Yellowstone Wolf Reintroduction

Hayden Garfield

Blog Post

            In1995 the National Park and U.S. Fish and Wildlife services reintroduced 14 wolves back into Yellowstone National Park. In 1996, 17 more wolves were brought into the park and released. This was the first time that wolves (Canis lupus) had roamed Yellowstone since the early 1900s. Due to people’s views of wolves as pests, they had been hunted and trapped to extinction in the Greater Yellowstone Ecosystem. In this blog post I wish to discuss the importance of the reintroduction of wolves and how it has influenced the ecology in the Greater Yellowstone Ecosystem.

            Shortly after wolves were exterminated from Yellowstone in the early 1900s, the elk population in Yellowstone began to increase exponentially. Numbers rose rapidly until the population had risen to over 20,000 elk on the northern range. This obviously had its effects on the rest of the environment. With that many elk, grazing resources needed to be provided. The elk began to eat willow and aspen saplings thus stunting the growth of the willow and aspen population. Without the reproduction of these trees and bushes they began to disappear from the park. With them, many animals began to disappear as well such as beavers in the 1950s, and variety of birds that relied on willows and aspen trees for their livelihood. Evidence of this was provided by William J. Ripple, a professor of botany at Oregon State University. When looking at old photographs of the park he noticed the abundance of willow and aspen trees and compared that with what he saw in the park in the 1990s. He sampled 98 aspen trees and found that only two of these trees had begun their growth after the 1920s, right around the same time the wolves were exterminated. He also observed that these two trees were in locations that elk had previously been hesitant to go in fear of being killed by wolves. He concluded that the absence of wolves was in fact a major factor in the decline of willow and aspen trees. As stated above, this decline is far reaching and is having a major effect not only on plant life, but also on the other animal life in the park.

            When wolves were reintroduced into the park in 1995 and 1996, the elk numbers dropped dramatically. In less than a decade, the numbers had dropped by half, leaving about 10,000 elk in the Greater Yellowstone Ecosystem thus stabilizing the number of elk in the northern herd. This drop in the number of elk has obviously had its effect on the ecosystem. But it is not only the drop in the number of elk, but also the change in the behavior of the elk that is being observed that has made a noticeable difference in the Park. With the threat of wolves again present in Yellowstone, elk have changed their feeding patterns. Instead of feeding down in the river bottoms where many willow and aspen saplings attempt to grow, the elk have begun to feed in locations where they have great visibility and can see if a predator is approaching. This has allowed for these saplings to take root and grow to a height where they can survive and reproduce instead of being eaten by elk in their early stages of life. With the return of a willow population the first beaver dams in over 50 years are being observed in the Lamar Valley in Yellowstone. With the return of the beaver comes dams which can slow the flow of water thus reducing erosion to the banks of the Lamar River and Slough Creek. With this slower running water also comes better habitat for the trout, otters, and other waterfowl population.

            Other changes that have occurred since the reintroduction of wolves has included the number of coyotes in the ecosystem. Coyote numbers have dropped by more than 50% because of the reintroduction of wolves. At first this seems like a negative, but when one takes a closer look at it, it is evident that this is in fact a positive. With a decrease in coyotes there is an increase in their prey such as voles, rabbits, foxes, etc. many of which were struggling in the absence of wolves. Wolves are also masterful at hunting elk and will, at times, take down multiple elk a week. When they have received their fill of the meat, they leave the remaining food to be scavenged on by bears, coyotes, foxes, and many species of birds.

            It is clear that wolves have had a significant impact on the Greater Yellowstone Ecosystem in helping to balance out the environment. Of course, there are those who still do not believe that wolves do not have a positive impact on the environment or that they have made too much of a difference, but for me there is so much scientific evidence that can back up the positive influence of wolves on a healthy ecosystem. It is also important that we as a society understand that we should not remove parts of the ecosystem that are meant to be there because it will throw off the balance of the ecosystem. We need to be aware of our surroundings and that everything has its own function.

The reason that I chose to post on this topic was because I absolutely love Yellowstone and the wildlife that lives there. I have gone there every year since I was a very young child with my family. Although wolves were introduced the same year that I was born I have been able to observe many of the effects that wolves have had on the ecosystem that I discussed in this paper such as the decrease in the number of elk and the increase in willow and aspen tree growth. My father is a science teacher and has taught me about many of the topics discussed in this post as well from the time I was young. I feel like I have a vested interest on this topic because of the amount of time I have spent in Yellowstone and on the subject of Yellowstone, especially the wildlife there.  

https://www.nature.com/scientificamerican/journal/v290/n6/pdf/scientificamerican0604-76.pdf