Rapid declines of large mammal populations after the collapse of the Soviet Union

Poster Bragina by Roberta Kwok

When a country goes into economic freefall, the resulting chaos can trigger a host of environmental changes. Wildlife regulation often falls by the wayside, and poaching rises — but activities such as logging may drop. “Thus, socioeconomic shocks may hinder or help conservation,” researchers write in Conservation Biology. In the case of the 1991 Soviet Union collapse, which was it? The team studied population trends for 8 mammal species in Russia, including deer, bears, lynxes, and grey wolves. For data, they turned to the Russian Federal Agency of Game Mammal Monitoring’s records. That database contains annual tallies for mammal species, obtained by methods such as counting tracks in the winter and surveying hunters. The researchers studied data from 1981 to 2010, covering the decade before the collapse and the two following decades. Continue reading

Advertisements

Drastic population fluctuations explain the rapid extinction of the passenger pigeon

The number of passenger pigeons went from billions to zero in mere decades, in contrast to conventional wisdom that enormous population size provides a buffer against extinction. Our understanding of the passenger pigeon’s extinction, however, has been limited by a lack of knowledge of its long-term population history. Here we use both genomic and ecological analyses to show that the passenger pigeon was not always super abundant, but experienced dramatic population fluctuations, which could increase its vulnerability to human exploitation. Our study demonstrates that high-throughput–based ancient DNA analyses combined with ecological niche modeling can provide evidence allowing us to assess factors that led to the surprisingly rapid demise of the passenger pigeon.

To assess the role of human disturbances in species’ extinction requires an understanding of the species population history before human impact. The passenger pigeon was once the most abundant bird in the world, with a population size estimated at 3–5 billion in the 1800s; its abrupt extinction in 1914 raises the question of how such an abundant bird could have been driven to extinction in mere decades. Although human exploitation is often blamed, the role of natural population dynamics in the passenger pigeon’s extinction remains unexplored. Applying high-throughput sequencing technologies to obtain sequences from most of the genome, we calculated that the passenger pigeon’s effective population size throughout the last million years was persistently about 1/10,000 of the 1800’s estimated number of individuals, a ratio 1,000-times lower than typically found. This result suggests that the passenger pigeon was not always super abundant but experienced dramatic population fluctuations, resembling those of an “outbreak” species. Ecological niche models supported inference of drastic changes in the extent of its breeding range over the last glacial–interglacial cycle. An estimate of acorn-based carrying capacity during the past 21,000 y showed great year-to-year variations. Based on our results, we hypothesize that ecological conditions that dramatically reduced population size under natural conditions could have interacted with human exploitation in causing the passenger pigeon’s rapid demise. Our study illustrates that even species as abundant as the passenger pigeon can be vulnerable to human threats if they are subject to dramatic population fluctuations, and provides a new perspective on the greatest human-caused extinction in recorded history.

This article contains supporting information online at http://www.pnas.org/content/suppl/2014/06/13/1401526111.DCSupplemental/pnas.1401526111.sapp.pdf

Reference:

Chih-Ming HungPei-Jen L. Shaner,Robert M. ZinkWei-Chung Liu,Te-Chin ChuWen-San Huang, Shou-Hsien Li

Drastic population fluctuations explain the rapid extinction of the passenger pigeon PNAS 2014 published ahead of printJune 16, 2014,

http://www.pnas.org/content/early/2014/06/11/1401526111?

Montana’s Glaciated Plains: Thinking Big Across Time and Space

Posted by Sean Gerrity of American Prairie Reserve, National Geographic Fellow on November 2, 2012 

American Prairie Reserve’s mission to create a reserve of more than three million acres represents one of the largest conservation projects in the United States today. The size of the project is hard to grasp – even a small piece of the 274,000 acres that currently comprise the Reserve seems like an endless “sea of grass” to both first-time and seasoned visitors. However, after ten weeks of research on historical wildlife populations of Montana’s glaciated plains, I have become increasingly convinced that APR’s vision is necessary. If we want to understand the behavior and ecology of grassland species, we need to think big.

America’s iconic species – bison, pronghorn, elk, wolves, grizzly bears – evolved over tens of thousands of years on a wide-open continent. Over this long period of time, these species became well adapted to environmental “stochasticity,” the highly dynamic and unpredictable nature of their habitat. In fact, the prairie is one of the most dynamic ecosystems in the world.

Pronghorn race across the plains. Photo courtesy of Diane Hargreaves.

Settlers came to Montana in the early 20th century after being told that if they turned the soil they could transform the rugged landscape and cultivate a fertile Eden. A few years of unusually (and well-timed) wet conditions in the 1910′s bolstered this belief, but a severe drought in the 1920′s caused devastation for most agricultural producers. Unlike its settlers, though, the region’s wildlife had evolved several adaptations to deal with these rapid and extreme fluctuations. It turns out that the key to persistence in a highly stochastic environment is to employ a range of survival techniques.

On a wide-open continent, ungulates like elk, deer and pronghorn thrived in many different habitats and were able to chose from a toolkit of survival strategies grounded in their history and experience on the land. If conditions were optimal, herds would be inclined to stay put, but in periods of high environmental variance, they would have had to choose a new strategy. For instance, when temperatures dropped abnormally low, ungulates fled the prairie and sought thermal refuge in the Missouri River Breaks or the Rocky Mountains.

Elk in Autumn. Photo courtesy of Gib Myers/APR.

Through my research, I also discovered the debate over whether bison were historically a migratory or a nomadic species. Did they follow specific migratory patterns, or did they move in a sporadic, localized manner related to the availability of food? We’re not sure, but the truth is probably somewhere in the middle. Regardless, much of the migratory behavior that we observe in terrestrial species today is shaped by human intervention. We have severely restricted the habitats of most wildlife species, and climate change threatens what marginal areas remain.

Recent studies predict that changes in climate, such as increases in severe weather events and changes in precipitation levels, will affect grassland ecosystems, from native plant and weed distribution to altered fire regimes. Conservation planners will have to react to these to the best of their ability within the limits of science, funds, and space.

For the ungulate species that American Prairie Reserve (APR) is trying to recover, bigger is better. A large reserve would allow wildlife to utilize more of the strategies in their survival toolbox. It may also be able to buffer the adverse effects of climate change by encompassing more habitat niches and providing more space for wildlife to disperse while still remaining within reserve boundaries. Furthermore, a large area has the capacity to support higher numbers of wildlife, which greatly reduces the risk of a population extinction event.

Late afternoon light on the Reserve. Photo courtesy of Michelle Berry.

American Prairie Reserve recently celebrated the acquisition of a 150,000-acre property that more than doubled the size of previous habitat and added 16 miles of shared border with the 1.1 million-acre Charles M. Russell National Wildlife Refuge. Even though the goal of APR seems very ambitious at times, we must remember that wildlife persisted on a much larger landscape for thousands of years before Lewis and Clark ever walked on this land.

Thus, it is a mistake to conceptually box these species into a specific habitat-type or set of behaviors. As Lewis put it, the historical American West contained “immence herds of Buffaloe, Elk, deer and antelopes feeding in one common and boundless pasture.” While we will never be able to recapture the full picture of historical wildlife on the frontier, American Prairie Reserve can reestablish a pretty big chunk of that natural legacy.

American Prairie Reserve intern Michelle Berry is a Master’s student in environmental studies at Stanford. She has been tasked with examining historical works of literature and other primary sources to establish wildlife population estimates in the Reserve region of northeastern Montana.Her 10-week internship was made possible by the Bill Lane Center for the American West.

Source: http://newswatch.nationalgeographic.com/2012/11/02/montanas-glaciated-plains-thinking-big-across-time-and-space/

The origin of recently established red fox populations in the contiguous United States: translocations or natural range expansions?

The origin of recently established red fox populations in the contiguous United States: translocations or natural range expansions?

European Red Fox (Slovenia)

STATHAM, M. J., B. N. SACKS, K. B. AUBRY, J. D. PERRINE, AND S. M. WISELY

Red foxes (Vulpes vulpes) are native to boreal and western montane portions of North America but their origins are unknown in many lowland areas of the United States. Red foxes were historically absent from much of the East Coast at the time of European settlement and did not become common until the mid-1800s. Some early naturalists described an apparent southward expansion of native foxes that coincided with anthropogenic habitat changes in the region.

Alternatively, red foxes introduced from Europe during Colonial times may have become established in the east and subsequently expanded their range westward. The red fox also was absent historically from most lowland areas of the western United States. Extant populations of red foxes in those areas are considered to have arisen from intentional introductions from the east (and by extension are putatively European), escapes or releases from fur farms, or range expansions by native populations.

To test these hypotheses we compared mitochondrial DNA sequences (cytochrome band D-loop) from 110 individuals from 6 recently established populations to 327 native (primarily historical) individuals from Eurasia, Alaska, Canada, the northeastern United States, and montane areas in the western contiguous United States, and to 38 individuals from fur farms
red fox.

We found no Eurasian haplotypes in North America, but found native haplotypes in recently established populations in the southeastern United States and in parts of the western United States. Red foxes from the southeastern United States were closely related to native populations in eastern Canada and the northeastern United States, suggesting that they originated from natural range expansions, not from translocation of European lineages, as was widely believed prior to this study.

Similarly, recently established populations in the Great Basin and in western Oregon originated primarily from native populations in western montane regions, but also contained a few nonnative North American haplotypes. In contrast, populations in western Washington and southern California contained nonnative, highly admixed stock that clearly resulted from intracontinental translocations. Several common haplotypes in these populations originated in regions where fur-farm stocks originated.

Although European red foxes translocated to the eastern United States during Colonial times may have contributed genetically to extant populations in that region, our findings suggest that most of the matrilineal ancestry of eastern red foxes originated in North America.

Statham, M. J., B. N. Sacks, K. B. Aubry, J. D. Perrine, and S. M. Wisely. 2012. The origin of recently established red fox populations in the United States: translocations or natural range expansions?. Journal of Mammalogy 93(1):52-65.
Access to the original paper in pdf: http://www.fs.fed.us/pnw/pubs/journals/pnw_2012_statham001.pdf

Gordon Haber said “It’s not how many wolves you kill, it’s which wolves you kill”

The U.S. Fish and Wildlife Service’s decision to delist gray wolves nationwide is flawed because it’s based on the total number of wolves, a statistical approach that, according to wolf biologist Gordon Haber, is “ecological nonsense.”

Haber spent over 43 years observing Alaska’s wild wolves, mostly in Denali National Park, before dying in a plane crash while tracking the animals. To locate wolves, he snowshoed, skied and flew in winter; he backpacked and hiked in summer. He endured minus-50-degree Fahrenheit temperatures, blizzards, thunderstorms, mosquitoes and the risk of grizzly and moose attacks. Few modern biologists have such unassailable experiential authority.

Haber’s take-home message was this: You can’t manage wolves by the numbers. You can’t count the number of wolves in an area and decide whether it’s a “healthy” population, because what really counts is the family group, or pack, as some still call it.

“Wolves are perhaps the most social of all nonhuman vertebrates,” wrote Haber. “A ‘pack’ of wolves is not a snarling aggregation of fighting beasts, each bent on fending only for itself, but a highly organized, well-disciplined group of related individuals or family units, all working together in a remarkably amiable, efficient manner.”

Haber devoted his career to studying intact family groups, especially the Toklat wolves of Alaska. First made famous by Adolph Murie’s 1944 book “The Wolves of Mount McKinley,” the Toklats rank with Jane Goodall’s chimpanzees as the two longest-studied mammal social groups in the wild.

Wolves go to great lengths to stay with family; when important members are lost, families can disintegrate and remaining individuals often die. Haber knew this firsthand owing to an alpha female wolf, who, after her mate was killed in a botched government darting study, died of starvation, alone. Relocated wolves travel hundreds of miles to return home. And the first wolf seen in California in 90 years, OR7, has never stopped moving: He’s searching for a mate, for family.

Left unexploited (that is, not killed) by humans, wolves develop societies that are astonishingly complex and beautifully tuned to their precise environment. Once, Haber observed the Toklat wolves moving their den because heavy winter snow had decimated the moose population; a week before pupping, the wolves shifted to another den closer to caribou. He also recorded unique hunting methods, among them moose hunting by the Savage River family that he called “storm-and-circle.”

Family groups develop unique and highly cooperative pup-rearing and hunting techniques that amount to cultural traditions, though these take generations to mature and can be lost forever if the family disintegrates. After the entire Savage River family was shot illegally in the winter of 1982-’83, Haber never saw the storm-and-circle technique again.

A healthy wolf population is more than x number of wolves inhabiting y square miles of territory. The notion that we can “harvest” a fixed percentage of a wolf population corresponding to natural mortality rates and still maintain a viable population misses the point. According to Haber, it’s not how many wolves you kill, it’s which wolves you kill.

Natural losses typically take younger wolves, whereas hunting and trapping take the older and more experienced wolves. These older wolves are essential because they know the territory, prey movements, hunting techniques, denning sites, pup rearing — and because they are the breeders. Haber observed this many times: Whenever an alpha wolf was shot or trapped, it set off a cascade of events that left most of the family dead and the rest scattered, rag-tag orphans.

It happened again in April 2012. A trapper dumped his horse’s carcass along the Denali National Park boundary, surrounded it with snares, and killed the pregnant alpha female of the most-viewed wolf group in Denali. With her death, the family group had no pups, and it disintegrated, shrinking from 15 to three wolves. That summer, for hundreds of thousands of park visitors, wolf-viewing success dropped by 70 percent.

This is not unique to Alaska. In 2009, Yellowstone National Park’s Cottonwood group disappeared after losing four wolves to hunting, including both alphas. In 2013, the park’s Lamar Canyon family group splintered when the alpha female — nicknamed “rock star” — was shot.

So it’s never about numbers. It’s about family. A wolf is a wolf when it’s part of an intact, unexploited family group. Wolves are no longer endangered when these groups have permanent protection, and when we manage according to this essential functional unit. If we leave wolves alone, we’ll be the ones to benefit.

The government has extended the comment period for delisting gray wolves from Endangered Species Act protection to Dec. 17, 2013. Go to http://www.regulations.gov and click on Gray wolf: Docket N. (FWS-HQ-ES-2013-0073).

Marybeth Holleman is a contributor to Writers on the Range a service of High Country News (hcn.org). With Gordon Haber, she is the author of Among Wolves: Gordon Haber’s Insights into Alaska’s Most Misunderstood Animal. She also runs the blog Art and Nature and lives in Anchorage, Alaska.

Source: http://www.summitdaily.com/news/8780038-113/wolves-family-haber-wolf

A small drop in one species’ population can drive others to actually die out

by 

When we think of extinction, we often picture the last individual of its kind leading a solitary life until its death marks the species’ disappearance from the face of the Earth. Called “numerical extinction,” this is the traditional concept of extinction, and it forms the basis for many conservation decisions.

But there is another type, called “functional extinction,” which takes a more ecological approach. Some scientists argue that the threshold for extinction should not be the complete disappearance of a species, but instead the point at which there aren’t enough individuals left in that species to perform whatever roles it was playing in the ecosystem. A species can be considered functionally extinct when its dwindling numbers cause another species in the same food web to disappear from the natural community first. These extinctions are important to understand since a species can go functionally extinct well before the population is small enough to put it in danger of a numerical extinction.

A recent theoretical paper in Nature demonstrates that functional extinctions occur at a surprisingly high frequency. The paper suggests that they should be considered when making conservation decisions and setting environmental policy.

Using both natural and computer-generated food webs, the researchers ran analytical models to examine how often functional extinctions happen and to identify the circumstances in which they occur. The model food webs were generated based on roles that species tend to play in real food webs, and they followed general rules common to most ecosystems (such as large animals being less abundant than smaller animals). In each web, the relationships between each species—such as who eats what, how much they eat, and how often—was either known (in the case of the natural webs) or calculated (in the case of the model webs).

To investigate what happens in a food web when a particular population declines, the researchers focused on each species separately and increased its mortality rate until an extinction occurred. If the species they manipulated was the one that disappeared, the extinction could be considered a numerical extinction; if a different species in the ecosystem disappeared as a result of the manipulation, the extinction was functional. The researchers found that functional extinctions happened at a surprisingly high rate: the probability of a functional extinction, compared to a numerical one, was 0.49 in the natural food webs and 0.72 in the model webs. In the authors’ words, “a species’ ecological functionality is often lost long before its existence is threatened.”

Furthermore, a species doesn’t have to be down to its last few straggling survivors in order to lose its ecological effectiveness. More than a quarter of the species in the natural food webs and more than half of those in the computer-generated webs became functionally extinct after losing just thirty percent of their population. That’s a pretty frightening statistic: a die-off of less than a third of a species’ members can unbalance an ecosystem enough to trigger the complete extinction of another species in the community.

Food webs are incredibly complicated and nuanced, and the results demonstrate the delicate balance of ecological communities. In the study, many of the species that disappeared as a result of a functional extinction weren’t even directly linked to the dying species in the food web. In other words, they were driven to extinction by a small decline in a species they don’t eat (and which doesn’t eat them).

Of course, this study was a simplistic representation of what goes on in actual ecological communities. However, if anything, it’s probably a conservative estimate of the damage that increasing mortality rates and decreasing population sizes can cause. In all likelihood, the effects of a changing world—including climate change, decreasing forest cover, and human-wildlife conflict—can wreak even more havoc on ecosystems than this study suggests.

The bright side is that understanding functional extinctions can inform our decisions about managing and conserving species. For instance, the researchers found that there is an inverse relationship between a species’ body mass and its tendency to go numerically, rather than functionally, extinct; the bigger an animal is, the more likely it is that increasing its mortality rate will drive another species to extinction. This type of knowledge could help prioritize where conservation efforts and resources should go. However, to make this type of information useful, scientists must continue to investigate extinction in a more ecological sense, and policymakers must be willing to take the results into account.

Nature, 2013. DOI: 10.1038/nature12277  (About DOIs).

Source: http://arstechnica.com/science/2013/07/not-yet-gone-but-effectively-extinct/

Officials confirm that Finland’s wolf population has collapsed because of poaching

Wolf numbers have nearly halved since 2005

Finland’s wolf population in February 2007 and February 2011, and the development in 1978-2011. Helmikuu = February, lauma = pack, susipari = a pair of wolves, yksilöä vähintään = minimum number of individuals.
The map shows clearly that the number of packs has been thinned out dramatically south and east from Oulu and in the south-eastern corner of the country. Absolute numbers have fallen from around 250 in 2005 to barely half of that today.
By Heli Saavalainen

It has been an open secret for years, but now it is official: poaching has caused Finland’s wolf population to collapse in such a way that the species, which is already considered extremely threatened, is now indeed in dire straits.
The Ministry of Agriculture and Forestry, under whose jurisdiction beast of prey issues fall, plans to get out into the field in the Game Councils next winter in order to root out the deeply-rooted hatred towards wolves.
“The idea is to start unravelling the conflict systematically”, says negotiating official Sami Niemifrom the ministry.
The administration has been under a lot of pressure to keep the tightly-protected wolves alive, for Finland is already being monitored by the EU Commission because of the illegal killings of wolves.
The ministry, therefore, calls for extensive cooperation between various authorities in order to curb poaching.
“We will now begin – hopefully – together with several ministries to think of ways to tackle this situation. This cannot be just the Ministry of Agriculture and Forestry’s responsibility. The Ministry of the Interior and the Ministry of the Environment have to be included”, Niemi emphasises.

The number of wolves in the country has dropped by more than a hundred from the peak years.
When in 2005 there were 250 wolves in Finland, last spring’s corresponding figure was between 135 and 145.
The number of separate wolf packs is estimated by the the Finnish Game and Fisheries Research Institute at 13 or 14, when half of the packs on the Finnish-Russian border are included.
The packs are more or less in their former locations, but from some areas wolves have disappeared completely. For example several packs south and east of the city of Oulu have simply ceased to exist.

A more concerted investigation into the reasons behind the steadily diminishing number of wolves was commenced within the Ministry of Agriculture and Forestry last spring.
Now poaching has been ascertained as the main cause: on Tuesday, September 20th, the ministry confirmed in the Etelä-Saimaa daily that no other reasons lurk behind the collapse of the wolf population.
The wolves have not voted with their feet and migrated to Russia, and they have not died of illnesses either. Legally, with the requisite permits, only nine wolves were killed last year.
“Finland has such a strong and healthy elk population that the packs would have no reason suddenly to abandon their territories. It is also known that genetically Finland’s wolf population is strong and it does not carry illnesses. Licenced culling of wolves has been moderate with respect to the increase of the population”, Niemi lists.
“So, the only explanation left to us is illegal killings.”

More and more poaching incidents have come to the knowledge of the authorities and an increasing number of cases are being looked into.
In the spring, the Penal Code was changed in such a way that the law now includes enactments related to aggravated poaching and aggravated concealment of an illegal catch.
To investigate such deeds, the police was given the right to use coercive measures such as monitoring telephone traffic.
“But the issue cannot be solved simply by increasing supervision, for in the background there is a conflict problem”, Niemi emphasises.

To resolve the conflict, dialogue is needed between the authorities and the hunters. In Niemi’s view the Game Centre of Finland, which was launched in March through the amalgamation of the Hunters’ Central Organisation
and 15 Game Management Districts, is a good place for the planning of Finland’s beast of prey policies.
“For the first time, we have a structural chance to seize the beast of prey conflict and dismantle it, so to speak. The idea is to begin systematically to unravel the old notions and fears together with the Game Centre of Finland and its councils”, Niemi says.
“If we cannot find a solution to the poaching issue this way, hopefully we will at least be able to bring the conflict under control.”

Helsingin Sanomat / First published in print 21.9.2011