Tuesday, April 18, 2017

Only two Isle Royale wolves


For the second year in a row, the Isle Royale wolf population remains a mere two. Researchers from Michigan Tech say that as the wolf population stays stagnant, the moose population will continue to grow at a rapid pace. And this could have a significant impact on the island's famed forests.
According to Rolf Peterson, a research professor at Michigan Tech and co-author of the report, the Isle Royale wolves are no longer serving their ecological function as the island's apex predator--the creature at the top of the food chain. With only two wolves left on the island, the moose population has grown to an estimated 1,600. 
Without wolf predation, says John Vucetich, a professor of ecology at Michigan Tech and report co-author, the moose population could double over the next three to four years. And more moose means more vegetation is eaten. The observations were reported in this year's Winter Study, which marks the 59th year of monitoring wolves and moose on Isle Royale, the longest running predator-prey study in the world. 
Wolf Genetics
Where have all the island wolves gone? The answer lies in genetics. The population crash on Isle Royale is the result of inbreeding--the remaining wolves are not only father and daughter, they are also half siblings who share the same mother.
Researchers believe the two have probably mated at least once in the past: in 2015, an approximately nine-month-old pup was spotted with the two adults. That pup, however, did not appear healthy. Researchers noted a visibly deformed tail, small stature and possibly abnormal posture. Peterson and Vucetich were not surprised when the pup failed to appear with the adults in 2016.
The remaining wolves are not expected to successfully reproduce in the future, either. Both animals are approaching old age--the female is seven years old and the male is nine--and no one can predict how much longer either wolf will live. Further complicating matters, the female wolf has been observed aggressively rejecting the male as a mate.
But even if the pair were to produce a healthy pup, it would likely have little impact on the Isle Royale ecosystem. In the case of these wolves, extreme inbreeding makes the population's natural recovery unlikely. The wolves' numbers started plummeting in 2009, declining by 88 percent from 24 to 2 wolves. Vucetich and Peterson believe this is a result of inbreeding, and all geneticists who have studied the situation agree that recovery is unlikely without new genetic material.
At the end of 2016, the National Park Service published a Draft Environmental Impact Statement (DEIS) to determine how best to manage the wolves on Isle Royale. The DEIS discussed four potential courses of action. According to the document, NPS would prefer a time-limited introduction of new wolves--up to 20 to 30 wolves selected to maximize both genetic diversity and restore predation to the ecosystem. NPS estimates that the process to introduce the number of wolves identified in the plan would take between three to five years. Public review of the document concluded in mid-March, and the NPS is reviewing all comments. A final decision is expected in the fall.
More Moose 
The 2017 moose census puts the Isle Royale herd at approximately 1,600 members. According to the report, the multiyear trend shows the moose population has been growing at a six-year average rate of 21.6 percent. Peterson and Vucetich credit this rapid growth to several factors: high reproduction rates, low rates of mortality due to wolf predation, mild winters and an abundance of forage. 
But this abundance of forage may not last. According to recent findings, under the island's current conditions, the moose population could double over the next three to four years. If this happens, the number of Isle Royale moose would reach an unprecedented high for the project's six-decade history. And this could result in high levels of browsing on the island's vegetation.
"Everything we're seeing on Isle Royale is consistent with our past understanding of the ecosystem's dynamics," says Vucetich. "We have every reason to expect the moose population will continue to grow and increasingly impact the forest."
Moose aren't the only Isle Royale residents experiencing a population boom with a dwindling number of wolves. The report notes that the number of beaver colonies has increased dramatically over the past six years, from approximately 100 to nearly 300. 
"Wolves are the only significant predator of beaver on Isle Royale," says Peterson. "Beaver were nearly extinct across North America 200 years ago. At Isle Royale, they're now at unprecedented levels."
With wolves no longer serving their predatory function, Isle Royale's ecosystem could soon look dramatically different.

Thursday, April 6, 2017

Wolves often rely on human foods


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

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

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

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

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


Thursday, March 23, 2017

Coyotes can't match wolves' hunting prowess



Eastern wolves once roamed forests along the Atlantic coast, preying on moose, white-tailed deer and other hooved mammals collectively known as ungulates. As the wolf population plummeted via the rifle and the trap, however, the eastern coyote inherited the status of apex predator in those habitats.
But a study from John Benson and colleagues provides evidence that the eastern coyote hunts moose and other large prey far less frequently than does the eastern wolf -- instead preferring to attack smaller game or scavenge human leftovers.
The findings help resolve long-standing questions about whether eastern coyotes have filled the ecological niche left vacant when the eastern wolf became threatened, Benson said.
"Wolves rely on large prey to survive," said Benson, assistant professor of vertebrate ecology who conducted the research as a doctoral student at Trent University. "But the smaller size of coyotes appears to give them dietary flexibility to survive on a wider variety of food and prey sizes, making them less predictable predators of large prey.
"Having a top predator that preys consistently on large animals like deer and moose may be an important part of maintaining stable predator-prey dynamics and healthy, naturally functioning ecosystems."
After GPS-tracking 10 packs of eastern wolves and analyzing their kill sites in Ontario, the team estimated that the wolves consumed 54 percent of their ungulate meat from moose and 46 percent from white-tailed deer. By contrast, eight packs of eastern coyote ancestry that occupied separate but neighboring territories got just 11 percent of their ungulate meat from moose and 89 percent from deer.
The eastern wolf weighs between 50 and 65 pounds; the eastern coyote typically hits 40 to 50. Though the extra weight gives eastern wolves a greater chance of killing a moose - or at least surviving the encounter - it also demands the greater caloric intake that moose and other meaty prey can provide.
Because wolves need to feed on large prey, their populations tend to rise and fall together, Benson said. Wolves may kill many moose during a winter, for instance, depleting their numbers. With fewer moose available, the wolf population declines, boosting the moose population, which in turn boosts the wolf population, and so on.
Yet the buffet-style menu of the eastern coyote means that its numbers can remain steady or even rise without large prey if alternative food is abundant. This opportunistic diet, Benson said, might also be driving erratic population swings among those lower on the food chain.
"It's important to understand the role that wolves play in ecosystems and to not assume that smaller predators ... perform the same ecological functions," Benson said. "If coyotes start hammering white-tailed deer, and deer start to decline, then (coyotes) can just eat rabbits or squirrels or garbage but continue to prey on deer, too. So we think that could be a destabilizing element.
"There are some areas where you've got way too many white-tailed deer in the east, and then you've got other areas where hunters are concerned because the deer are declining. That speaks to the fact that coyotes are an unpredictable predator."
The study is timely: Canada recently designated the eastern wolf as threatened, with the vast majority of eastern wolves living protected in Ontario's Algonquin Provincial Park.
Human-caused mortality has limited efforts to expand the population beyond Algonquin Park, Benson said, which is made worse by the fact that wolves there are likely naïve to the dangers posed by humans. Another issue: Eastern wolves readily breed with eastern coyotes in the wild, making it difficult to maintain a pure lineage.
"Is there a way to get them to expand numerically and geographically outside of the park? We're not sure at this point," said Benson, who provides advice to a team now developing a recovery plan. "One thing that can be managed is human-caused mortality, so if we can provide additional protection, that should put them on equal demographic footing.
"It's an incredibly challenging situation that is complicated by the interactions of these wolves with coyotes and humans. If the park stays the same, there's no immediate reason that they would go extinct. However, we wouldn't want to go forward with that as our only plan because it offers little chance for expansion."
Though large-scale reintroduction across eastern North America will probably not occur soon, Benson said the study emphasizes the value of preserving delicate predator-prey balances that ecosystems have calibrated over millennia.
"Our work suggests that there's an ecological role that wolves play that won't be played by other animals," he said. "That's probably a role that's worth conserving on landscapes, even outside protected areas. If we're interested in restoring landscapes to a more natural, functioning ecosystem, this would be an important part of that."

Monday, February 13, 2017

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


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

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

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

Wednesday, February 8, 2017

Brown bears reduce wolf kill rates says USU ecologist


Contrary to popular assumptions, researchers on two continents find wolves kill less often in the presence of brown bears
UTAH STATE UNIVERSITY
IMAGE
IMAGE: IN NORTH AMERICA'S YELLOWSTONE NATIONAL PARK, HUNGRY WOLVES WAIT TO ACCESS THEIR ELK KILL AS BROWN BEARS FEAST ON THE SPOILS. UTAH STATE UNIVERSITY ECOLOGIST AIMEE TALLIAN AND COLLEAGUES REPORT... view more 
CREDIT: DANIEL STAHLER, NATIONAL PARK SERVICE
LOGAN, UTAH USA - If you've ever been elbowed out of the way at the dinner table by older, stronger siblings, you'll identify with wolves competing with larger bears for food. A study by Utah State University ecologist Aimee Tallian and colleagues reveals wolves might be at more of a disadvantage than previously thought.
Tallian is lead author of a paper examining competition between wolves and brown bears on two continents published Feb. 8, 2017, in Proceedings of the Royal Society B[DOI: 10.1098/rspb.2016.2368]. 
"Wolves and brown bears coexist across most of their range," says Tallian, who completed a doctoral degree from USU in 2017. "Although competition between predators such as these is widespread in nature, we know little about how brown bears affect wolf predation."
With colleagues in Scandinavia and North America, Tallian examined how brown bears affected wolf kill rates at study sites in northern Europe and Yellowstone National Park.
"We found an unexpected pattern," she says. "Wolves killed less often in the presence of brown bears, which is contrary to the common assumption that wolves kill prey more often to compensate for loss of food to bears."
Tallian says the consistency in results between the systems on different continents suggests brown bear presence actually reduces wolf kill rate, but the researchers aren't sure why.
They surmise wolves, unlike lynx and mountain lion, may not be quickly abandoning their kills, as bears move in take advantage of the spoils.
"The wolves may be hanging around longer, waiting their turn to gain access to food," Tallian says.
She and her colleagues also wonder if wolves kill less frequently because it takes them longer to find prey.
"We think this may be the case, in the spring, when newborn ungulates make easy pickings for bears," Tallian says. "It may simply take more time for wolves to find calves, when there are fewer of them."
Interactions between apex predators can either relax or strengthen their effect on prey and predator populations, she says.
"The team's results suggest that ignoring such interactions may underestimate the effect competition between predators can have on predator populations," Tallian says. "In addition, it's possible to overestimate the impact of multiple predators on prey populations."

Saturday, January 28, 2017

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


A recent wildlife survey led by SERNANP (Servicio Nacional de Áreas Naturales Protegidas por el Estado) and WCS (Wildlife Conservation Society) in the Historic Sanctuary of Machu Picchu in Peru has confirmed that the world-famous site is also home to a biologically important and iconic species: the Andean bear (Tremarctos ornatus).
Funded by the Andean Bear Conservation Alliance, the U.S. Agency for International Development, and the Gordon and Betty Moore Foundation, the year-long survey revealed the presence of Andean bears in more than 95 percent of the 368-square-kilometer study area, which includes the famous Incan ruins of Machu Picchu, one of the most visited places in South America. While it was previously known that Andean bears existed in the sanctuary, the new survey's findings reveal a much wider presence of bears throughout the protected area.
The Historic Sanctuary of Machu Picchu is classified as a World Heritage site by UNESCO (the United Nations Educational, Scientific, and Cultural Organization) and is one of only 35 sites worldwide listed as a mixed natural and cultural site. The findings from this survey are critical for establishing a baseline for future assessments and to plan for the long-term conservation of Andean bears both within and beyond the sanctuary.
"It is amazing that this world famous location is also important habitat for Andean bears," said Dr. Isaac Goldstein, Coordinator of WCS's Andean Bear Program. "The results of the survey will help us to understand the needs of this species and how to manage Andean bears in this location."
With a range stretching from Venezuela to Bolivia, the Andean bear inhabits the mist-shrouded montane forests and upland grasslands of the Andes Mountains and is South America's only native bear species. The Andean bear is sometimes called the spectacled bear due to yellowish or white patches that surround its eyes. The species features prominently in the cultural fabric of the region, yet much is still unknown about the behavior and ecology of the Andean bear.
The survey results also show that the Andean bears of Machu Picchu are not an isolated population, but part of a much larger population connected by montane grasslands that occur over an elevation of 3,400 meters (more than 11,000 feet above sea level). Understanding this connectivity will help wildlife managers to maintain the corridors needed for healthy bear populations. The survey itself is part of a larger effort by SERNANP and its partners to monitor Andean bears across the Machupicchu-Choquequirao Landscape, a large mountainous region containing both archeological sites and natural areas.
Fieldwork to collect data on the presence of Andean bears in the Historic Sanctuary of Machu Picchu was conducted between August 2014 and September 2015. A team of more than 30 trained researchers and park officials looked for signs of bears in a variety of habitats in the Machu Picchu protected area, ranging from Andean rainforest to montane grasslands. The study area was divided into sections 16 square kilometers in size (more than 6 square miles, the typical size of a female Andean bear's range) to evaluate the bear's presence in the protected area. Researchers looked for bear activity such as scat, footprints, and signs of feeding on terrestrial bromeliads (plants native to tropical and subtropical regions) along 166 kilometers (more than 100 miles) of transects throughout the sanctuary.
In addition to finding signs of bears in most of the sanctuary, the research team also determined that the presence of cattle is a potential risk to Andean bears in the sanctuary. The survey results will help inform the effective management of the Historic Sanctuary of Machu Picchu, the most visited protected area in Peru.
WCS has contributed to extensive research on the ecological needs of the Andean bear throughout its range. In 2014, WCS published the document "Andean Bear Priority Conservation Units in Bolivia and Peru" that consolidated information from 25 Andean bear experts on the distribution of the species and recommendations for conservation. In the U.S., WCS's Queens Zoo is home to the only Andean bear exhibit in New York City. Queens Zoo Director and Curator Scott Silver serves as Coordinator for the Andean Bear Species Survival Plan (SSP), a cooperative breeding program administered by the Association of Zoos and Aquariums that ensures genetic variability within accredited zoo populations.

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


Since the year 2000, the Eurasian grey wolf, Canis lupus lupus, has spread across Germany. For Ines Lesniak, doctoral student at the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), and her colleagues, a good reason to have a closer look at the small "occupants" of this returnee and to ask the question whether the number and species of parasites change with an increasing wolf population. This was the case, because the number of parasite species per individual wolf increased as the wolf population expanded. Furthermore, cubs had a higher diversity of parasite species than older animals. The good news: wolf parasites do not pose a threat to human health. The results of this study were published in the scientific online journal "Scientific Reports" of the Nature Publishing Group.
In the course of a long-term study of wolf health in Germany, the internal organs of 53 wolf carcasses were studied in detail. They came from wolves which had died in traffic accidents or were illegally killed between 2007 and 2014.
"Whereas tapeworms are recognisable with the naked eye, the identification of single-celled Sarcocystis parasites was a real challenge, since the species of this genus do not differ morphologically," explains Lesniak.
According to their developmental cycle, endoparasites can be grouped into two types: Some, such as many tapeworms, infect their hosts directly. Others, such as Sarcocystis parasites, first live in an intermediate host, the prey animal of the wolf, and reach their final host, the wolf, only if the intermediate host has been consumed by the final host. With the faeces of the final host, these parasites are released back into the environment. Potential prey animals of the wolf feed then on vegetation that was previously contaminated with the parasites. The parasites thereby invade the intermediate host and settle in the muscle flesh. Roe deer, red deer and wild boar are such intermediate hosts in central Europe. When these are eaten by a wolf, the parasites infect the final host -- the wolf -- and reproduce in its intestines.
By applying sophisticated molecular genetic analyses, the scientists identified 12 Sarcocystis species in the wolf carcasses. They also found four tapeworm species (cestodes), eight roundworm species (nematodes) as well as one fluke species (trematode). In order to examine parasite infections also in the wolf's large prey species, the team collected internal organs of shot prey animals from hunting parties.
In Germany, wolves mainly feed on roe deer, but also red deer and wild boars. Small mammals, such as hares, voles or mice, are very seldom "on the menu." The identified parasites provide indirect evidence for this insight, since fox tapeworms were found in only one of the 53 wolves. Fox tapeworms are transmitted by mice and can occur in all canids, but particularly frequently in foxes. "Good news," Lesniak says, because the larvae of fox tapeworms can cause severe diseases in humans.
The scientists found that the infestation of wolves with parasites varied during their lifetime. "Cubs carry many more parasite species than yearlings or adults." According to Ines Lesniak, such variation in parasite species prevalence can be explained by the more robust immune system of older wolves. Wolves, just like any other wild canid -- other than domestic dogs -- are never dewormed, after all.
Wolves that died at the beginning of the study period had a lower parasite diversity than those who died later. "The bigger the population, the more often wolves are in contact with each other and their prey, and the more often they became infected with different parasites," Lesniak summarises the results.
Currently, there are 46 wolf packs settled within Germany. A pack consists of the parents as well as the cubs of the current and the previous year and can comprise up to ten individuals. "Genetic analyses conducted by our cooperation partners for this study show that the ancestors of the Central European lowland population, which nowadays ranges from Germany to Poland, originated from Lusatia in eastern Germany," Lesniak says. This population was probably initiated by individuals who migrated from the Baltic region at the beginning of the millennium and settled between southern Brandenburg and northern Saxony. From there, they began to spread across northeastern Germany and southwestern Poland, a process which continues to this day.
"Wolves are shy, wild animals. Thus, contact between people and wolves is rare," Lesniak emphasises. "Nevertheless, hunters should boil the leftovers of shot game thoroughly before feeding this to their hunting dogs, in order to avoid possible parasite infections," warns Lesniak. It is also essential to regularly deworm hunting dogs in regions occupied by wolves.
Occasionally, it has been reported that wolves come closer to residential areas; sheep farmers are complaining about losses. "It may well be that today's wolves have learnt that it is easier to find food closer to humans -- those, who once eradicated their wolf forefathers" presumes Lesniak. Of course, it is more convenient for a wolf to break into a sheep enclosure than to chase roe deer in the forest. Therefore, the implementation of appropriate protective measures of domestic animals is very important and now also financially supported by the government in Germany.

Wednesday, January 18, 2017

Tigers could roam again in Central Asia


IMAGE
IMAGE: THIS IS AN ARTIST'S DEPICTION OF A CASPIAN TIGER. view more 
CREDIT: HEPTNER AND SLUDSKIY 1972
Caspian tigers, some of the largest cats that ever lived -- up to 10 feet long and weighing more than 300 pounds -- met a grim end in the middle of the 20th century. 
Until the mid-1960s when they were designated as extinct, they ranged from modern-day Turkey through much of Central Asia, including Iran and Iraq, to northwestern China. The reasons for their extermination are many: poisoning and trapping were promoted by bounties paid in the former Soviet Union until the 1930s; irrigation projects during the Soviet era destroyed the tugay woodlands (a riparian and coastal ecosystem of trees, shrubs and wetlands) and reed thickets that were critical tiger habitat; and the cats' prey disappeared as the riparian habitat vanished. 
But there is a chance that tigers -- using a subspecies that is nearly identical, genetically, to the extinct Caspian -- could be restored to Central Asia.
A study published online in the journal Biological Conservation lays out the options for restoring tigers to Central Asia and identifies a promising site in Kazakhstan that could support a population of nearly 100 tigers within 50 years.
"The territory of the Caspian tiger was vast," said Professor James Gibbs, a member of the research team and a conservation biologist who is director of the Roosevelt Wild Life Station at the College of Environmental Science and Forestry (ESF) in Syracuse, New York. "When they disappeared, the number of nations that hosted tiger populations was reduced by more than half." 
The researchers say introducing tigers in a couple of locations in Kazakhstan won't make a widespread difference immediately but it would be an important first step.
"The idea of tiger reintroduction in Central Asia using the Amur tiger from the Russian Far East as an 'analog' species has been discussed for nearly 10 years. It met with considerable support from the government of Kazakhstan in 2010 during the Global Tiger Forum in St. Petersburg, Russia," said Mikhail Paltsyn, an ESF doctoral candidate who oversaw analytical aspects of the study. 
"But the program needed a strong scientific foundation to evaluate the full habitat potential for tigers and to better explore different possible outcomes of the reintroduction in different scenarios," Paltsyn said. 
In addition to Paltsyn and Gibbs, the research team includes ESF scientists Liza Yegorova, a recent master's graduate; Dr. Igor Chestin, director of WWF-Russia; and Dr. Olga Pereladova, director of WWF Central Asia Program. Paltsyn is a member of the International Union for Conservation of Nature Cat Specialist Group and has served as a consultant with the World Wide Fund for Nature (WWF) and United Nations Development Programme.
The scientists say two factors have combined to raise the possibility of restoring tigers to the Ili-Balkhash region of western Kazakhstan:
    * The breakup of the Soviet Union and introduction of market economies in newly established states has led to the recovery of tiger habitats in some areas as state-sponsored agricultural programs along rivers were abandoned.
    * Recent work in phylogenetics (the study of evolutionary history) indicates Caspian tigers were closely related to Amur tigers that still exist, making Amur tigers a likely "analog" species for restoration of tigers to the region. 
But Paltsyn laid out the challenges that would need to be addressed before tigers start roaming the landscape again. 
"First, it is necessary to stop riparian zone degradation caused by uncontrolled fires. Second, it is vital to restore wild ungulate (broadly defined as a hoofed mammal) populations in the area. That, alone, could take five to 15 years," Paltsyn said. "Third, human safety and socio-economic benefits for local populations need to be addressed to provide a sustainable future for both tigers and people. And, finally, water consumption from the Ili River needs to be regulated in both Kazakhstan and China to support sufficient water level in Balkash Lake for tugay and reed ecosystems - the main tiger habitat. However, WWF and the government of Kazakhstan seem to be ready to deal with all these difficult issues to bring tigers back to Central Asia." 
Tiger reintroduction has support from the Kazakhstan government and local communities because of potential economic benefit from wildlife tourism, small-business growth and employment opportunities at Ili-Balkhash Nature Reserve.
In the study, the researchers analyzed scientific literature that revealed Caspian tigers once lived in an area about 800,000 to 900,000 square kilometers in size (between 300,000 and 350,000 square miles), mostly within isolated patches of riparian ecosystems (land along rivers or streams). Generally, two or three tigers occupied an area that covered about 100 square kilometers (about 40 square miles).
Spatial analyses based on remote sensing data indicated that options for Amur tiger introduction are limited in Central Asia. But at least two habitat patches are potentially suitable for tiger re-establishment, both in Kazakhstan. When the researchers considered current land use and the low density of the local human population, they found the most promising site is the Ili River delta and adjacent southern coast of Balkhash Lake. The river flows from northwestern China into southeastern Kazakhstan; it drains into Balkhash Lake, the 15th largest lake in the world. 
The team identified about 7,000 square kilometers (about 2,700 square miles) of suitable habitat. Population models for animals that tigers typically prey on -- wild boar, Bukhara deer and roe deer -- suggest the area could support a population of between 64 and 98 tigers within 50 years if 40 to 55 tigers are introduced. 
The Amur tiger is apparently the only subspecies that has significantly increased in number in the last 65 years. Scientists estimate some 520 to 540 still live in the wild. Moving some of them from the Russian Far East to the Ili River delta could be enough to eventually establish a wild population in 50 years, and would not harm the Russian population, the study says.
Around the world, similar relocation programs have worked for cat populations. The study says: "... case studies suggest high adaptive potential of big cats to novel environments. We know of no large cat translocation programs that failed strictly due to maladaptation of source population to environment of release."