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Wolf Article 1right131635500Although wolf packs once roamed from the Arctic tundra to Mexico, loss of habitat and extermination programs led to their demise throughout most of the United States by early in the 1900s. In 1973, the US Fish and Wildlife Service listed the northern Rocky Mountain wolf (Canis lupus) as an endangered species and designated Greater Yellowstone as one of three recovery areas. From 1995 to 1997, 41 wild wolves from Canada and northwest Montana were released in Yellowstone National Park. As expected, wolves from the growing population dispersed to establish territories outside the park where they are less protected from human-caused mortalities. The park helps ensure the species’ long-term viability in Greater Yellowstone and has provided a place for research on how wolves may affect many aspects of the ecosystem.Wolves (back) are larger than coyotes (middle) and red foxes (front). Wolves are highly social animals and live in packs. Worldwide, pack size will depend on the size and abundance of prey. In Yellowstone, average pack size is 10 individuals. The pack is a complex social family, with older members (often the alpha male and alpha female) and subordinates, each having individual personality traits and roles within the pack. Packs defend their territory from other, invading packs by howling and scent marking with urine.Wolves consume a wide variety of prey, large and small. They efficiently hunt large prey that other predators cannot usually kill. In Yellowstone, 90% of their winter prey is elk; 10–15% of their summer prey is deer. They also kill bison. Many other animals benefit from wolf kills. For example, when wolves kill an elk, ravens arrive almost immediately. Coyotes arrive soon after, waiting nearby until the wolves are sated. Bears will attempt to chase the wolves away, and are usually successful. Many other animals—from magpies to invertebrates—consume the remains.From 1995 to 2000, in early winter, elk calves comprised 50% of wolf prey and bull elk comprised 25%. That ratio reversed from 2001 to 2007, indicating changes in prey vulnerability and availability. The discovery of this change emphasizes the importance of long-term monitoring to understand predator-prey dynamics. Changes in wolf predation patterns and impacts on prey species like elk are inextricably linked to other factors such as other predators, management of ungulates outside the park, and weather (e.g. drought, winter severity). Weather patterns influence forage quality and availability, ultimately impacting elk nutritional condition. Consequently, changes in prey selection and kill rates through time result from complex interactions among these factors. Current NPS research focusses on the relative factors driving wolf predation over the last two decades.An estimated 528 wolves resided in the Greater Yellowstone Ecosystem as of 2015.As of December 2016, there were at least 108 wolves in the park. Eleven packs were noted.In general, wolf numbers have fluctuated between 83 and 108 wolves from 2009 to 2016.They inhabit most of the park, peak activity is at dawn and dusk.The northern range of Yellowstone is one of the best places in the world to watch wolves.26–36 inches tall at the shoulder, 4–6 feet long from nose to tail tip.Males weigh 100–130 pounds, females weigh 80–110 pounds.Home range within the park is 185–310 square miles (300– 500 km2); varies with pack size, food availability, and season.Average lifespan in the park is 4–5 years. Average lifespan outside is 2–3 years. The oldest known wolf to live here was 12.5 years.Two main color variations exist in Yellowstone in approximately equal proportions: black and gray.Prey primarily on hoofed animals. In Yellowstone, 90% of winter diet is elk; summer prey consist of more deer and smaller mammals.Mate in February.Give birth to average of five pups in April after a gestation period of 63 days.Young emerge from den at 10–14 days; pack remains at the den for 3–10 weeks unless disturbed.Leading cause of death for wolves within the park is death by other wolves.Leading cause of death for wolves outside the park is human-caused.?Wolves kill each other and other carnivores, such as coyotes and cougars, usually because of territory disputes or competition for carcasses. In 2000, however, the subordinate female wolves of the Druid pack exhibited behavior never seen before: they killed their pack’s alpha female; then they carried her pups to a central den and raised them with their own litters.The Northern Range is the hub of wildlife in Yellowstone National Park. Occupying just 10 percent of the park, it is winter range for the biggest elk herd in Yellowstone and is arguably the most carnivore-rich area in North America. Early management of predators caused dynamic changes to the ecosystem. The reappearance of carnivores on the landscape has had significant and sometimes unexpected impacts on the resident grazers and their habitat.?In the first years following wolf restoration, the population grew rapidly as the newly formed packs spread out to establish territories with sufficient prey. The wolves have expanded their population and range, and now are found throughout the Greater Yellowstone Ecosystem.Disease periodically kills a number of pups and old adults. Outbreaks of canine distemper have occurred in 2005, 2008 and 2009. In 2005, distemper killed two-thirds of the pups within the park. Infectious canine hepatitis, canine parvovirus, and bordetella have also have been confirmed among Yellowstone wolves, but their effect on mortality is unknown.Sarcoptic mange, an infection caused by the mite (Sarcoptes scabiei), reached epidemic proportions among wolves on the northern range in 2009. The mite is primarily transmitted through direct contact and burrows into the wolf’s skin. This process can initiate an extreme allergic reaction and cause the wolf to scratch the infected areas, which often results in hair loss and secondary infections. By the end of 2011, the epidemic had mostly subsided; however, the infection is still currently present at lower prevalences throughout the park.Wolf packs are highly territorial and communicate with neighboring packs by scent-marking and howl- ing. Occasionally packs encounter each other and these interactions are typically aggressive. Larger packs often defeat smaller groups, unless the small group has more old adult or adult male members. Sixty-five percent of collared wolves are ultimately killed by rival packs. The park’s wolf population has declined substantially since 2007, when the count was 171. Most of the decrease has been in packs on the northern range, where it has been attributed primarily to the decline in the elk population and available territory. Canine distemper and sarcoptic mange have also been factors in the population decline.Each year, park researchers capture a small proportion of wolves and fit them with radio tracking collars. These collars enable researchers to gather data on an individual, and also monitor the population as a whole to see how wolves are affecting other animals and plants within the park. Typically, at the end of each year, only 20% of the population is collared. Wolves in the Northern Rocky Mountains have met the US Fish and Wildlife Service’s criteria for a recovered wolf population since 2002. As of December 2015, the US Fish & Wildlife Service estimated about 1,704 wolves and 95 breeding pairs in the Northern Rocky Mountain Distinct Population Segment. The gray wolf was removed from the endangered species list in 2011 in Idaho and Montana but is currently protected as endangered species in the state of Wyoming. Wolves are hunted in Idaho and Montana under state hunting regulations.Videos: Wolf Article 2Wolves are causing a trophic cascade of ecological change, including helping to increase beaver populations and bring back aspen, and vegetation. On a quiet spring morning, a resounding "Slap!" reverberates through the air above a remote stream leading to Lake Yellowstone. Over much of the past century, it has been a rarely heard noise in the soundscape that is Yellowstone National Park, but today is growing more common-the sound of a beaver slapping its tail on the water as a warning to other beavers.When the grey wolf was reintroduced into the Greater Yellowstone Ecosystem in 1995, there was only one beaver colony in the park, said Doug Smith, a wildlife biologist in charge of the Yellowstone Wolf Project. Today, the park is home to nine beaver colonies, with the promise of more to come, as the reintroduction of wolves continues to astonish biologists with a ripple of direct and indirect consequences throughout the ecosystem.A flourishing beaver population is just one of those consequences, said Smith. What happened, said Smith, is that the presence of wolves triggered a still-unfolding cascade effect among animals and plants-one that will take decades of research to understand. "It is like kicking a pebble down a mountain slope where conditions were just right that a falling pebble could trigger an avalanche of change," Smith mused. So how did this avalanche of change work out for the beaver? To answer that, you have to go back to the 1930s, when the wolf was killed off in Yellowstone. Even though Yellowstone elk were still preyed upon by black and grizzly bears, cougars and, to a lesser extent, coyotes, the absence of wolves took a huge amount of predatory pressure off the elk, said Smith. As a result, elk populations did very well-perhaps too well. Two things happened: the elk pushed the limits of Yellowstone's carrying capacity, and they didn't move around much in the winter-browsing heavily on young willow, aspen and cottonwood plants. That was tough for beaver, who need willows to survive in winter.This created a counterintuitive situation. Back in 1968, said Smith, when the elk population was about a third what it is today, the willow stands along streams were in bad shape. Today, with three times as many elk, willow stands are robust. Why? Because the predatory pressure from wolves keeps elk on the move, so they don't have time to intensely browse the willow.Indeed, a research project headed by the U.S. Geological Survey in Fort Collins found that the combination of intense elk browsing on willows and simulated beaver cuttings produced stunted willow stands. Conversely, simulated beaver cutting without elk browsing produced verdant, healthy stands of willow. In the three-year experiment, willow stem biomass was 10 times greater on unbrowsed plants than on browsed plants. Unbrowsed plants recovered 84 percent of their pre-cut biomass after only two growing seasons, whereas browsed plants recovered only 6 percent. With elk on the move during the winter, willow stands recovered from intense browsing, and beaver rediscovered an abundant food source that hadn't been there earlier.As the beavers spread and built new dams and ponds, the cascade effect continued, said Smith. Beaver dams have multiple effects on stream hydrology. They even out the seasonal pulses of runoff; store water for recharging the water table; and provide cold, shaded water for fish, while the now robust willow stands provide habitat for songbirds."What we're finding is that ecosystems are incredibly complex," he said. In addition to wolves changing the feeding habits of elk, the rebound of the beaver in Yellowstone may also have been affected by the 1988 Yellowstone fires, the ongoing drought, warmer and drier winters and other factors yet to be discovered, Smith said.Biologists are often faced with the grim task of documenting the cascade effects of what happens when a species is removed from an ecosystem, by local extirpation or even extinction. In Yellowstone, biologists have the rare, almost unique, opportunity to document what happens when an ecosystem becomes whole again, what happens when a key species is added back into the ecosystem equation."In the entire scientific literature, there are only five or six comparable circumstances," Smith said. "What we're seeing now is a feeding frenzy of scientific research." Scott Creel, an ecology professor at Montana State University, is hip-deep in that feeding frenzy. "My research has been in the Gallatin Canyon," said Creel, where elk inhabit four drainages. Wolves come and go, he said, enabling him to study what elk do in the presence and absence of wolves. "Elk have proven to be pretty adaptable," Creel said. "When wolves are around, they're more vigilant and do less foraging."Elk move into heavy timber when wolves are around, Creel added, but return to the grassy, open meadows when wolves go away. Creel and other researchers are still working out what that means in terms of the elk's diet and whether there are costs associated with this behavior.Rather surprisingly, elk herd size breaks up into smaller units when wolves are around, said Creel, who had expected herd size to get bigger as a defense mechanism. "I think they're trying to avoid encounters with wolves," he said, by being more vigilant, moving into the timber and gathering in smaller herd units.Researchers have also determined that wolves, in the recent absence of hard winters, are now the primary reason for elk mortality. Before wolf reintroduction, deep snows were the main determinant of whether an elk was going to die.Researchers from the University of California at Berkeley determined that the combination of less snow and more wolves has benefited scavengers both big and small, from ravens to grizzly bears. Instead of a boom and bust cycle of elk carrion availability-as existed before wolves and when winters were harder-there's now a more equitable distribution of carrion throughout winter and early spring, said Chris Wilmers in the on-line journal Public Library of Science Biology. He added that scavengers that once relied on winter-killed elk for food now depend on wolf-killed elk. That benefits ravens, eagles, magpies, coyotes and bears (grizzly and black), especially as the bears emerge hungry from hibernation."I call it food for the masses," said Ed Bangs, wolf recovery coordinator for the U.S. Fish and Wildlife Service. He said he was genuinely surprised by the vast web of life that is linked to wolf kills. "Beetles, wolverine, lynx and more," he said. "It turns out that the Indian legends of ravens following wolves are true-they do follow them because wolves mean food."Wolf Article 3CORVALLIS, Ore. - The reintroduction of wolves into Yellowstone National Park may be the key to maintaining groves of cottonwood trees that were well on their way to localized extinction, and is working to rebalance a stream ecosystem in the park for the first time in seven decades, Oregon State University scientists say in two new studies. The data show a clear and remarkable linkage between the presence of wolves and the health of an entire streamside ecosystem, including two species of cottonwoods and the myriad of roles they play in erosion control, stream health, and nurturing diverse plant and animal life. The findings of these studies were recently published in Ecological Applications, a journal of the Ecological Society of America, and the journal Forest Ecology and Management. "In one portion of the elk's winter range along the Lamar River of Yellowstone National Park, we found that there were thousands of small cottonwood seedlings," said Robert Beschta, professor emeritus in the College of Forestry at OSU and an expert on streams and riparian systems. "There should also have been hundreds of young trees, but there were none. Long-term elk browsing had been preventing any seedlings from getting taller." That pattern was common throughout the study area - lots of seedlings in combination with large cottonwood trees generally more than 70 years old, but little or nothing in between. Young cottonwoods, willows, and other streamside woody species are a preferred food for browsing elk during the harsh winters in northern Yellowstone, when much of the other forage is buried under snow. But when packs of wolves historically roamed the area, food was not the only consideration for elk, which had to be very careful and apparently avoided browsing in high-risk areas with low visibility or escape barriers. Wolves were systematically killed in the Yellowstone region and many other areas of the West beginning in the late 1800s. A concentrated effort between 1914 and 1926 finished the job - the last known wolf pack disappeared in 1926. "I considered a variety of potential reasons that might explain the historical decline of cottonwoods that began in the 1920s and have continued up to the last couple of years," said Beschta. "I looked at climate change, lack of floods, fire suppression, natural stand dynamics, and numbers of elk. But none of those factors really explained the problem. "Ultimately, it became clear that wolves were the answer." While elk populations fluctuated over the decades when wolves were absent, browsing behavior appears to represent an important factor related to streamside impacts. With no fear of wolves, the elk could graze anywhere they liked and for decades have been able to kill, by browsing, nearly all the young cottonwoods. Other streamside species such as willows and berry-producing shrubs also suffered. That in turn began to play havoc with an entire streamside ecosystem and associated wildlife, including birds, insects, fish and others. Trees and shrubs were lost that could have helped control stream erosion. Food webs broke down. "Before the wolves came back, it was pretty clear that in some areas we were heading towards an outright extinction of cottonwoods," Beschta said. Now, with the recent reintroduction of wolves back into Yellowstone in 1995, streamside shrubs and cottonwoods within the Lamar Valley are beginning to become more prevalent and taller, and were the focus of a second study in the same area. That study outlines how the fear of attack by wolves apparently prevents browsing elk from eating young cottonwood and willows in some streamside zones. With the renewed presence of wolves, young cottonwoods and willows have been growing taller each year over the last four years on "high-risk" sites, where elk apparently feel vulnerable due to terrain or other conditions that might prevent escape. In contrast, on "low-risk" sites, they are still being browsed by elk and show little increase in height. "In one case where a gully formed an escape barrier for elk, the tree height went up proportionally as the gully deepened and formed an increasing barrier to escape," said William Ripple, a professor with the College of Forestry at OSU. "Where the fear factor of wolves is high, the young trees and willows are doing much better and growing taller." Traditionally, "keystone" predators such as wolves were known to influence the population of other animals that they preyed on directly, such as elk or antelope. What researchers are now coming to better understand is the "trophic effect," or cascade of changes that can take place in an ecosystem when an important part is removed, Ripple said. The comparatively pristine conditions of a national park allowed this type of research to make "cause and effect" studies more feasible, the scientists point out. "The removal of wolves for 70 years - and then their return - actually set the stage for a scientific experiment with fairly compelling results," Beschta said. In a larger context, the studies also raise valid questions about other complex and poorly understood interactions between plants, animals, and wildlife in disturbed ecosystems across much of the American West, and perhaps elsewhere in the world, the scientists say. In some areas of the West, the disappearance of up to 90 percent of the aspen trees has been documented - another species of plant that is also highly vulnerable to animal browsing when it is young. "The last period when aspen trees in Yellowstone escaped the effects of elk browsing to generate trees into the forest overstory was the 1920s," Ripple said, "which is also when wolves were removed from the park." But in at least one place - America's first national park - there is now cause for hope. While it is too early to confirm the widespread recovery of cottonwoods and willows, the reintroduction of wolves appears to have put a stop to major declines in the survival of these plants, the researchers found. "One point that should not be missed is this is actually great news for the potential recovery of cottonwood trees and mature willows in Yellowstone National Park," Ripple said. "We now have a pretty good idea why they were in decline and the return of wolves should help pave the way for their recovery. "Even though it may take a very long time, for a change it looks like we're headed in the right direction."Wolf Article 4Everyone’s heard the story that bringing back wolves to the Yellowstone ecosystem suddenly returned it to normal, but did you know that claim may be only partially true? To see both sides of the story, let’s look at one of the most successful wolf reintroduction programs in history, at Yellowstone National Park. Wolves were officially declared extinct in the park by 1926. This set off a chain of ecological events known as a trophic cascade – when one tiny change in an ecosystem ripples out and causes many other effects. After the wolves were gone, the bears and coyotes that were left weren’t able to kill as many elk as the wolves had done. Soon, the elk population skyrocketed, and they devastated the ecosystem by eating too much young, tender willow and aspen trees. Once those trees were gone, a whole host of other animals left: birds, beaver, and fish that lived in the beaver ponds. The beaver dams broke and allowed water to flow through too fast to soak up in the surrounding landscape. The land converted to grasslands and dry shrub-lands. Compared to its former glory, it was now a barren wasteland.After the successful reintroduction of the wolves, beginning in 1995, it seemed like the landscape changed and did a complete 180 from where it had been heading. More wolves meant less elk, and the elk that survived spent less time eating because they were keeping an eye out for wolves. The surviving trees weren’t being eaten as much, so they started to grow taller and to spread. As the trees grew taller, birds returned to nest in them. Finally, the beaver came back as well, and started building dams that drew fish and even more water and trees back to the area. It seemed like just the simple act of adding in one key species—wolves—allowed the system to return to normal. This is the story that became popular in the years right after the wolf release. Unfortunately, things aren’t often what they appear to be, and the Yellowstone wolf reintroduction story is no exception.Ecology is a field of science that studies relationships among all the different things in an environment. In the case of the wolf reintroduction, it’s impossible to say with total certainty that the wolves were the only reason that the Yellowstone ecosystem recovered. And even more surprising, it seems like parts of Yellowstone may have even not recovered at all!There are countless other factors that could have acted together to cause the response seen in Yellowstone. Yellowstone has been in and out of big drought cycles for years, wreaking havoc with both the plants and the animals that eat them. Bear predation on elk has also increased in recent years, meaning that the wolves alone aren’t causing the elk decline. These are only a couple of many explanations that could have affected elk numbers and the subsequent recovery. Additionally, some areas of the park seem to have not recovered at all and still look like a pre-wolf ecosystem, with dry former wetlands, fast-flowing creeks, and low biodiversity. Scientists were trying to wrap their head around why these areas weren’t responding, and they decided to create an experiment to test some different explanations.The experiment had three scenarios: first, they had a control stream to measure willow growth as it was already occurring. Second, they had an elk exclosure to keep elk from eating willows along a stream. Finally, they had an elk exclosure and made some simulated beaver dams. The results were startling: keeping elk out of an area alone had no effect on willow growth. You needed a combination of less elk and more water from beaver dams to bring the ecosystem back to normal. Without both, it wouldn’t work. Many people believe that the wolf reintroduction didn’t do anything to restore the Yellowstone ecosystem; others believe that the wolf was the sole factor causing the recovery. The truth, as with most things, probably lies somewhere in the middle: wolves were responsible for some, but not all, of the ecosystem response seen in Yellowstone.It might seem like scientists are just nit-picking details at this point, but as Arthur Middleton, a former Yellowstone ecologist pointed out in a New York Times article, “We now know that elk are tougher, and Yellowstone more complex, than we gave them credit for. By retelling the same old story about Yellowstone wolves, we distract attention from bigger problems, mislead ourselves about the true challenges of managing ecosystems, and add to the mythology surrounding wolves at the expense of scientific understanding.” ................
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