reynolds and Dr. Andrew Cooper, and Dr. Paul Paquet, Raincoast senior scientist and adjunct UVic geography professor.

The report is available at PLOS ONE http://dx.plos.org/10.1371/journal.pone.0078041

The world’s top predators are in decline, and it’s hurting us too

Humans have an innate fear of large predators, and with good reason. Nobody wants to be a shark or a lion’s next meal.

But new research in the journal Science shows that our inability to live with these animals is putting their survival in great danger, and doing untold damage to the environment.

Through modifying the habitats of large predators or killing predators more directly, we are greatly compromising the ecosystems that they help to keep in balance — free of charge. In turn this environmental degradation creates many problems that have severe consequences for humans.

 

We ain’t lion, this predator stuff is a big deal. Flickr/Derek Keats
Click to enlarge

 

Top dogs (and cats) under threat

For the first time, a team of researchers from the United States, Australia, Italy, and Sweden, and led by Professor Bill Ripple at Oregon State University, have analysed the effects of threats such as habitat loss, human persecution and reduced prey on the world’s 31 largest mammalian carnivores.

The species studied include lions, tigers, African wild dogs, leopards, cheetahs, wolves, lynx, otters, bears, hyenas and dingoes. Together they span all continents except Antarctica.

Alarmingly, more than three quarters of the 31 large carnivores are in decline, and 17 species occupy less than half of their historical distributions. The Red Wolf in the southeastern United States is now found in less than 1% of its historical range, and theEthiopian Wolf in just 2%.

Hotspots of carnivore decline are southeast Asia, southern and East Africa, and the Amazon, where several large carnivores are declining. And in the developed world there are now few places where large carnivores remain.

 

In Australia, dingoes help keep introduced predators at bay. Flickr/Ars Electronica
Click to enlarge

 

Aside from the intrinsic tragedy of losing any species, what should perhaps concern us even more is that we are only just beginning to understand and appreciate just how important large predators are to maintaining healthy ecosystems, and our dependence on the ecosystem services they deliver.

Ripple effect

Seven carnivore species in particular have been shown to have profound effects on the environment and cause what is known as “trophic cascades”. A trophic cascade is a ripple effect, where one species’ influence spreads through multiple levels of a food web.

Species for which this effect is most well-known are African lions, leopards, Eurasian lynx, cougars, gray wolves, sea otters and dingoes.

 

It’s hard being a VIP (very important predator). Flickr/Mike Baird
Click to enlarge

 

In Australia dingoes greatly reduce kangaroo and red fox numbers, which in turn reduces grazing of vegetation and predation of native animals, helping to conserve and protect biodiversity.

In coastal North America, sea otters keep sea urchin numbers in check, which helps maintain kelp forests and benefits other marine species dependent on this habitat. But in this case otters might also offer a defence against climate change, as healthy kelp forests can grow rapidly and store large amounts of carbon.

And in Africa, a decrease in lions and leopards has coincided with a dramatic increase inOlive Baboons, which threaten farm crops and livestock, and spread intestinal worms. Baboons even impact education, as children have to stay home to defend their farms from raids.

 

Without lions and leopards, there’s no telling what baboons will do. Flickr/JustinJensen
Click to enlarge

 

Clearly predators have far-reaching ecological, economic and social benefits that are grossly underappreciated. There is no doubt predators pose challenges too, such as wolves attacking livestock. But education and new management practices offer ways forward. For instance, we could use guardian animals to protect livestock from predators.

Together we call on governments to end policies and management practices that are responsible for the ongoing persecution and loss of predators from our planet. Western Australia’s new shark plan is an example of management that fails to account for the science of big predators. Instead we need an international initiative that aims to conserve large predators and promote their coexistence with people.

Source: https://theconversation.com/the-worlds-top-predators-are-in-decline-and-its-hurting-us-too-21830

Teaching polar bears to fear humans in order to save them

Churchill in northern Manitoba bills itself as the the polar bear capital of the world and its tourism-based economy depends on it. But as climate change forces the polar bears inland in search of food, attacks on humans are increasing. Can this small community continue to co-exist with the world’s largest land predator? Suzanne Goldenberg reports from Churchill where its bear alert programme uses guns, helicopters and a polar bear jail to manage the the creatures .

This trip was supported by Explore.orgPolar Bears International and Frontiers North

Source: http://www.theguardian.com/environment/video/2013/nov/25/polar-bear-canada-churchill-manitoba-video?CMP=twt_gu

John Terborgh: The Trophic Cascade Regulates Biodiversity

“The Trophic Cascade Regulates Biodiversity”

John Terborgh, Research Professor in the Nicholas School of the Environment and Earth Sciences at Duke University; Director of the Duke University Center for Tropical Conservation

In this presentation, Dr. Terborgh draws on his decades of ecological research in the Neotropics to explain how biological interactions intricately regulate biodiversity. Hypotheses on the maintenance of tropical forest diversity abound, but it is becoming increasingly recognized that interspecific interactions are vital to sustaining the rich diversity the tropics are famous for. Dr. Terborgh offers ecological insights on the regulation of biodiversity and describe how interactions between primary producers, herbivores, and their predators contribute to the richness of tropical forests.

PGE’s interdisciplinary Spring conference, “Conserving More Than Carbon: Valuing Biodiversity in a Changing World”, addressed the current state of knowledge of tropical forest diversity and outlooks for its protection.

Learn more about the conference and the participants at: http://pge.uchicago.edu/biodiversity