Arctic Alaska’s Conservation Conundrum

By  Dr. Joel Berger

The Arctic wind blows hard on the snow-covered plains a few hundred miles southwest of Prudhoe Bay.  It’s eight degrees in the winter chill. Despite global warming, I am still quite cold.  I watch the tracks of the grizzly bear disappear upslope as they narrow toward a newborn calf. Out of my field of vision its mother, a muskoxen – the quintessential land animal of the Arctic – stands guard. But it is no match for the powerful predator looking for its next kill.

Grizzly bears circle in the foreground with musk ox and calf in the distance, Joel Berger © Wildlife Conservation Society

About 3,500 years ago, the last woolly mammoths died on a distant Arctic island in the Chukchi Sea. Muskoxen—mammoths’ shaggy-coated Pleistocene contemporaries—still roam the Alaskan Arctic today. Muskoxen are known to many for their distinctive huddling behavior evolved for defense against predators like grizzly bears and wolves.   Recently this prey-predator relationship has itself become the focus of a discussion on conservation tools and approaches. Continue reading

Polar Bear – POV Cams (Spring 2014)

This video was edited and compiled from raw footage recorded by a camera equipped radio collar that was put on a female polar bear in the Beaufort Sea during April 2014 by the US Geological Survey. The video, which is the first ever from a free-ranging polar bear on Arctic sea ice, shows an interaction with a potential mate, playing with food, and swimming at the water’s surface and under the sea ice. These videos will be used by the US Geological Survey in research to understand polar bear behavior and energetics in an Arctic with declining sea ice. Note: Some creative license has been taken to make this footage easier to follow and understand, including playful language that helps describe the polar bear’s actions.

Location: , Arctic, Beaufort Sea

Date Taken: 4/16/2014

Length: 2:18

Video Producer: Paul Laustsen , USGS Office of Communications and Publishing
Note: This video has been released into the public domain by the U.S. Geological Survey for use in its entirety. Some videos may contain pieces of copyrighted material. If you wish to use a portion of the video for any purpose, other than for resharing/reposting the video in its entirety, please contact the Video Producer/Videographer listed with this video. Please refer to the USGS Copyright section for how to credit this video.

Additional Video Credits:

Produced by USGS
Anthony Pagano: Principal Investigator

Produced by:
Paul Laustsen, Karen Oakley and Stephen M. Wessells

Edited by:
Stephen M. Wessells

Scientific Reviewers:
Todd Atwood
George Durner
Karen Oakley

Mehdi Bakhtiari,
Exeye, LLC, Bristow, VA, USA

USGS Changing Arctic Ecosystems Initiative

Adam Ravetch
Arctic Bear Productions


British Columbia’s hunting quotas are not based on science

Ignacio Yufera/FLPA

Data on grizzly bears in British Columbia are not reliable enough to justify higher hunting quotas, researchers argue.

As the Canadian province of British Columbia prepares to open its annual grizzly-bear hunting season, conservation scientists are protesting the provincial government’s decision to expand the number of animals that can be killed.

British Columbia officials estimate that there are 15,000 grizzlies (Ursos arctos horribilis) in the province, making up roughly one-quarter of the North American population. Although some sub-populations are declining and the species is listed as of “special concern” by some environmental bodies, it is not listed under Canada’s Species at Risk Act, which would afford the bears government protection. Citing the recovery of some sub-populations, the government has opened up previously closed areas to hunting and increased the number of hunting tags for bear kills from about 1,700 to 1,800.

But some researchers say that the original limits for the bear hunt were set too high for sustainable management, and the revised quota could exacerbate that problem.

“Wildlife management wraps itself in science and presents itself as being scientific, but really, when you examine it, it isn’t true,” says Paul Paquet, a biologist at the Raincoast Conservation Foundation in Sidney and the University of Victoria, Canada, and a co-author of a letter in Science this week1 making the complaint.

The allowance is much higher than the actual kill rate — about 300 grizzlies are taken by hunters each year in the province, mainly as trophies — but Paquet and other conservation scientists argue that it is still possible that grizzly bears are dying at a rate that is too high for sub-populations to support.

“They’re going in the wrong direction,” says Kyle Artelle, a conservation ecologist at Simon Fraser University in Burnaby, Canada, and a co-author of the letter.

Last year, Artelle and his colleagues reported that it is common for more bears to die than the government’s stated “maximum allowable mortality rate” of 6% of the population per year2. In more than half of British Columbia’s 42 huntable regions the number of deaths from ‘unnatural causes’, such as road accidents and hunting, exceeded that target for at least one three-year period between 2001–2011. The researchers conclude that reducing the risk of such ‘overkills’ to a low level would require an 81% reduction in the target. “Because these are long-lived, slow-reproducing populations, they don’t necessarily recover from overkill,” says Paquet.

Garth Mowat a biologist with British Columbia’s ministry of forests, lands and natural-resource operations, counters that the 6% target was never meant to be a hard cap. “We choose a conservative number because we know we’re going to go over it occasionally,” he says. “I think [the quotas] are as good as we can do with the data we have, and based on all that, the hunt is sustainable.”

Artelle disagrees that a 6% allowable mortality figure is conservative. He points out that other studies have come up with estimates of 0–5% for British Columbia2. And although a December 2013 study by Mowat and his colleagues concluded that there are about 13,000–14,000 grizzlies in the province3, Paquet says that the number could be as low as 8,000 or higher than 15,000. The data behind such estimates, which come from sources ranging from aerial surveys to traps that snag the hair of passing bears, are often sparse or outdated, he says. “In many cases [the population estimate] will be based on assumptions that are maybe 10 years old. None of this is easy, obviously. But we need to take account of the uncertainties,” he says.

The Convention on International Trade in Endangered Species of Wild Fauna and Flora has banned the import of products from grizzly hunts in British Columbia to Europe, citing the province’s failure to implement a grizzly bear strategy it proposed in 2003, which called for better population assessments, among other things.

“In the United States, there’s recourse to courts,” says Paquet, who notes that there are frequent legal battles over US hunting and the country’s Endangered Species Act. “In Canada there’s essentially no appeal.”

Nature doi:10.1038/nature.2014.14914
  1. Artelle, K. A., Reynolds, J. D., Paquet, P. C. & Darimont, C. T. Science 343, 1311 (2014). Show context
  2. Artelle, K. A. et al. PLoS ONE 8, e78041 (2013). Show context
  3. Mowat, G., Heard, D. C. & Schwarz, C. J. PLoS ONE 8, e82757 (2013). Show context


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.


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

How do polar bears stay warm? Research finds an answer in their genes

polar bear looking straight at camera

New study is part of a broader genomic research program aimed at understanding what makes a polar bear a polar bear

A polar bear looking straight at the camera
A male polar bear. Credit: U.S. Geological Survey, Steven C. Amstrup
polar bear walking on an icy terrain
A male polar bear walks on pack ice. Credit: U.S. Fish and Wildlife Service, Eric Regehr
polar bear walking by water
A polar bear in Alaska. Credit: U.S. Fish and Wildlife Service, Steve Hillebrand
a polar bear lying down and facing camera
A polar bear at rest. Credit: U.S. Fish and Wildlife Service, Susanne Miller
Charlotte Lindqvist in front of a background showing a polar bear walking in a cold climate
Charlotte Lindqvist, assistant professor of biological sciences University at Buffalo led the study, which is part of a larger research program devoted to understanding how the polar bear has adapted to the harsh Arctic environment.
 In the winter, brown and black bears go into hibernation to conserve energy and keep warm.

But things are different for their Arctic relative, the polar bear. Within this high-latitude species, only pregnant females den up for the colder months.

So how do the rest survive the extreme Arctic winters?

New research points to one potential answer: genetic adaptations related to the production of nitric oxide, a compound that cells use to help convert nutrients from food into energy or heat.

In a new study, a team led by the University at Buffalo reports that genes controlling nitric oxide production in the polar bear genome contain genetic differences from comparable genes in brown and black bears.

“With all the changes in the global climate, it becomes more relevant to look into what sorts of adaptations exist in organisms that live in these high-latitude environments,” said lead researcher Charlotte Lindqvist, PhD, UB assistant professor of biological sciences.

“This study provides one little window into some of these adaptations,” she said. “Gene functions that had to do with nitric oxide production seemed to be more enriched in the polar bear than in the brown bears and black bears. There were more unique variants in polar bear genes than in those of the other species.”

The paper, titled “Polar Bears Exhibit Genome-Wide Signatures of Bioenergetic Adaptation to Life in the Arctic Environment,” appeared Feb. 6 in the journal Genome Biology and Evolution.

Co-authors include scientists from UB, Penn State University, the U.S. Geological Survey Alaska Science Center, Durham University and the University of California, Santa Cruz.

The genetic adaptations the research team saw are important because of the crucial role that nitric oxide plays in energy metabolism.

Typically, cells transform nutrients into energy. However, there is a phenomenon called adaptive or non-shivering thermogenesis, where the cells will produce heat instead of energy in response to a particular diet or environmental conditions.

Levels of nitric oxide production may be a key switch triggering how much heat or energy is produced as cells metabolize nutrients, or how much of the nutrients is stored as fat, Lindqvist said.

“At high levels, nitric oxide may inhibit energy production,” said Durham University’s Andreanna Welch, PhD, first author and a former postdoctoral researcher at UB with Lindqvist. “At more moderate levels, however, it may be more of a tinkering, where nitric oxide is involved in determining whether — and when — energy or heat is produced.”

The research is part of a larger research program devoted to understanding how the polar bear has adapted to the harsh Arctic environment, Lindqvist said.

In 2012, she and colleagues reported sequencing the genomes of multiple brown bears, black bears and polar bears.

In a paper in the Proceedings of the National Academy of Sciences, the team said comparative studies between the DNA of the three species uncovered some distinctive polar bear traits, such as genetic differences that may affect the function of proteins involved in the metabolism of fat — a process that’s very important for insulation.

In the new study, the scientists looked at the mitochondrial and nuclear genomes of 23 polar bears, three brown bears and a black bear.

The research was funded by the University at Buffalo and the National Fish and Wildlife Foundation.

Media Relations Manager, Architecture, Economic Development, Sciences, Urban and Regional Planning
Tel: 716-645-4655
Twitter: @UBScience
Pinterest: UB Science

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


Predators and their prey – why we need them both

by Joe Scott, international conservation director

Originally published in the spring/summer 2011 edition of Conservation Northwest Quarterly

Like CSI detectives investigating a crime scene, lynx and hare researchers in north central Washington recently responded to a “mortality” signal from a snowshoe hare that they had fitted with a satellite tracking collar to monitor hare movements. When they arrived at the scene the biologists were able to reconstruct the events around the hare’s demise.

Predators & prey: Why don’t predators eat all their prey?

A great horned owl had killed the hare, but predator became prey as a lynx killed the owl and pirated the hare for itself.

Everything eats snowshoe hares. In boreal forests, hares are the cheeseburgers for the fries, the fish for the chips, the meatballs for the spaghetti, and the corned beef for the cabbage.

Lynx are the most famous hare junkies, but the fleet-footed rabbits are also favored by wolves, coyotes, foxes, martens, eagles, goshawks, owls, and other raptors. In the ultimate insult, even red and ground squirrels eat them. People eat them.

Speed, stealth, aerial ambush and traps are all used on hares. Cute has no currency in the wilds, except as lunch. Scott Fisher, biologist with the Washington Department of Natural Resources, describes it this way: “When you’re a hare, everybody else on the block is a bully.”

But despite being every animal’s comfort food, snowshoe hares not only persist but do so in often ridiculous numbers.  How does an animal in such demand avoid being eaten out of existence?

It’s tempting to think that hares’ prodigious breeding ability is the evolutionary response to hyper predation.

But we have to dig a little deeper. All animals will have as many babies as they can successfully rear, whether their eggs are small and many or large and few, because that’s the best way of ensuring your genes survive in competition with those of your neighbors. And whether a species has many, many small eggs like a salmon, or a couple large eggs like a grizzly bear, it’s all about getting more of your genes out there, which is in turn rooted in the concept of ecological niches.

Predators & prey: What is a niche? Jobs in the woods


Paul Colinvaux describes a species’ niche as its place in the “grand scheme of things,” its “profession,” that is, “everything it does to get its food and raise its babies.” A plant or animal’s habitat is its address.

Spaces in each ecological niche, like welding jobs in a shipyard, are limited. Consequently the number of species that can fill a particular niche is more or less set by limitations on habitat imposed by climate, food, den sites, cover, etc—all the things that a species needs to survive and reproduce.

The niches, or jobs, of each species are crafted over millennia by natural selection. In other words, as Colinvaux concludes, “the common stay common and the rare stay rare,” unless something drastic happens to change the environment, like, for instance, clear cutting an old-growth forest or deregulating the financial industry. In each case you have a proliferation of weedy species, a reduction in diversity, and fewer real jobs.

Snowshoe hares have evolved to exploit a niche that has few competitors, since the boreal forests home to hares and lynx are very tough neighborhoods, especially in winter. In other words there are lots of hare “jobs” out there as long as the boreal remains the boreal and something doesn’t happen to radically alter it—like climate change.

So hares have lots of babies, very often, to supply the demand for hare jobs, not because so many animals like to eat them. High hare predation rates are a consequence of hare fecundity not a cause. Hare deaths are the grim cost of a reproductive strategy that floods the market with baby rabbits. And, lots of hares provide hare eating niches, or jobs, for many different predators.

So ultimately the numbers of any wildlife species are not determined by breeding strategies. They are set by opportunities for a particular plant or animal to live according to its needs. The number of welding jobs in the shipyard, not graduates of welding schools, determines the jobs for welders.

Predators & prey: Natural selection: Nature’s golden rule

Cooperation and conflict drive plant and animal adaptation. Species and their habitats thrive as interactive, dynamic systems that are constantly reshaping each other.

Natural selection is the ultimate arbiter—the universal law by which Mother Nature governs the biosphere. Quite simply, organisms are driven to survive, so prey animals respond over time with physical and behavioral adaptations to all the natural forces and conditions that conspire to kill them. Predators respond in kind with adaptations that allow them to exploit particular prey species. Otherwise neither would survive.

Predators have helped make snowshoe hares, well, snowshoe hares. Natural selection has equipped them with outsized hind legs and feet to run at lightening speed over snow. Their huge ears magnify the slightest sounds. Most ingeniously from a genetic standpoint, hares have developed a natural camouflage and change color with the seasons—white for winter, brown for summer. With so many things trying to eat them, they need lots of defensive weapons.

The hares that live longest and have the most babies pass more of those successful genes to the next generation, refining the traits over time, like camouflaged fur, that allow hares to escape lynx and owls long enough to reproduce, thus ensuring the survival of the species and its competitive “fitness” to adapt to dynamic landscapes and dozens of hungry predators.

Lynx are the ultimate hare specialists and as such their fortunes rise and fall with those of their big-footed prey. And they’ve kept pace in the evolutionary race for survival: their huge furry feet and long hind legs allow them to run and cut on top of snow like an NFL running back on juice. Many animals hunt hares but none with the efficiency of lynx. Yet they still can’t kill all the hares.

Predators & prey: Wild fluctuations

bighorn-does-david-moskowitz.jpgIn the north of their range, hare numbers have historically “crashed” spectacularly before rising again dramatically. In Alaska and western Canada, hare numbers rise and crash in roughly 10-year cycles, sometimes going from 10,000 to fewer than three animals per square mile in a single year. Female hares can produce two to five litters per year with three to four young per litter.

The phenomenon has been a source of scientific scrutiny for decades and was first described by fur trappers in the mid-nineteenth century. On large scales, scientists think that cyclical sun spot activity affects weather patterns and fire frequency in boreal forests, which in turn affect hare survival and food availability.

On smaller scales, over-browsing by the hyper-reproductive hares at their population zenith leads to food shortages that cause starvation and reduced reproduction, which in turn start the population declines. Just as the health of individual hares diminishes and they become more vulnerable to disease, predation from a larger number of hungry hare eaters kicks in and bingo, hares are scarcer than hens’ teeth—for a little while.

In essence, such wild fluctuations “reset” complex multiple predator prey systems until the next crash, rather like the way our economic and regulatory systems work—or not. Since they’re so tightly linked to snowshoe hares for food, lynx populations in the north rise and fall with them.

Northern lemmings undergo similar population booms and busts. Snowy owls are so tuned in to lemmings that they actually lay fewer eggs when lemming populations are down.

But such boom and bust predator prey economies are the exceptions, not the norms.

Predators & prey: From Arctic to Africa

Bees swarm, birds flock, fish school, and ungulates such as elk form herds because they’re less likely to become a predator’s next lunch special if they do so. Why some predators form groups, on the other hand, like lions in prides or wolves in packs, could have less to do with food sharing and more with defense of territories and rearing of young.

Research on the most well-known predator/prey dance partners on earth has shown that Africa’s Serengeti lions and wildebeest coexist in relative stability without the dramatic fluctuations in numbers that typify some arctic predators and prey like lynx and hares and lemmings and snowy owls.

A research team lead by John Fryxell of University of Guelph in Canada and Craig Packer from the University of Minnesota wanted to know why. Their modeling of four decades of data showed that wildebeest drastically reduced lion predation when they kept to groups and large herds.

Interestingly, the greater the tendency to form groups, the higher the stability of numbers of both species over time. According to Fryxell and colleagues: “When both the lions and wildebeest formed groups, predation was reduced even more. Compared with no-group ecosystems (all animals strewn across the Serengeti), grouping caused a 90-percent reduction in kill rates for lions.”

The complex social “cliques” seemed to work as ecosystem stabilizers, not dissimilar to human communities, with “both lion and wildebeest populations remaining relatively level over time.”

Social cliques among wild animals in the Serengeti are actually the glue that holds the ecosystem together and keeps population numbers stable. Wildebeest thrive in great numbers alongside zebra, Thompson’s gazelles, and several other ungulate species, all prey for lions, leopards, hyenas, crocodiles, hunting dogs, and cheetahs.

Predators & prey: Wolves and white-tails

There are 3,000 wolves in Minnesota. They eat on average about 50,000 of the estimated 450,000 white-tailed deer a year. This represents about 11.5 % of the deer population, with minimal supplements of snowshoe hares, beavers, and moose.

In a recent comprehensive 15-year study of white-tailed deer and wolves, the Minnesota Department of Natural Resources (MDNR) monitored the movements, survival, and mortality causes of 450 radio-collared does in four study areas. Simultaneously, department biologists monitored 55 radio-collared wolves from eight packs whose territories overlapped the deer study areas.

The research showed that doe mortality from wolves ranged from 4% to 22% per year but most typically was between 5% to 10% per year with the highest rate observed in the very severe winter of 1995-96.

Despite the fact that deer outnumber wolves in Minnesota by 150 to 1, wolves are not particularly effective hunters of white-tails.

According to the MDNR, “Wolves end up surviving primarily on the most vulnerable individuals in the deer population, such as very young, old, sick, injured, or nutritionally compromised deer, because those are the ones they can catch. The result being, that under certain conditions…many of the deer that wolves kill likely would have died from other causes, such as starvation or disease.”

Biologists refer to such predation impacts as “compensatory” as opposed to the “additive” effects of human hunters, who kill most prey in the prime of their reproductive lives.

Predators & prey: Where have all the mule deer gone?

doe-mule-deer-looking-out-david-moskowitz.jpgResearchers from Washington State University wanted to understand the reasons for long-term mule deer declines in the intermountain West. Hunters had long been blaming cougars. They were right…sort of. Cougars do kill mule deer. So do wolves, coyotes, bobcats, black bear, and grizzly bears.

But as with all natural systems, nothing’s that simple.

It turns out that the open, mixed forest habitat preferred by mule deer has been so dramatically altered in the West through irrigated agriculture that it’s provided wonderful white-tailed deer habitat. White-tails, historically rare in Washington, now outnumber mule deer in eastern Washington.

And as white-tailed deer numbers grow, mule deer decline. It appears as though landscape level habitat changes have created the white-tailed equivalent of tenements for cockroaches. It also appears that cougars have responded in kind.

But while there may be a slight uptick in cougar numbers as a result of increased ungulate numbers, cougar numbers have not exploded as some people seem to think.

“It’s particularly striking how little difference there is in resident cougar densities across cougar range in western North America,” says Gary Koehler, carnivore biologist, Washington Department of Fish and Wildlife. According to Dr. Koehler and his colleagues, “North American cougars exist in densities of about 1 to 2 adult animals per 100 sq. km everywhere they live—almost without fail. Female cougars are limited by prey availability, but males are limited by the availability of females in their territories, which they defend vigorously.”

However, the WSU researchers have found that cougar predation is having a greater impact on mule deer than on white-tails and occurs in the summer when white-tails move into higher elevation mule deer habitat. Mule deer are the “secondary” prey, but as they’re already in decline, predation is having a greater effect on them.

A similar dynamic has happened with mountain caribou in British Columbia’s inland rainforest. As the caribou’s historically extensive old-growth forest habitat has been increasingly fragmented, it’s opened more niches for deer, elk, and moose. Cougars and wolves follow and opportunistically prey on caribou which cannot withstand the “new normal.” For centuries the mountain caribou old forest and high elevation niche was at the heart of their predator avoidance strategy. Predators simply weren’t able to get to them enough to make a difference in caribou numbers.

Like steelworker jobs in Pittsburgh, jobs for mountain caribou have diminished. Now the wolves are literally at the door and it’s forced some tough choices for managers and conservationists alike until the habitat and historic prey species numbers are restored.

The Mule Deer Working Group of the Western Association of Fish and Wildlife Agencies has been studying mule deer dynamics, particularly mortalities and predation.

According to their findings, many factors confound the question about mule deer declines. Most deer mortality occurs in young animals soon after birth or in winter of their first year. Some biologists believe that the question of whether mortality is compensatory or additive is density dependent—it has to do with how many of the mule deer jobs are filled—also referred to as “carrying capacity” or the ability of the habitat to support the herd.

Carrying capacity can be measured by the overall condition of the animals and their range. When the herd numbers are consistent with what the habitat can support—at carrying capacity—deaths that happen are compensatory. They will occur one way or another naturally keeping animals at levels where the land to support them. As numbers of deer fall below range capacity, additional deer deaths become additive—and unsustainable, contributing to herd declines.

Climatic conditions such as long-term drought or severe winters can reduce the quality of the range and thus the overall physical condition of mule deer making them more vulnerable to predation. Significant habitat changes that result in different movement patterns could make deer even more susceptible to predation.

According to the Working Group, “…most of the environments where mule deer exist today have been altered by fire suppression, development, habitat fragmentation” etc. In these habitats (most of the West), biologists believe predation does not cause declines in deer populations. The effect predators have on prey populations in these environments is more complex and related to how humans affect predators, prey and habitat, and the types and densities of predators that exist.

“In years when mule deer populations are lean, some predators such as mountain lions and wolves may consume several wildlife species including elk and small mammals, causing the predators to maintain artificially high numbers. While this has the potential to slow the growth of mule deer populations, scientific studies show that reducing predators does not increase the number of fawns that survive to adulthood. And it’s the number of fawns that survive to adulthood that determines the growth rate of a mule deer population.”

Predators & prey: Why big fierce animals are rare

lynx-hunting-photo-c-patrick-reeves.jpgEverybody knows that, in nature, small things are common and large things are rare. To understand why, we need to dust off our high school physics textbooks and reacquaint ourselves with the second Law of Thermodynamics, which dictates that the harvesting of solar energy cannot be 100% efficient. This is the real reason that big fierce animals are rare. And rarity is one reason that predators can’t eat all their prey or compromise their numbers to the point that those prey animals are themselves threatened as species.

Ecosystems have structure, like the rows of stone in a pyramid. This structure is organized into what ecologists call “trophic levels,” which are quite simply the different plant and animal communities that inhabit a given area. In a typical simple system there are three trophic levels: plant communities, herbivores, and carnivores. Plants form the large pyramid base, herbivores in the middle level, carnivores at the small, pointy top.

Plants are less than 10% efficient converting light energy to produce plant tissue. Ninety percent is lost as heat to the atmosphere. In the transfer of energy to the second trophic level, the herbivores follows suit, so essentially energy is degraded by 90% at each level from plants through herbivores to carnivores. Of the 1000 calories of solar energy captured by a plant, 100 calories are available to a deer, and 1 calorie is available to a wolf, to grow, reproduce, and have enough strength and energy to hunt again. For this simple reason alone, predators generally can never number more than 10% of their prey.

The upshot is that predators have to work really hard to make a living. It’s definitely blue collar: complete with long hours, physical exertion, shorter life span, high risk of injury or death, and being frequently ostracized by neighbors. For example, wolves are considered efficient hunters for only about two years of their lives and rarely live beyond seven years in the wild.

Predators are limited by available calories, particularly in winter, territorial behavior, the rigors and risks of hunting, rapid decline in their athletic abilities. It’s no life of Reilly. The Second Law of Thermodynamics and natural selection have seen to it.

Predators & prey: Balance in all things

The bottom line is that ecosystems are complex. And, like it or not, predators are a necessary and beneficial part of natural systems. If we remove them from the picture, there are consequences.

Predators provide ecological stability by regulating the impacts of grazing and browsing animals, thus ensuring the overall productivity of the habitat. They cull weak, sick, and old prey, thus ensuring the maximum fitness of elk, deer, antelope, and hares. They foster biological diversity by “enforcing” ecological boundaries or preventing what ecologists refer to as “competitive exclusion,” the tendency of one prey animal to outcompete another. So-called “apex predators,” the wolves, lions, and tigers are the Godfathers, as they also control the numbers of “meso predators,” the coyotes, raccoons, possums, foxes—even domestic cats—which when left unchecked can do enormous damage to birds and native rodents.


Study shows overkilling of grizzly bear population

Six biologists, including four from Simon Fraser University, cast doubt on the scientific soundness of management of British Columbia, Canada’s grizzly bear population in a new paper published online in the scientific journal PLOS ONE.

The SFU co-authors are: Kyle Artelle, the study’s lead author, Raincoast biologist, and doctoral student; John Reynolds, a professor and Artelle’s co-supervisor; Andrew Cooper, a School of Resource and Environmental Management associate professor; and Sean Anderson, a doctoral student co-supervised by Cooper and Nick Dulvy, an SFU biologist.

The manuscript, Confronting uncertainty in wildlife management: performance of grizzly bear management, was a collaboration between biologists from SFU, the University of Victoria, and the Raincoast Conservation Foundation.  It is the first independent, peer-reviewed study of the Ministry of Environment’s grizzly bear hunt management program.

The authors tested whether government policy assured the sustainability of its trophy hunt for grizzlies from 2001 to 2011. In this period, out of an estimated population of 15,000 bears, more than 3,500 bears (including more than 1,200 females) were killed. Legally sanctioned trophy hunting took more than 2,800 bears (including more than 900 females) in the kill.

In reviewing the government’s 2001-2011 record of all human-caused mortality, the researchers discovered that the number of kills exceeded government sanctioned limits in half of the populations open to hunting.

In addition to a high number of overkills, the researchers discovered that the government might have underestimated the risk of overkills in up to 70 per cent of its records.  This was based on computer simulations that considered uncertainty in the true sizes of populations currently estimated, sustainable mortality rates, and poaching.

“Fortunately, through hunting permit allocations the government has an easy tool at its disposal to help safeguard these populations. Even considering non-hunting kills and management uncertainty, most overkills could have been prevented by reducing or eliminating hunting pressures,” says Artelle.

Cooper and Reynolds note that the lessons learned about the need to err on the side of caution in setting mortality limits in grizzly bear management are universally applicable to any species’ management.

“The concepts that underpin this study have been common currency in the fisheries realm for decades,” says Reynolds. “Unfortunately, we have yet to see them broadly adopted by terrestrial managers.”

“There will always be uncertainty in management,” adds Cooper. “This paper shows how important it is for wildlife managers to address it, and provides first steps for doing so.”