As settlers pushed westward in the 1800’s many decided to call the mid-west home. The settlers developed thriving agribusiness which had unintended effects on local ecosystems. They depleted the hunting ground the grey wolf relied on to survive. The wolves adapted for survival. Short on options the wolves began to prey on livestock which were easy hunting.
This spurred a century-long genocide against predators including cougars, coyotes, bear, and wolves. For many years, local farmers had permission to hunt wolves indiscriminately. This was a very successful campaign. The last gray wolf pack was killed in Yellowstone National Park in 1926. (1) It would be 50 years (1974) before the grey wolf made it onto the endangered species list and real effort to protect and restore the dwindling population began.
Throughout history we have seen that forcibly adding and removing parts of an ecosystem can have unintended effects. In 1929 environmentalists noticed that foliage in the park wasn’t growing as well. It was dry and not reseeding like it had in the past. Scientists noticed that where trees once grew tall and strong, they were now short and anemic. Food source populations the wolves had kept in check, primarily elk, were exploding in number and began overgrazing the already struggling plant life. (2) In response, park rangers desperate to reduce elk populations issued an unprecedented number of hunting tags. This slowed the deterioration of the park but Yellowstone showed no signs of returning to its previously thriving state. Then there was another unintended effect; the elk population became so low that hunters complained there weren’t enough to hunt. As the park made efforts to bring back the elk population it began to suffer from overgrazing once again. (3) This cycle continued until 1996.
After decades of deliberation between wildlife activists and the local farming community, wolves were reintroduced into the park in 1996. Canada relocated 31 wolves and some smaller packs were also introduced to help diversify the gene pool from local packs. This totaled 76 viable wolves. (4)
No one expected the reintroduction to go as well as it did and for it to have such a fast impact on the park’s ecosystem. Trees grew taller and grasses were not as dry. The elk numbers returned to a manageable rate. Their grazing behavior became less intrusive because they were less bold in their migration patterns. The elk and deer started to reside deeper in the forests rather than in valleys where they were easier prey. Bison, whose numbers were also dwindling, began to rise because there was more foliage to eat. (5) This phenomenon demonstrates a Top-Down Trophic Cascade. This refers to a change to the top predators of the food chain. It describes the ripple effect it has on the entire food chain. There are usually 3 trophic levels in a food chain: predator, herbivore, and primary producer. (6)
When the elk’s behavior changed, it had a remarkable impact on foliage in the park. In only six years, trees were growing 5 times taller than they had in the wolf’s absence. Barren valleys turned into forests where aspen, willow, and cottonwood trees multiplied. This attracted more birds and beavers which enhanced the fish population. Every step of the ecosystem played a part in balancing other plant and wildlife species that had struggled for decades. (6)
The most surprising effect the reintroduction of the gray wolf had was changing the river system in the park. River banks were more stable due to healthy foliage growing in the river beds. This meant that they were eroding the banks much slower. This, in turn, created more pooling areas of the rivers. These provide drinking water and spawning points for fish and water bird life such as ducks, osprey, and pelicans. (6)
The reintroduction of the grey wolf in Yellowstone is a reassuring case study that we at CANA Foundation look to. We understand the catastrophic effect that removing the wild horse from America’s rangelands has had and why it’s critical that we rewild the horse in these areas. We are seeing dried up prairies with dwindling numbers of not only wildlife but insects as well. In the west, there has been a sharp spike in wildfires that is partly attributed to drought and exacerbated by overgrazing of cattle. The prairies are covered in unhealthy plant life that is unable to reseed itself. We need your help to give a voice to the wild horse. It is not too late for us to reverse the destruction that we have inflicted onto our rangelands.
About CANA Foundation
CANA Foundation’s mission is to responsibly restore an ecological balance in our environment through specific rewilding initiatives. These projects support harmony between the humans, plants, and animals that inhabit U.S. rangelands and focus on the restoration of our land’s native habitats through natural resources and indigenous species, like America’s wild horses. CANA initiatives work towards long-term, sustainable solutions that prevent further land degradation, protect and preserve wild horse populations, and encourage a beneficial, thriving ecosystem for today and tomorrow.
Contact CANA Foundation: PO Box 674, Locust Valley, NY 11560 or [email protected]Donate to CANA Foundation
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- U.S. National Park Service (2017, March 21). Wolf Restoration. Retrieved from https://www.nps.gov/yell/learn/nature/wolf-restoration.htm
- Meera Dolasia | DOGOnews (2014, Sept. 18). How the Removal of a ‘Nuisance’ Predator Wreaked Havoc on Yellowstone National Park’s Ecosystem. Retrieved from https://www.dogonews.com/2014/9/18/how-the-removal-of-a-nuisance-predator-wreaked-havoc-on-yellowstone-national-parks-ecosystem
- Lister, B. & McDaniel, C. (2006, April 17). The Wolves of Yellowstone. In Biology: An Interactive Exploration (Ecology 7: Predation). Retrieved from http://www.bioinfo.rpi.edu/bystrc/pub/artWolves.pdf
- Smith, D. W. [Ed] (2016, June). Yellowstone Science, 24(1). Retrieved from https://www.nps.gov/yell/learn/upload/YELLOWSTONE-SCIENCE-24-1-WOLVES.pdf
- Ripple, W. J., & Beschta, R. L. (2012, Jan.). Trophic cascades in Yellowstone: The first 15 years after wolf reintroduction [Abstract]. Biological Conservation, 145(1), 205-213. Retrieved from http://www.sciencedirect.com/science/article/pii/S0006320711004046
- Silliman, B. R. & Angelini, C. (2012). Trophic Cascades Across Diverse Plant Ecosystems. Nature Education Knowledge, 3(10), 44. Retrieved from http://www.nature.com/scitable/knowledge/library/trophic-cascades-across-diverse-plant-ecosystems-80060347
- Featured Image: Yellowstone National Park [Flickr] (2016, April 6). Alpa female, Canyon pack. Retrieved from https://www.flickr.com/photos/yellowstonenps/27301720962
- Figure 1: Smith, D. W., Stahler, D. R., Metz, M. C., Cassidy, K. A., Stahler, E. E., Almberg, E. S., & McIntyre, R. (2016, June). Wolf Restoration in Yellowstone: Reintroduction to Recovery. Yellowstone Science, 24(1), 5-11. Retrieved from https://www.nps.gov/yell/learn/ys-24-1-wolf-restoration-in-yellowstone-reintroduction-to-recovery.htm