Yellowstone National Park is home to one-half the world’s hydrothermal features, vibrant landscapes, mountain wildernesses, and according to a park brochure titled, “Wildlife,” it has “the largest concentration of mammals in the United States.” Yet, that wasn’t always the case. Before 1995, the park had one big problem-a vital predator had vanished. This absence for over 70 years resulted in extraordinary damage to the trees, the animals, and even the waterways. Something had to change, and scientists wondered if returning that predator to the park could be the answer. This is the story of why and how the reintroduction of wolves into Yellowstone saved the park by creating dramatic changes in the ecosystem for animals, plants, and rivers. However, it is important to first understand why there were no wolves in Yellowstone.
In the beginning, wolves were a major predator in America. According to conservationist and nature author, Judy Lehmberg, in her CBS article, “Nature Up Close; The Best Wolf Ever”, there were over “400,000 gray wolves” called the United States home when the Europeans first arrived. Yet, “but by 1930 that number was very close to zero, including in Yellowstone.” When the Yellowstone National Park Protection Act of 1872 was enacted, it offered some protection for the animals, plants, and rivers to keep the park’s “natural condition” (National Park Service). That natural condition included wolves. However, as history has shown, wolves were hunted, trapped, and shot. The decreasing number of wolves in the last 250 years proves that there was no protection for wolves. In fact, most people thought, “. . . fewer wolves meant more deer, elk and moose” (Lehman). While hunting wolves was allowed, the government’s approval was in the form of a bounty on wolves in 1914. The United States considered all wolves to be, “destructive to agriculture” (Dixon). Wolves didn’t have a chance. They continued to decline year after year until almost no wolves were left in the United States. As for Yellowstone, the last two wolves were shot in 1926. It wasn’t until 1973 that wolves took their place on the newly adopted Endangered Species Act, but the damage to the park’s ecosystem was already clear and a change was needed if the natural beauty of the park was to be saved. Something had to change.
Nevertheless, knowing something is wrong and discovering exactly what it is are two different things. Mara Dolph, a conservationist biologist, in her article, “What Happens When the Top Predator Is Removed From an Ecosystem?” explains that, “Ecosystems are complex and diverse, with many levels and intricate relationships between organisms. Removing any level from an ecosystem disrupts a delicate balance that may have evolved over millions of years”. Park rangers and scientists observations in Yellowstone noticed that the number of foxes, badgers, beavers, songbirds, and moose were decreasing each year, which told them that the system of checks and balances in Yellowstone’s ecosystem didn’t add up. The damage was evident as explained in a video created by Everything Science:
The deer and elk populations increased substantially resulting in over grazing particularly of the Willows and other vegetarian important to soil and riverbank structure leading to heavy erosion as a top predator wolves were one of Yellowstone's linchpins holding together the delicate balance between predator and prey the removal in the early 20th century disrupted food webs and set up something called a trophic cascade the Wolves natural predators in this case the elk multiplied all while consuming increasing amounts of foliage this hurt the species that relied on that vegetation like the birds who nested in the trees and the beavers who use the Willows to create their dams and without the beaver dams hundreds of native fish species started to decline and as the fish declined so did the animals that fed on them like the foxes and bears but removing a single species a cascade of negative effects propagated outward throughout the ecosystem (“How the Wolves Saved Yellowstone” 00:59-01:47).
However, even though there were other predators in Yellowstone, wolves were the major predator of elk, so “. . . 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” according to Brodie Farquhar in his article, “Wolf Reintroduction Changes Ecosystem”. The deer and elk herds overgrazed the willow and aspen stands. The trees produced new sprouts, but “. . . most of these sprouts were consumed by elk, preventing recruitment of new saplings and trees” (Smith-Douglas 213). The decrease in trees meant a decrease in songbirds who nest and feed in the trees. It also affected the beaver populations who “. . . rely on tall, abundant willow stands for dam-building material and winter food caches” (Smith-Douglas 212) The absence of beavers “led to a number of hydrologic changes, including widening. . . of stream channels and a drop in the floodplain water table” (Smith-Douglas 213) Scientists determined, the only way to stop the damage was to bring back the top elk predator and reintroduce wolves to save the park.
Consequently, wolves, not just any wolves, were reintroduced. “Biologists decided that the best wolves were ones that knew how to hunt Yellowstone prey . . . Thus, we have Canadian wolves in Yellowstone” (Halfpenny 11). When they were released, the wolves did what they were supposed to do and started hunting elk. “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” (Farquhar). The beavers built new dams and the rivers began to recover. The video by Sustainable Human, “How Wolves Changed the Rivers,” described the dramatic effect when wolves started moving the elk as “The wolves changed the behavior of the rivers. They began to meander less, there was less erosion, the channels narrowed” (03:13-03:17). The absence of wolves damaged the park, but their reintroduction helped repair the damage.
In conclusion, the removal of wolves in the Yellowstone ecosystem caused severe problems when there was no predator to move the elk and lower the numbers in their herds. However, the reintroduction of wolves into Yellowstone saved the park by creating dramatic changes in the ecosystem for animals, plants, and rivers. The lesson learned is best stated by Katharine Lackey, “. . . most ecologists say removing predators today would be a mistake. The way ecosystems put themselves back together after such a problem is still something scientists are trying to understand. The lesson is let’s not let things get as bad as they did with 70 years without wolves.”
Works Cited:
Dolph, Mara. “What Happens When the Top Predator Is Removed From an Ecosystem?” Education, Seattle PI, 21 Nov. 2017, education.seattlepi.com/happens-top-predator-removed-ecosystem-3496.html.
Farquhar, Brodie. “Wolf Reintroduction Changes Ecosystem.” My Yellowstone Park, My Yellowstone Park, 30 June 2020, www.yellowstonepark.com/things-to-do/wolf-reintroduction-changes-ecosystem.
“Gray Wolf.” National Parks Service, U.S. Department of the Interior, www.nps.gov/yell/learn/nature/wolves.htm.
“How Wolves Change Rivers - YouTube.” Sustainable Human.org, 13 Feb. 2014, www.youtube.com/watch?v=oSBL7Gk_9QU.
Lackey, Katharine. “Yellowstone's Wolves Are Back, but They Haven't Restored the Park's Ecosystem. Here's Why.” USA Today, Gannett Satellite Information Network, 2018,www.usatoday.com/story/tech/science/2018/09/07/wolves-reintroduction-yellowstone-ecosystem/.
Lehmberg, Judy. “Nature up Close: The Best Wolf Ever.” CBS News, CBS Interactive, 21 Oct. 2018, www.cbsnews.com/news/nature-up-close-the-best-wolf-ever-yellowstone-national-park/.
Smith, Douglas W., and Gary Ferguson. Decade of the Wolf: Returning the Wild to Yellowstone, Lyons Press, 2012, pp. 212, 213, 215).
“Wildlife.” Yellowstone Wildlife, Yellowstone Media, 1999, www.yellowstonenationalpark.com/wildlife.htm.
“Yellowstone National Park Protection Act (1872).” National Parks Service, U.S. Department of the Interior, www.nps.gov/yell/learn/management/yellowstoneprotectionact1872.htm#:~:text=The%20United%20States%20Congress%20established,Park%20Protection%20Act%20into%20law.&text=AN%20ACT%20to%20set%20apart,River%20as%20a%20public%20park.
In the beginning, wolves were a major predator in America. According to conservationist and nature author, Judy Lehmberg, in her CBS article, “Nature Up Close; The Best Wolf Ever”, there were over “400,000 gray wolves” called the United States home when the Europeans first arrived. Yet, “but by 1930 that number was very close to zero, including in Yellowstone.” When the Yellowstone National Park Protection Act of 1872 was enacted, it offered some protection for the animals, plants, and rivers to keep the park’s “natural condition” (National Park Service). That natural condition included wolves. However, as history has shown, wolves were hunted, trapped, and shot. The decreasing number of wolves in the last 250 years proves that there was no protection for wolves. In fact, most people thought, “. . . fewer wolves meant more deer, elk and moose” (Lehman). While hunting wolves was allowed, the government’s approval was in the form of a bounty on wolves in 1914. The United States considered all wolves to be, “destructive to agriculture” (Dixon). Wolves didn’t have a chance. They continued to decline year after year until almost no wolves were left in the United States. As for Yellowstone, the last two wolves were shot in 1926. It wasn’t until 1973 that wolves took their place on the newly adopted Endangered Species Act, but the damage to the park’s ecosystem was already clear and a change was needed if the natural beauty of the park was to be saved. Something had to change.
Nevertheless, knowing something is wrong and discovering exactly what it is are two different things. Mara Dolph, a conservationist biologist, in her article, “What Happens When the Top Predator Is Removed From an Ecosystem?” explains that, “Ecosystems are complex and diverse, with many levels and intricate relationships between organisms. Removing any level from an ecosystem disrupts a delicate balance that may have evolved over millions of years”. Park rangers and scientists observations in Yellowstone noticed that the number of foxes, badgers, beavers, songbirds, and moose were decreasing each year, which told them that the system of checks and balances in Yellowstone’s ecosystem didn’t add up. The damage was evident as explained in a video created by Everything Science:
The deer and elk populations increased substantially resulting in over grazing particularly of the Willows and other vegetarian important to soil and riverbank structure leading to heavy erosion as a top predator wolves were one of Yellowstone's linchpins holding together the delicate balance between predator and prey the removal in the early 20th century disrupted food webs and set up something called a trophic cascade the Wolves natural predators in this case the elk multiplied all while consuming increasing amounts of foliage this hurt the species that relied on that vegetation like the birds who nested in the trees and the beavers who use the Willows to create their dams and without the beaver dams hundreds of native fish species started to decline and as the fish declined so did the animals that fed on them like the foxes and bears but removing a single species a cascade of negative effects propagated outward throughout the ecosystem (“How the Wolves Saved Yellowstone” 00:59-01:47).
However, even though there were other predators in Yellowstone, wolves were the major predator of elk, so “. . . 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” according to Brodie Farquhar in his article, “Wolf Reintroduction Changes Ecosystem”. The deer and elk herds overgrazed the willow and aspen stands. The trees produced new sprouts, but “. . . most of these sprouts were consumed by elk, preventing recruitment of new saplings and trees” (Smith-Douglas 213). The decrease in trees meant a decrease in songbirds who nest and feed in the trees. It also affected the beaver populations who “. . . rely on tall, abundant willow stands for dam-building material and winter food caches” (Smith-Douglas 212) The absence of beavers “led to a number of hydrologic changes, including widening. . . of stream channels and a drop in the floodplain water table” (Smith-Douglas 213) Scientists determined, the only way to stop the damage was to bring back the top elk predator and reintroduce wolves to save the park.
Consequently, wolves, not just any wolves, were reintroduced. “Biologists decided that the best wolves were ones that knew how to hunt Yellowstone prey . . . Thus, we have Canadian wolves in Yellowstone” (Halfpenny 11). When they were released, the wolves did what they were supposed to do and started hunting elk. “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” (Farquhar). The beavers built new dams and the rivers began to recover. The video by Sustainable Human, “How Wolves Changed the Rivers,” described the dramatic effect when wolves started moving the elk as “The wolves changed the behavior of the rivers. They began to meander less, there was less erosion, the channels narrowed” (03:13-03:17). The absence of wolves damaged the park, but their reintroduction helped repair the damage.
In conclusion, the removal of wolves in the Yellowstone ecosystem caused severe problems when there was no predator to move the elk and lower the numbers in their herds. However, the reintroduction of wolves into Yellowstone saved the park by creating dramatic changes in the ecosystem for animals, plants, and rivers. The lesson learned is best stated by Katharine Lackey, “. . . most ecologists say removing predators today would be a mistake. The way ecosystems put themselves back together after such a problem is still something scientists are trying to understand. The lesson is let’s not let things get as bad as they did with 70 years without wolves.”
Works Cited:
Dolph, Mara. “What Happens When the Top Predator Is Removed From an Ecosystem?” Education, Seattle PI, 21 Nov. 2017, education.seattlepi.com/happens-top-predator-removed-ecosystem-3496.html.
Farquhar, Brodie. “Wolf Reintroduction Changes Ecosystem.” My Yellowstone Park, My Yellowstone Park, 30 June 2020, www.yellowstonepark.com/things-to-do/wolf-reintroduction-changes-ecosystem.
“Gray Wolf.” National Parks Service, U.S. Department of the Interior, www.nps.gov/yell/learn/nature/wolves.htm.
“How Wolves Change Rivers - YouTube.” Sustainable Human.org, 13 Feb. 2014, www.youtube.com/watch?v=oSBL7Gk_9QU.
Lackey, Katharine. “Yellowstone's Wolves Are Back, but They Haven't Restored the Park's Ecosystem. Here's Why.” USA Today, Gannett Satellite Information Network, 2018,www.usatoday.com/story/tech/science/2018/09/07/wolves-reintroduction-yellowstone-ecosystem/.
Lehmberg, Judy. “Nature up Close: The Best Wolf Ever.” CBS News, CBS Interactive, 21 Oct. 2018, www.cbsnews.com/news/nature-up-close-the-best-wolf-ever-yellowstone-national-park/.
Smith, Douglas W., and Gary Ferguson. Decade of the Wolf: Returning the Wild to Yellowstone, Lyons Press, 2012, pp. 212, 213, 215).
“Wildlife.” Yellowstone Wildlife, Yellowstone Media, 1999, www.yellowstonenationalpark.com/wildlife.htm.
“Yellowstone National Park Protection Act (1872).” National Parks Service, U.S. Department of the Interior, www.nps.gov/yell/learn/management/yellowstoneprotectionact1872.htm#:~:text=The%20United%20States%20Congress%20established,Park%20Protection%20Act%20into%20law.&text=AN%20ACT%20to%20set%20apart,River%20as%20a%20public%20park.
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